ALBERT

Description: Since 1991, induced earthquakes have been observed and linked to gas production in the Groningen field. Recorded waveforms are complex, resulting partly from a Zechstein salt layer overlying the reservoir and partly from free‐surface reverberations, internal multiples, interface conversions, guided waves, and waves diving below the reservoir. Therefore, picking of polarities or amplitudes for use in moment tensor inversion is problematic, whereas phase identification may be circumvented employing full waveform techniques. Although moment tensors have become a basic tool to analyze earthquake sources, their uncertainties are rarely reported. We introduce a method for probabilistic moment tensor estimation and demonstrate its use on the basis of a single event within the Groningen field, concentrating on detailed tests of input data and inversion parameters to derive rules of good practice for moment tensor estimation of events recorded in the Groningen field. In addition to the moment tensor, event locations are provided. Hypocenters estimated simultaneously with moment tensors are often less sensitive to uncertainties in crustal structure, which is pertinent for the application to the Groningen field, because the task of relating earthquakes to specific faults hitherto suffers from a limited resolution of earthquake locations. Because of the probabilistic approach, parameter trade‐offs, uncertainties, and ambiguities are mapped. In addition, the implemented bootstrap method implicitly accounts for modeling errors affecting every station and phase differently. A local 1D velocity model extracted from a full 3D velocity model yields more consistent results than other models applied previously. For all velocity models and combinations of input data tested, a shift in location of 1 km to the south is observed for the test event compared to the public catalog. A full moment tensor computed employing the local 1D velocity model features negative isotropic components and may be interpreted as normal fault and collapse at reservoir level.

Description: The Mushgai-Khudag complex is part of the Late Mesozoic Central Asian carbonatite province. Fluorite mineralization is manifested throughout the province, including the Mushgai-Khudag complex. We have investigated the geochemical features and fluid inclusions of fluorites from different types of fluorite-bearing rocks. Fluorite from quartz-fluorite rocks has rare earth element (REE) concentrations in the range of 10500-144300 ppm and the highest light REE contents, with (La/Yb)N = 56-960. Fluorite from the fluorite-apatite-celestine rocks has slightly lower REE enrichment, especially light REE content, with concentrations of 200-5900 ppm and (La/Yb)N = 18-204. Fluorite from the fluorite-calcite rocks is characterized by REE contents of 22-1100 ppm and a variable (La/Yb)N of 0.6-59. These variations in the fluorite REE composition from different types of rocks were probably caused by the fact that at elevated temperatures, fluorine-containing light REE complexes are more stable than fluorine-containing heavy REE complexes. The progressive enrichment of medium and heavy REEs in the latter fluorite is related to fluid evolution. The homogenization temperature and salinity values of fluid inclusions in the Mushgai-Khudag fluorites vary between 550 and 185 °C and from rather high to 2 wt.%, respectively. The parental fluids of the fluorite-bearing rocks evolved from quartz-fluorite rocks to fluorite-apatite-celestine rocks to fluorite-calcite rocks. The key component was changed from sulfate to carbonate-chloride along with the high to medium temperature decrease (∼500-245 °C).

Description: The Mushgai-Khudag alkaline‑carbonatite complex, located in southern Mongolia within the Central Asian Orogenic Belt (CAOB), comprises a broad range of volcanic and subvolcanic alkaline silicate rocks (melanephelinite-trachyte and shonkinite-alkaline syenite, respectively). Magnetite-apatite rocks, carbonatites, and fluorite mineralization are also manifested in this area. The complex formed between 145 and 133 Ma and is contemporaneous with late Mesozoic alkaline–carbonatite magmatism within the CAOB. Major and trace element characteristics of silicate rocks in the Mushgai-Khudag complex imply that these rocks were formed by the fractional crystallization of alkaline ultramafic parental magma. Magnetite-apatite rocks may be a product of silicate-Ca-Fe-P liquid immiscibility that took place during the alkaline syenite crystallization stage. The Mushgai-Khudag rocks have variable and moderately radiogenic Sr(87Sr/86Sr(i) = 0.70532–0.70614), Nd(t) = −1.23 to 1.25) isotopic compositions. LILE/HFSE values and Sr-Nd isotope compositions indicate that the parental melts of Mushgai-Khudag were derived from a lithospheric mantle source that was affected by a metasomatic agent in the form a mixture of subducted oceanic crust and its sedimentary components. The 18OSMOW and 18CPDB values for calcites in carbonatites range from 16.8‰ to 19.2‰ and from −3.9‰ to 2.0‰, respectively. C-O covariations in calcites of the Mushgai-Khudag carbonatites can be explained by the slight host limestone assimilation.

Description: The Dead Sea Transform (DST) was formed in the Mid-Cenozoic, about 18 Myr ago, as a result of the breakaway of the Arabian plate from the African plate. Higher resolution information about the sub-Moho structure is still sparse in this region. Here we study seismic discontinuities in the mantle lithosphere in the region of the DST using a modified version of the P- and S-receiver function method. We use open data from permanent and temporary seismic stations. The results are displayed in a number of depth profiles through the study area. The Moho is observed on both sides of the transform at nearly 40 km depth by S-to-p and in P-to-s converted signals. The lithosphere-asthenosphere boundary (LAB) on the eastern side of the DST is observed near 180–200 km depth, which is according to our knowledge the first LAB observation at that depth in this region. This observation could lead to the conclusion that the thickness of the Arabian lithosphere east of the DST is likely cratonic. In addition, we observe in the entire area a negative velocity gradient (NVG) at 60–80 km depth, which was previously interpreted as LAB.

Description: Climate change makes it necessary to re-evaluate the erosion potential of forest infrastructure. We used the Forest Service WEPP interfaces (FS WEPP) to compare soil erosion potentials of two competing logging practices in steep terrain in the Northern Black Forest, Germany: (1) Felling with harvesters and logging with forwarders in slope line with optional traction supporting winches. (2) Felling by chainsaw, logging with a cable winch, and further transport of logs via forest dirt roads. After forest harvest we measured erosion, runoff, and DOC concentration in runoff from 50 m sections of two machine tracks, two cable tracks, and a dirt road for 2 years. The erosion measurements were used to validate FS WEPP management options and a regionally adjusted CLIGEN input file. With these parameterizations we compared the erosion potential of the two practices on subcatchment scale by modeling return periods and total sediment export with FS WEPP. Model results show that logging operations with heavy machinery in slope line are less prone to soil erosion than logging operations including winch logging and additional dirt roads. The former produces less sediment in its worst-case configuration than the latter in its most moderate configuration by a factor of two. Model results also show that erosion prevention benefits from long periods of 10 years between two harvests.

Description: Drilling, coring, and geophysical logging were performed with the MARUM-MeBo200 seafloor drilling rig to investigate gas hydrate occurrences of the Danube deep sea fan, off Romania, Black Sea. Three sites within a channel-levee complex were investigated. Geophysical log data of P-wave velocity, electrical resistivity, and spectral gamma ray are combined with core-derived physical properties of porosity, magnetic susceptibility, and bulk density. Core- and log physical property data are used to define a time-depth conversion by synthetic seismogram modeling, which is then used to interpret the seismic data. Individual polarity reversed reflectors within the stratigraphic column drilled are linked to reduction in P-wave velocity and bulk density. Those reflectors (and associated reflection packages) are accompanied by distinct and systematic changes in sediment porosity, magnetic susceptibility, and electrical resistivity. Overall, the sediments at drill site GeoB22605 (MeBo-17) represent the younger (upper) levee sequence of the channel, that has been eroded at drill site GeoB22603 (MeBo-16). Splicing seismic data across the channel from the East (MeBo-16) to the West (MeBo-17) demonstrates the continuation of reflectors underneath the channel. The upper ~50 m below seafloor (mbsf) at site MeBo-16 do not stratigraphically belong to the same sequence of the (deeper) levee-deposits. Above the marked erosional unconformity, sediments at Site MeBo-16 are likely derived by a mixture of repeated slump-events (identified as seismically transparent units) interbedded with hemi-pelagic sedimentation. Similarly, sediments within the upper ~20 mbsf at Site MeBo-17 are not stratigraphically the same levee-deposits, but are derived by a mixture of slump-events (also seen in the marked seafloor amphitheatre architecture of a large failure complex extending further upslope) and hemi-pelagic sedimentation. All observations combined show that the seismically observed stratigraphic pattern represents a reflectivity sequence mostly driven by variations in density (porosity) and correspondingly by changes in P-wave velocity and electrical resistivity. Observations from the geophysical log- and core, as well as geochemical data, show no evidence for the presence of any significant gas hydrates within the drilled/cored sequences.

Description: These short, informal newsletters, issued every month on approximately the first day of the month, are intended to keep IUGG Member National Committees informed about the activities of the IUGG Associations and actions of the IUGG Secretariat. Special issues are sometimes distributed mid-month as deemed appropriate. The content usually includes a synopsis of scientific meetings during the following three months in order to illustrate the disciplinary and geographical diversity of IUGG interests. E-Journals may be forwarded to those who will benefit from the information.

Description: A seismic network was installed in Helsinki, Finland to monitor the response to an ∼6‐kilometer‐deep geothermal stimulation experiment in 2018. We present initial results of multiple induced earthquake seismogram and ambient wavefield analyses. The used data are from parts of the borehole network deployed by the operating St1 Deep Heat Company, from surface broadband sensors and 100 geophones installed by the Institute of Seismology, University of Helsinki, and from Finnish National Seismic Network stations. Records collected in the urban environment contain many signals associated with anthropogenic activity. This results in time‐ and frequency‐dependent variations of the signal‐to‐noise ratio of earthquake records from a 260‐meter‐deep borehole sensor compared to the combined signals of 24 collocated surface array sensors. Manual relocations of ∼500 events indicate three distinct zones of induced earthquake activity that are consistent with the three clusters of seismicity identified by the company. The fault‐plane solutions of 14 selected ML 0.6–1.8 events indicate a dominant reverse‐faulting style, and the associated SH radiation patterns appear to control the first‐order features of the macroseismic report distribution. Beamforming of earthquake data from six arrays suggests heterogeneous medium properties, in particular between the injection site and two arrays to the west and southwest. Ambient‐noise cross‐correlation functions reconstruct regional surface‐wave propagation and path‐dependent body‐wave propagation. A 1D inversion of the weakly dispersive surface waves reveals average shear‐wave velocities around 3.3km/s below 20 m depth. Consistent features observed in relative velocity change time series and in temporal variations of a proxy for wavefield partitioning likely reflect the medium response to the stimulation. The resolution properties of the obtained data can inform future monitoring strategies and network designs around natural laboratories.

Description: In recent years, urban and rural flash floods in Europe and abroad have gained considerable attention because of their sudden occurrence, severe material damages and even danger to life of inhabitants. This contribution addresses questions about possibly changing environmental conditions which might have altered the occurrence frequencies of such events and their consequences. We analyze the following major fields of environmental changes. Altered high intensity rain storm conditions, as a consequence of regional warming; Possibly altered runoff generation conditions in response to high intensity rainfall events; Possibly altered runoff concentration conditions in response to the usage and management of the landscape, such as agricultural, forest practices or rural roads; Effects of engineering measures in the catchment, such as retention basins, check dams, culverts, or river and geomorphological engineering measures. We take the flash-flood in Braunsbach, SW-Germany, as an example, where a particularly concise flash flood event occurred at the end of May 2016. This extreme cascading natural event led to immense damage in this particular village. The event is retrospectively analyzed with regard to meteorology, hydrology, geomorphology and damage to obtain a quantitative assessment of the processes and their development. The results show that it was a very rare rainfall event with extreme intensities, which in combination with catchment properties and altered environmental conditions led to extreme runoff, extreme debris flow and immense damages. Due to the complex and interacting processes, no single flood cause can be identified, since only the interplay of those led to such an event. We have shown that environmental changes are important, but—at least for this case study—even natural weather and hydrologic conditions would still have resulted in an extreme flash flood event.

Description: Low Earth Orbit (LEO) enhanced Global Navigation Satellite System (LeGNSS) has been recognized as the promising positioning system in the near future where mega-constellations of LEO satellites are used for precise positioning. Fast Precise Point Positioning (PPP) convergence can be achieved if LEO constellations are employed into current GNSS due to the fast motion of LEO satellites. In order to fulfill this purpose, it is of great importance to design a LEO constellation or to conduct LEO constellation optimization for global precise positioning. In this article, several aspects of LEO constellations in terms of number of LEO orbital planes, number of LEO satellites, and the selection of orbital inclinations are statistically analyzed to find out the suitable LEO constellation for LeGNSS. It is shown that the combination of several LEO constellations with different inclinations together as a whole would be much more appropriate to get a more uniform distribution of the number of visible LEO satellites along the latitude for global fast convergent PPP. With a total 240 LEO satellites of orbital inclinations at 90°, 60°, and 35° selected in this article, one minute convergence time for PPP is achieved on a global scale.

Description: Diffusive transport and sorption processes of uranium in the Swiss Opalinus Clay were investigated as a function of partial pressure of carbon dioxide , varying mineralogy in the facies and associated changes in porewater composition. Simulations were conducted in one-dimensional diffusion models on the 100 m-scale for a time of one million years using a bottom-up approach based on mechanistic surface complexation models as well as cation exchange to quantify sorption. Speciation calculations have shown, uranium is mainly present as U(VI) and must therefore be considered as mobile for in-situ conditions. Uranium migrated up to 26 m in both, the sandy and the carbonate-rich facies, whereas in the shaly facies 16 m was the maximum. The main species was the anionic complex . Hence, anion exclusion was taken into account and further reduced the migration distances by 30 %. The concentrations of calcium and carbonates reflected by the set determine speciation and activity of uranium and consequently the sorption behaviour. Our simulation results allow for the first time to prioritize on the far-field scale the governing parameters for diffusion and sorption of uranium and hence outline the sensitivity of the system. Sorption processes are controlled in descending priority by the carbonate and calcium concentrations, pH, pe and the clay mineral content. Therefore, the variation in porewater composition resulting from the heterogeneity of the facies in the Opalinus Clay formation needs to be considered in the assessment of uranium migration in the far field of a potential repository.

Description: The International Geodynamics and Earth Tide Service (IGETS) was established in 2015 by the International Association of Geodesy (IAG). IGETS continues the activities of the Global Geodynamics Project (GGP, 1997-2015) to provide support to geodetic and geophysical research activities using superconducting gravimeter (SG) data within the context of an international network. The Walferdange Underground Laboratory for Geodynamics (WULG) is located at the middle of a long labyrinth of galleries which originally have been established for the commercial extraction of gypsum. Exceptional temperature and humidity stability, the absence of water and human perturbations, distance from the ocean and easy access, were some of the motivations for initially choosing this site for instrumentation and Earth tide research. Instruments to measure the micro deformations produced by the tidal forces have been developed and tested in the Laboratory for more than 30 years. Ground deformations and earthquakes are or have been recorded continuously by means of spring gravimeters, vertical and horizontal pendulums, long base water tube tiltmeters, vertical and horizontal strain meters, short period and broad band seismometers. Meteorological parameters (temperature, humidity and atmospheric pressure), as well as radon gas emissions, are also continuously monitored in various locations within the mine. In 2000, the Minister of Research of the Grand-Duchy of Luxembourg decided to establish a new International Reference Station for Intercomparisons of Absolute Gravimeters (ISIAG). The instrumentation to support the project includes a superconducting gravimeter OSG-CT040, an absolute gravimeter FG5X-216, and other ancillary equipment necessary to support research. In January 2002, a first superconducting gravimeter was installed. The instrument was then stopped in March 2003 due to an abnormally large instrumental drift. In December 2003, it was replaced by a brand-new gravimeter with the same name and which continuously operates since that date. Absolute gravity measurements have been performed on a regular time base to calibrate the superconducting gravimeter and to estimate its instrumental drift. Since 2003, the WULG hosted three European Comparisons and one International Comparison of Absolute Gravimeters. It was the first international comparison outside the walls of the BIPM (Bureau International des Poids et Mesures) in Sèvres (France) where it had traditionally been organized for 30 years.

Description: The Global Positioning System (GPS) permanent stations at the equatorial and southern sub-tropical hydrobelts of South America undergo the highest seasonality on the Earth due to hydrological loadings. Fortunately, there are products that account for such variations, although some of them have not been properly evaluated. For instance, global solutions of Gravity Recovery and Climate Experiment (GRACE) are band-limited to lower frequencies; therefore, comparisons with GPS data must account for such spectral inconsistencies. It is proposed to spatially average 39 GPS sites by applying Gaussian smoothing, which allows comparisons with long-wavelength part of GRACE solutions by Center for Space Research (CSR), GeoForschungszentrum, and Jet Propulsion Laboratory. Comparisons are also carried out with loadings from Noah-driven Global Land Data Assimilation System (GLDAS) and GRACE mass concentration (mascon) solution by Goddard Space Flight Center. Results show that CSR best reduces the variances of the radial displacements considering both spatially filtered (70%) and unfiltered (53%) GPS data covering the period from Jan 2010 to Dec 2015. However, GLDAS-Noah underestimates the amplitudes of vertical loadings, which might be due to unmodeled inland water and groundwater storages. While acknowledging that a denser distribution of GPS stations is needed, the findings still shed light on the quality of the global hydrological loading products based on GRACE and GLDAS datasets, which might be of interest to the respective science teams.

Description: This project started in October 2015 with a crazy idea : prepare and submit a funding application for an international, multidisciplinary and non-traditional scientific outreach project… within the next 48 hours. Well, it worked out. A group of highly motivated young researchers from Canada and Europe united to combine arts and science and produce a series of outreach comic strips about permafrost (frozen ground). The aim of the project is to present and explain scientific research conducted across the circumpolar Arctic, placing emphasis on field work and the rapidly changing northern environment. The target audience is kids, youth, parents and teachers, with the general goal of making permafrost science more fun and accessible to the public. Because guess what : permafrost represents an area of more than twenty million km2 in the Northern Hemisphere, a huge area. As the climate warms, permafrost thaws and becomes unstable for houses, roads and airports. This rapid thawing of previously frozen ground also disrupts plant and animal habitats, impacts water quality and the ecology of lakes, and releases carbon into the atmosphere as greenhouse gases, making climate change even stronger. Hence permafrost and its response to climate change concerns us all. The project received initial support from the International Permafrost Association (IPA) as a targeted ‘Action Group’, and since then several other sponsors have joined the project. Here we are, now, two years after this first idea. What you are about to read is the result of an iterative process of exchanging ideas between artists and scientists. We first made an application call and received 49 applications from artists in 16 countries. Through a formal review process, we then selected two artists to work on this project: Noémie Ross from Canada, and Heta Nääs from Finland. With input from scientists, Noémie and Heta created fantastic cartoons that explain some of the changes happening to the environment in permafrost areas, how they affect people and wildlife, and what scientists are doing to better understand these changes to help people find innovative ways to adapt. We wish everyone plenty of fun reading this booklet and we would like to thank all those who supported this project.

Description: Suliniut una oktobari 2015-imi isumassarsiamit ingasattumit aallartippoq : nunat tamalaat akornanni, suliat assigiinngitsut tunngavigalugit nalinginnaanngitsumillu ilisimatusarnermi ujartuilluni suliniummut aningaasaliiffigineqarnissamut qinnuteqaasiorit nassiullugulu… akunnerit 48-t tulliuttut iluani. Tassa, iluatsippoq. Inuusuttualuit ilisimatusartut piumassusilerujussuit Canadameersut Europameersullu suleqatigiillutik eqqumiitsuliorneq ilisimatusarnerlu ataatsimoorlutik ataqatigiissippaat titartakkanillu arlalinnik nunamut qeriuaannartumut tunngasunik suliaqarlutik. Suliniummi anguniarneqarpoq Issittumi ilisimatuussutsikkut ilisimatusarnerup ingerlanneqartup saqqummiunnissaa nassuiaannissaalu, tassani pingaartinneqarpoq asimi suliaqarneq avatangiisillu allanngoriartupiloornerat. Atuartorineqarusuttut tassaapput meeqqat, inuusuit, angajoqqaat ilinniartitsisullu, nuna qeriuaannartoq pillugu ilisimatusarnerup nuannersumik tamanullu paasiuminartunngortinnissaa anguniarlugu. Tassami imaakkami : nuna qeriuaannartoq nunarsuup avannarpasissortaani 20 mio. km2-isut annertutigivoq, nunarujussuaq. Silallu kissakkiartornerani, nuna qeriuaannartoq aakkiartulerpoq illut, aqquserngit mittarfiillu qajannarsipput. Siornatigut nunap qerisimasup aakkiartupiloornerata kinguneranik naasut uumasullu uumaffii akornusersorneqartarput, erngup pitsaassusia tatsinilu uumassusillit sunnerneqartarput aamma silaannarmut CO2 gassit silaannarmik kissakkiartortitsisartut aniatinneqartarput, silap pissusiata allanngoriartorneranut annertusaataasumik. Taamaattumik nuna qeriuaannartoq aamma silap pissusiata allanngoriartorneranut qanoq qisuariarnersoq tamatta ilisimasariaqarparput. Suliniutip aallartisarnerani International Permafrost Association tapersiisuuvoq, kingornalu aningaasaliisut allat aamma ilanngupput. Tassunga killippugut, maannakkut, isumassarsisoqareerneranit ukiut marluk qaangiuttut. Maanna atuarnialikkat tassaavoq eqqumiitsuliortut ilisimatuullu isumassarsiaminnik paarlaasseqatigiittarnerisa kingunerat. Aallaqqaammut qinnuteqaqqusigatta eqqumiitsuliortunit qinnuteqaatit 49-t nunanit 16-init tigusimavavut. Nalilersuilluariarluta eqqumiitsuliortut marluk suliniummi uani sulisussatut qinerpavut : Noémie Ross Canada-meersoq, aamma Heta Nääs Finland-imeersoq Ilisimatuunit immersorneqarlutik Noémie aamma Heta alutornarluinnartunik titartaapput, taakkulu nunani qeriuaannartuni avatangiisit qisuariarnerisa ilaannik nassuiaapput, qanoq taakku inunnut uumasunullu sunniuteqarnersut, qanorlu ilisimatuut allannguutit taakku paasilluarniarlugit iliuuseqarnersut, taama inuit nutaaliaasumik naleqqussarnissaannut ikiorniarlugit. Tamassi kissaappassi mappersagannguaq atuarussiuk nuannisarumaartusi, suliniummullu tapersersuisut tamaasa qutsavigaagut.

Description: Dette projekt startede med en vild idé i oktober 2015 : Skriv en ansøgning om finansiering af et internationalt, tværfagligt og utraditionelt videnskabeligt outreach-projekt... inden for de næste 48 timer. Og det virkede. En gruppe stærkt motiverede unge forskere fra Canada og Europa gik sammen for at kombinere kunst og videnskab og lave en række tegneserier om permafrost (frossen jord). Formålet med projektet er at præsentere og forklare videnskabelig forskning, udført på tværs af det arktiske område, med vægt på feltarbejde og det arktiske miljø i hurtig forandring. Målgruppen er børn, unge, forældre og lærere, og det overordnede mål er at gøre videnskab om permafrost sjovere og mere tilgængelig for offentligheden. For tænk engang : permafrost repræsenterer et område på mere end tyve millioner km2 på den nordlige halvkugle, et enormt område. Eftersom klimaet bliver varmere, tør permafrosten og bliver et ustabilt underlag for huse, veje og lufthavne. Denne hurtige optøning af den tidligere frosne jord, ændrer også planters og dyrs habitater, påvirker vandkvaliteten og søernes økologi samt frigiver kulstof til atmosfæren som drivhusgasser, hvilket gør klimaforandringerne endnu stærkere. Derfor vedrører permafrost og dens reaktion på klimaforandringer os alle. Projektet modtog fra starten støtte fra ”International Permafrost Association” (IPA) som en målrettet ‘Action Group’, og siden da er flere andre sponsorer kommet med i projektet. Her er vi nu to år efter denne første ide. Det, du nu skal til at læse, er resultatet af en udveksling af ideer mellem kunstnere og forskere. Vi opfordrede kunstnere til at deltage og modtog 49 ansøgninger fra kunstnere i 16 lande. Ud af alle ansøgerne valgte vi to kunstnere til projektet : Noémie Ross fra Canada og Heta Nääs fra Finland. Med input fra forskere, skabte Noémie og Heta fantastiske tegneserier, der forklarer nogle af de ændringer, der sker i miljøet i permafrostområder, hvordan de påvirker mennesker og dyreliv, og hvad forskere gør for bedre at forstå disse ændringer for at hjælpe folk med at finde innovative måder at tilpasse sig på. Vi ønsker alle masser af sjov med dette hæfte, og vi vil gerne takke alle dem, der støttede projektet.

Description: This project started in October 2015 with a crazy idea : prepare and submit a funding application for an international, multidisciplinary and non-traditional scientific outreach project… within the next 48 hours. Well, it worked out. A group of highly motivated young researchers from Canada and Europe united to combine arts and science and produce a series of outreach comic strips about permafrost (frozen ground). The aim of the project is to present and explain scientific research conducted across the circumpolar Arctic, placing emphasis on field work and the rapidly changing northern environment. The target audience is kids, youth, parents and teachers, with the general goal of making permafrost science more fun and accessible to the public. Because guess what : permafrost represents an area of more than twenty million km2 in the Northern Hemisphere, a huge area. As the climate warms, permafrost thaws and becomes unstable for houses, roads and airports. This rapid thawing of previously frozen ground also disrupts plant and animal habitats, impacts water quality and the ecology of lakes, and releases carbon into the atmosphere as greenhouse gases, making climate change even stronger. Hence permafrost and its response to climate change concerns us all. The project received initial support from the International Permafrost Association (IPA) as a targeted ‘Action Group’, and since then several other sponsors have joined the project. Here we are, now, two years after this first idea. What you are about to read is the result of an iterative process of exchanging ideas between artists and scientists. We first made an application call and received 49 applications from artists in 16 countries. Through a formal review process, we then selected two artists to work on this project: Noémie Ross from Canada, and Heta Nääs from Finland. With input from scientists, Noémie and Heta created fantastic cartoons that explain some of the changes happening to the environment in permafrost areas, how they affect people and wildlife, and what scientists are doing to better understand these changes to help people find innovative ways to adapt. We wish everyone plenty of fun reading this booklet and we would like to thank all those who supported this project.

Description: Dette projekt startede med en vild idé i oktober 2015 : Skriv en ansøgning om finansiering af et internationalt, tværfagligt og utraditionelt videnskabeligt outreach-projekt... inden for de næste 48 timer. Og det virkede. En gruppe stærkt motiverede unge forskere fra Canada og Europa gik sammen for at kombinere kunst og videnskab og lave en række tegneserier om permafrost (frossen jord). Formålet med projektet er at præsentere og forklare videnskabelig forskning, udført på tværs af det arktiske område, med vægt på feltarbejde og det arktiske miljø i hurtig forandring. Målgruppen er børn, unge, forældre og lærere, og det overordnede mål er at gøre videnskab om permafrost sjovere og mere tilgængelig for offentligheden. For tænk engang : permafrost repræsenterer et område på mere end tyve millioner km2 på den nordlige halvkugle, et enormt område. Eftersom klimaet bliver varmere, tør permafrosten og bliver et ustabilt underlag for huse, veje og lufthavne. Denne hurtige optøning af den tidligere frosne jord, ændrer også planters og dyrs habitater, påvirker vandkvaliteten og søernes økologi samt frigiver kulstof til atmosfæren som drivhusgasser, hvilket gør klimaforandringerne endnu stærkere. Derfor vedrører permafrost og dens reaktion på klimaforandringer os alle. Projektet modtog fra starten støtte fra ”International Permafrost Association” (IPA) som en målrettet ‘Action Group’, og siden da er flere andre sponsorer kommet med i projektet. Her er vi nu to år efter denne første ide. Det, du nu skal til at læse, er resultatet af en udveksling af ideer mellem kunstnere og forskere. Vi opfordrede kunstnere til at deltage og modtog 49 ansøgninger fra kunstnere i 16 lande. Ud af alle ansøgerne valgte vi to kunstnere til projektet : Noémie Ross fra Canada og Heta Nääs fra Finland. Med input fra forskere, skabte Noémie og Heta fantastiske tegneserier, der forklarer nogle af de ændringer, der sker i miljøet i permafrostområder, hvordan de påvirker mennesker og dyreliv, og hvad forskere gør for bedre at forstå disse ændringer for at hjælpe folk med at finde innovative måder at tilpasse sig på. Vi ønsker alle masser af sjov med dette hæfte, og vi vil gerne takke alle dem, der støttede projektet.

Description: This project started in October 2015 with a crazy idea : prepare and submit a funding application for an international, multidisciplinary and non-traditional scientific outreach project… within the next 48 hours. Well, it worked out. A group of highly motivated young researchers from Canada and Europe united to combine arts and science and produce a series of outreach comic strips about permafrost (frozen ground). The aim of the project is to present and explain scientific research conducted across the circumpolar Arctic, placing emphasis on field work and the rapidly changing northern environment. The target audience is kids, youth, parents and teachers, with the general goal of making permafrost science more fun and accessible to the public. Because guess what : permafrost represents an area of more than twenty million km2 in the Northern Hemisphere, a huge area. As the climate warms, permafrost thaws and becomes unstable for houses, roads and airports. This rapid thawing of previously frozen ground also disrupts plant and animal habitats, impacts water quality and the ecology of lakes, and releases carbon into the atmosphere as greenhouse gases, making climate change even stronger. Hence permafrost and its response to climate change concerns us all. The project received initial support from the International Permafrost Association (IPA) as a targeted ‘Action Group’, and since then several other sponsors have joined the project. Here we are, now, two years after this first idea. What you are about to read is the result of an iterative process of exchanging ideas between artists and scientists. We first made an application call and received 49 applications from artists in 16 countries. Through a formal review process, we then selected two artists to work on this project: Noémie Ross from Canada, and Heta Nääs from Finland. With input from scientists, Noémie and Heta created fantastic cartoons that explain some of the changes happening to the environment in permafrost areas, how they affect people and wildlife, and what scientists are doing to better understand these changes to help people find innovative ways to adapt. We wish everyone plenty of fun reading this booklet and we would like to thank all those who supported this project.

Description: Ground motion models (GMM) have been employed in several domains, from traditional seismic hazard and risk analysis to more recent shakemaps and rapid loss assessment. In this framework, eGSIM is a Python package and web application intended to help engineers and seismologist in understanding how different models compare for specific earthquake scenarios and how well they fit to observed ground motion data, producing results as visual plot or tabular data in standard, accessible and convenient formats (CSV, HDF, JSON and several image formats). Based on OpenQuake, a popular open-source Python library for seismic hazard and risk analysis, eGSIM incorporates and makes available in two user-friendly interfaces hundreds of published GMMs implemented and tested in OpenQuake: an online graphical user interface (GUI) accessible at https://egsim.gfz-potsdam.de, ideal for comparisons that can be visualized or downloaded as images, and a web application programming interface (web API), implemented along the lines of popular seismological web services (FDSN), more suited for comparisons that may be automatized in scheduled jobs, or need to be integrated into custom code and further processed in the user's own workflows. By incorporating databases in form of so-called flatfiles (ESM) and regionalizations derived from seismic hazard models (SHARE, ESHM20), eGSIM allows users to seamlessly select data for comparison and models for comparison based on regions of interest. It also features management scripts to smoothly incorporate new flatfiles or regionalizations from future research projects.Moreover, via the generation of flatfile templates based on a custom selection of GMMs, and the possibility to upload user-defined flatfiles, eGSIM facilitates the non-trivial task of compiling data for model comparison, and can be used to analyze ground motions from any data set recorded anywhere in the world, including rapid analysis of earthquake records following large events.

Description: Disaster Risk Reduction (DRR), Disaster Risk Management (DRM), and Climate Change Adaptation (CCA) involve a variety of stakeholders with different backgrounds, organizational frameworks, divergent concerns, and sometimes competing agendas. This requires forums where such groups can meet in order to enhance understanding, reconcile different views, and potentially assist each other in meeting their respective goals. One means of establishing such an exchange involves serious games. During the ESPREssO (Enhancing Synergies for disaster Prevention in the European Union) project, three such games, referred to as RAMSETE (Risk Assessment Model Simulation for Emergency Training Exercise), were developed. They were based on table-top, role-playing, scenario-based exercises, and their purpose was for stakeholder information elicitation about policy issues related to DRR, DRM, and CCA. Participants in the exercises were assigned roles where they interacted and negotiated in order to deal with the presented scenarios. The scenarios were primarily concerned with selecting an optimal set of policies to deal best with the issue in question. The games, while sometimes including an operational element, were meant to examine the motivations behind the decisions made, rather than to test or to train in response protocols. The participants in general found the games to be useful for framing discussions about complex issues, while their problem-solving character was appreciated and enjoyed. Such games allow stakeholders to openly discuss and challenge ideas, policies, and processes in a manner they would not normally do in their daily activities, with other professionals who they would not necessarily be in frequent contact with.

Description: The ESPREssO Project set out to propose ways to inform more coherent national and European approaches on Disaster Risk Reduction (DRR) and Climate Change Adaptation (CCA). A critical step in this process is the identification of existing barriers to effective collaboration, finding new areas of common ground, and ways to enhance co-operation with regards to CCA and DRR policymaking in Europe. This is particularly important considering the potential relationships between CCA and DRR activities at the regional, national, European and global levels. Serious games have emerged as a valuable tool to communicate information and catalyse discussion in many policy arenas. The games have the power to inform, mainly by exposing strengths and weaknesses of a system but not necessarily create policy choices. This paper presents the development process and rationale behind creation of RAMSETE I, a serious game developed by and for the ESPREssO Project to elicit information from its stakeholders in aiming to inform synergies between CCA and DRR sectors. The results assess its application as a device to frame discussions during an international Think Tank workshop. The serious game focused on three particular aspects of CCA and DRR policy interactions: (1) separation of administrative responsibilities and the use of different terminology, (2) the ongoing competition for funding and political will as well as (3) difficulties regarding the top-down implementation of policies. The rules and design process are presented briefly, before going in-depth into the information gleaned during its application in the workshop.

Description: The Arctic region is especially impacted by global warming as temperatures in high latitude regions have increased and are predicted to further rise at levels above the global average. This is crucial to Arctic soils and the shallow shelves of the Arctic Ocean as they are underlain by permafrost. Perennially frozen ground is a habitat for a large number and great diversity of viable microorganisms, which can remain active even under freezing conditions. Warming and thawing of permafrost makes trapped soil organic carbon more accessible to microorganisms. They can transform it to the greenhouse gases carbon dioxide, methane and nitrous oxide. On the other hand, it is assumed that thawing of the frozen ground stimulates microbial activity and carbon turnover. This can lead to a positive feedback loop of warming and greenhouse gas release. Submarine permafrost covers most areas of the Siberian Arctic Shelf and contains a large though unquantified carbon pool. However, submarine permafrost is not only affected by changes in the thermal regime but by drastic changes in the geochemical composition as it formed under terrestrial conditions and was inundated by Holocene sea level rise and coastal erosion. Seawater infiltration into permafrost sediments resulted in an increase of the pore water salinity and, thus, in thawing of permafrost in the upper sediment layers even at subzero temperatures. The permafrost below, which was not affected by seawater, remained ice-bonded, but warmed through seawater heat fluxes. The objective of this thesis was to study microbial communities in submarine permafrost with a focus on their response to seawater influence and long-term warming using a combined approach of molecular biological and physicochemical analyses. The microbial abundance, community composition and structure as well as the diversity were investigated in drill cores from two locations in the Laptev Sea, which were subjected to submarine conditions for centuries to millennia. The microbial abundance was measured through total cell counts and copy numbers of the 16S rRNA gene and of functional genes. The latter comprised genes which are indicative for methane production (mcrA) and sulfate reduction (dsrB). The microbial community was characterized by high-throughput-sequencing of the 16S rRNA gene. Physicochemical analyses included the determination of the pore water geochemical and stable isotopic composition, which were used to describe the degree of seawater influence. One major outcome of the thesis is that the submarine permafrost stratified into different so-called pore water units centuries as well as millennia after inundation: (i) sediments that were mixed with seafloor sediments, (ii) sediments that were infiltrated with seawater, and (iii) sediments that were unaffected by seawater. This stratification was reflected in the submarine permafrost microbial community composition only millennia after inundation but not on time-scales of centuries. Changes in the community composition as well as abundance were used as a measure for microbial activity and the microbial response to changing thermal and geochemical conditions. The results were discussed in the context of permafrost temperature, pore water composition, paleo-climatic proxies and sediment age. The combination of permafrost warming and increasing salinity as well as permafrost warming alone resulted in a disturbance of the microbial communities at least on time-scales of centuries. This was expressed by a loss of microbial abundance and bacterial diversity. At the same time, the bacterial community of seawater unaffected but warmed permafrost was mainly determined by environmental and climatic conditions at the time of sediment deposition. A stimulating effect of warming was observed only in seawater unaffected permafrost after millennia-scale inundation, visible through increased microbial abundance and reduced amounts of substrate. Despite submarine exposure for centuries to millennia, the community of bacteria in submarine permafrost still generally resembled the community of terrestrial permafrost. It was dominated by phyla like Actinobacteria, Chloroflexi, Firmicutes, Gemmatimonadetes and Proteobacteria, which can be active under freezing conditions. Moreover, the archaeal communities of both study sites were found to harbor high abundances of marine and terrestrial anaerobic methane oxidizing archaea (ANME). Results also suggested ANME populations to be active under in situ conditions at subzero temperatures. Modeling showed that potential anaerobic oxidation of methane (AOM) could mitigate the release of almost all stored or microbially produced methane from thawing submarine permafrost. Based on the findings presented in this thesis, permafrost warming and thawing under submarine conditions as well as permafrost warming without thaw are supposed to have marginal effects on the microbial abundance and community composition, and therefore likely also on carbon mobilization and the formation of methane. Thawing under submarine conditions even stimulates AOM and thus mitigates the release of methane.

Description: Die globale Erwärmung beeinträchtigt die Arktische Region besonders stark. Im Vergleich zum globalen Mittel sind die Temperaturen in den hohen Breitengraden am stärksten gestiegen und werden voraussichtlich auch weiterhin am stärksten ansteigen. Das ist äußerst kritisch, da arktische Böden und die flachen Schelfgebiete des Arktischen Ozeans von Permafrost geprägt sind. Dieser mehrjährig gefrorene Boden ist ein Habitat für eine große Anzahl und Diversität von Mikroorganismen, die lebensfähig sind und auch unter gefrorenen Bedingungen aktiv sein können. Einerseits machen eine Erwärmung und das Tauen des Permafrosts gespeicherten organischen Kohlenstoff zugänglicher für die Mikroorganismen. Diese können den Kohlenstoff in die Treibhausgase Kohlenstoffdioxid, Methan und Distickstoffoxid umwandeln. Andererseits stimuliert das Tauen des gefrorenen Bodens die mikrobielle Aktivität und den Kohlenstoffumsatz. Das kann zu einem sich verstärkenden Rückkopplungsprozess aus Erwärmung und Freisetzung von Treibhausgasen führen. Submariner Permafrost umfasst den größten Teil des Ostsibirischen Arktisschelfs und enthält ein großes, wenn auch nicht quantifiziertes Kohlenstoffreservoir. Der submarine Permafrost wird jedoch nicht nur durch Veränderungen des Wärmehaushalts beeinflusst, sondern auch durch drastische Veränderungen in der geochemischen Zusammensetzung. Durch den holozänen Meeresspiegelanstieg und durch Küstenerosion wurde der unter terrestrischen Bedingungen gebildete Permafrost überflutet. Ein Eindringen von Meerwasser führte in den Permafrostsedimenten zu einem Anstieg der Porenwasser-Salinität und dadurch zum Tauen des Permafrosts in den oberen Schichten, sogar bei Temperaturen unter 0 °C. Tiefer liegende Permafrostsedimente, die (noch) nicht vom Meerwasser beeinflusst wurden, blieben eis-gebunden, aber begannen sich durch den Wärmestrom des Meerwassers zu erwärmen. Das Ziel dieser Dissertation war es, die mikrobiellen Gemeinschaften in submarinem Permafrost zu untersuchen. Der Fokus lag dabei auf der Reaktion der Gemeinschaften auf den Einfluss des Meerwassers und die Langzeiterwärmung. Die Arbeit nutzt dafür einen kombinierten Ansatz aus molekularbiologischen und physikochemischen Analysen. Die mikrobielle Abundanz, Gemeinschaftszusammensetzung und -struktur sowie die Diversität wurden in Sedimentbohrkernen zweier Standorte in der Laptew See untersucht, welche seit Jahrhunderten bis Jahrtausenden submarinen Bedingungen ausgesetzt waren. Die mikrobielle Abundanz wurde mit Hilfe von Zellzahlen und Kopienzahlen des 16S rRNA Gens sowie funktioneller Gene bestimmt, die kennzeichnend für die Methanproduktion (mcrA) und Sulfatreduktion (dsrB) sind. Die mikrobielle Gemeinschaft wurde mit Hilfe der Hochdurchsatz-Sequenzierung des 16S rRNA Gens charakterisiert. Physikochemische Analysen beinhalteten die Untersuchung der geochemischen Zusammensetzung der Porenwassers und der stabilen Wasserisotopen. Beide Zusammensetzungen wurden genutzt, um den Grad des Meerwassereinflusses auf die Permafrostsedimente zu beschreiben. Ein Hauptergebnis der Arbeit ist, dass sich submariner Permafrost sowohl nach Jahrhunderten als auch nach Jahrtausenden der Überflutung in verschiedene Schichten, sogenannte Porenwassereinheiten, unterteilen lässt: (i) Sedimente, die sich mit dem Meeresboden vermischt haben, (ii) Sedimente, die vom Meerwasser infiltriert wurden und (iii) Sedimente, die vom Meerwasser unbeeinflusst sind. Diese Schichtenbildung spiegelt sich erst nach jahrtausendelanger Überflutung auch in der mikrobiellen Gemeinschaftszusammensetzung wider, nicht jedoch nach Jahrhunderten. Änderungen sowohl in der Gemeinschaftszusammensetzung als auch in der Abundanz wurden als Maß für mikrobielle Aktivität und die mikrobielle Reaktion auf die sich ändernden thermischen und geochemischen Bedingungen genutzt. Die Ergebnisse wurden im Kontext von Permafrosttemperatur, Porenwasserzusammensetzung, paleoklimatischen Proxys und dem Sedimentalter diskutiert. Die Kombination aus Permafrosterwärmung und steigender Salinität, sowie die Permafrosterwärmung allein, resultierten auf Zeitskalen von Jahrhunderten in einer Störung der mikrobiellen Gemeinschaft. Dies drückte sich durch einen Verlust der mikrobiellen Abundanz und der bakteriellen Diversität aus. Gleichzeitig wurde die bakterielle Gemeinschaft im vom Meerwasser unbeeinflussten, aber erwärmten Permafrost hauptsächlich durch die Umweltbedingungen und das Klima zur Zeit der Sedimentablagerung geprägt. Ein stimulierender Einfluss der Erwärmung konnte im vom Meerwasser unbeeinflussten Permafrost erst nach jahrtausendelanger Überflutung beobachtet werden. Dies wurde durch einen Anstieg in der mikrobiellen Abundanz und einer Abnahme der organischen Substrate sichtbar. Obwohl die bakteriellen Gemeinschaften des Permafrostes submarinen Bedingungen für Jahrhunderte bis Jahrtausende ausgesetzt waren, unterschieden sie sich kaum von den Gemeinschaften im terrestrischen Permafrost. Die Gemeinschaft des submarinen Permafrosts wurde von Phyla wie Actinobacteria, Chloroflexi, Firmicutes, Gemmatimonadetes und Proteobacteria dominiert, welche auch unter gefrorenen Bedingungen aktiv sein können. Darüber hinaus enthielten die archaellen Gemeinschaften an beiden Standorten eine hohe Anzahl von marinen und terrestrischen anaerob methan-oxidierenden Archaeen (ANME), bei denen eine Aktivität unter in situ Bedingungen bei Minusgraden angenommen wird. Eine Modellierung zeigte, dass die anaerobe Oxidation von Methan (AOM) potenziell fast die gesamte Menge des gespeicherten und mikrobiell produzierten Methans in tauendem submarinem Permafrost reduzieren könnte. Die Ergebnisse der Arbeit deuten darauf hin, dass das Tauen von Permafrost unter submarinen Bedingungen sowie eine Erwärmung ohne Tauen marginale Effekte auf die Abundanz und Zusammensetzung der mikrobiellen Gemeinschaften und somit wahrscheinlich auch auf die Mobilisierung von Kohlenstoff in Form von Methan hat. Das Tauen unter submarinen Bedingungen stimuliert sogar AOM und reduziert somit den Ausstoß von Methan.

Description: Real time in-situ microscopy imaging of surface structure and atom dynamics of heterogeneous catalysts is an important step for understanding reaction mechanisms. Here, using in-situ environmental transmission electron microscopy (ETEM), we directly visualize surface atom dynamics at manganite perovskite catalyst surfaces for oxygen evolution reaction (OER), which are ≥20 times faster in water than in other ambients. Comparing (001) surfaces of La0.6Sr0.4MnO3 and Pr0.67Ca0.33MnO3 with similar initial manganese valence state and OER activity, but very different OER stability, allows us to distinguish between reversible surface adatom dynamics and irreversible surface defect chemical reactions. We observe enhanced reversible manganese adatom dynamics due to partial solvation in adsorbed water for the highly active and stable La0.6Sr0.4MnO3 system, suggesting that aspects of homogeneous catalysis must be included for understanding the OER mechanism in heterogeneous catalysis.

Description: Each spring many plants put on new leaves and/or open their flowers creating a “green-wave” that can be tracked using phenological data. Various phenological datasets can be used to study spring onset at continental to global scales. Here we present a novel exploratory analysis where we link two multi-decadal and high-spatial resolution datasets: temperature-based phenological indices and land surface phenological metrics derived from satellite images. Our exploratory analysis, illustrated with data for the conterminous US, focuses on identifying regions with similar spring onset, and on mapping the coherence between these phenological products. Our results show that the spring onset patterns captured by the satellite are more complex than the ones identified using temperature-based phenological indices. They also highlight areas with stable and unstable spring onsets (i.e., areas that tend to remain or change of phenoregion from year to year). Finally, our results reveal that temperature-based indices are both positively and negatively correlated with the phenological information that can be derived from satellites. This opens the door to the definition of rules to integrate multi-source phenological data. To cope with the computational challenges of analyzing big geospatial rasters, we executed our analysis on a cloud platform running Apache Spark and various of its extensions (e.g., Geotrellis, SparkMLlib). This platform performed well and allowed the execution of user-tailored analyses. Hence, we believe that our computational platform paves the path towards the efficient analysis of global vegetation phenology at very high spatial resolution and, more generally, to the analysis of the ever-increasing collections of geospatial data about our planet.

Description: We analyze the spatiotemporal evolution of seismicity during a sequence of moderate (an Mw 4.7 foreshock and Mw 5.8 mainshock) earthquakes occurring in September 2019 at the transition between a creeping and a locked segment of the North Anatolian fault in the central Sea of Marmara, northwest Turkey. To investigate in detail the seismicity evolution, we apply a matched‐filter technique to continuous waveforms, thus reducing the magnitude threshold for detection. Sequences of foreshocks preceding the two largest events are clearly seen, exhibiting two different behaviors: a long‐term activation of the seismicity along the entire fault segment and a short‐term concentration around the epicenters of the large events. We suggest a two‐scale preparation phase, with aseismic slip preparing the mainshock final rupture a few days before, and a cascade mechanism leading to the nucleation of the mainshock. Thus, our study shows a combination of seismic and aseismic slip during the foreshock sequence changing the strength of the fault, bringing it closer to failure.

Description: We apply a spectral decomposition approach to isolate the source spectra from propagation and site effects and, in turn, to estimate the source parameters of small‐to‐moderate earthquakes that occurred in central Italy. The data set is composed of about 400,000 waveforms relevant to 4111 earthquakes in the moment magnitude range 1.5–6.5, recorded by a high‐density network of stations installed in the study area. We first investigate the reliability of the source parameters for small magnitudes through numerical simulations. We generate synthetic spectra for different source scaling models and near‐surface attenuation effects, considering the source–station geometry and the data availability of the central Italy data set. Our analysis with synthetics shows that the spectral decomposition is effective in isolating the source contributions from other factors. Moreover, the analysis of the residual distributions suggests that moment magnitude 1.8 is the lower bound for the retrieval of reliable Brune’s source parameters, although we observe an increase of residual’s variability below magnitude 3, and the estimated source parameters could be biased below magnitude 2.3. Remarkably, the assessment of the stress drop Δσ for small events is strongly hampered by site‐specific attenuation near the surface. In view of the results with synthetics, we analyze the source parameters of earthquakes recorded in central Italy. The corner frequency versus seismic moment relationship describes a source scaling in which Δσ increases with increasing moment magnitude Mw⁠, the mean Δσ varying from 0.1 MPa for Mw〈2 to 7.9 MPa for Mw〉5⁠. In particular, Δσ increases mainly for Mw in the ranges 2.5–3 and 4.5–5.2. The corner frequencies estimated from the apparent source spectra do not show any dependence on hypocentral distance and magnitude, confirming that uncorrected anelastic attenuation effects do not significantly bias the results.

Description: During the past 150 yr, the city of Almaty (formerly Verny) in Kazakhstan has suffered significant damage due to several large earthquakes. The 9 June 1887 Mw 7.3 Verny earthquake occurred at a time when the city mainly consisted of adobe buildings with a population of 30,000, with it being nearly totally destroyed with 300 deaths. The 3 January 1911 Mw 7.8 Kemin earthquake caused 390 deaths, with 44 in Verny itself. Remarkably, this earthquake, which occurred around 40 km from Verny, caused significant soil deformation and ground failure in the city. A crucial step toward preparing for future events, mitigating against earthquake risk, and defining optimal engineering designs, involves undertaking site response studies. With regard to this, we investigate the possibility that the extreme ground failure observed after the 1911 Kemin earthquake could have been enhanced by the presence of a shallow frozen ground layer that may have inhibited the drainage of pore pressure excess through the surface, therefore inducing liquefaction at depth. We make use of information collected regarding the soil conditions around the city at the time of the earthquakes, the results from seismic noise analysis, borehole data, and surface temperature data. From these datasets, we estimated the necessary parameters for evaluating the dynamic properties of the soil in this area. We successively characterize the corresponding sediment layers at the sites of the observed liquefaction. Although the estimated soil parameters are not optimally constrained, the dynamic analysis, carried out using selected strong‐motion recordings that are expected to be compatible with the two considered events, indicated that the extensive ground failure that occurred during the Kemin event could be due to the presence of a superficial frozen soil layer. Our results indicate that for this region, possible seasonal effects should, therefore, be considered when undertaking site effect studies.

Description: In this study, we investigate the dependencies between ground-motion intensity measures (GMIM) and earthquake magnitudes (M), in order to evaluate the dynamic stress parameter (Δσ) magnitude scaling. To achieve this, two types of datasets are used: a large subset ofthe NGA-West 2 (next generation attenuation) dataset including 1700 records from 426 sites and 271 earthquakes. The other datasets are generated through the stochastic method (Boore 2003)assuming various magnitude dependencies (constant and variable) of the stress parameter with magnitude. Adaptive neuro-fuzzy inference systems (ANFIS) are used to derive datadriven ground-motion prediction models (Ameur et al. 2018). Stiff soil (Vs30 〉 500 m/s) data are selected and the ground-motion models are depending on two input parameters: the moment magnitude (Mw)and thehypocentral distance (Rhyp). Following Molkenthin et al. (2014), we assume that Δσ is the dominating controlling factor of GMIM for stiff site conditions at Rhyp = 30 km, at the frequency (f) = 3.33 Hz for moderate earthquakes in the magnitude range Mw = [4.5–6.5]. This study confirms that the relations between magnitude and stress parameter control the scaling of ground motions. We show that the magnitude-dependent stress drops better fit the latest generation of NGA-West 2 datasets and empirical ground-motion equations. We finally calibrate a relation between dynamic stress parameter and earthquake magnitude in the magnitude range Mw =[4.5–6.5].

Description: This article explores the implementation of the Natural Resources Canada’s Fifth Generation national seismic hazard model as developed for the National Building Code of Canada (NBCC), within the OpenQuake-engine. It also describes the reconciliation of the differences in hazard estimates relative to the published NBCC values, calculated using GSCFRISK. Source and ground-motion input models developed for the GSCFRISK software were translated to the OpenQuake-engine format for the hazard comparison. In order to successfully undertake this process, several adjustments to the OpenQuake code were needed to mimic the behavior of GSCFRISK. This required the development of new functions for earthquake-rupture scaling and ground-motion interpolation. Hazard values estimated using the OpenQuake-engine are generally in good agreement with the 2015 NBCC national-scale hazard values, with differences less than 2%–3% typically achieved. Where larger differences arise, they can be rationalized in terms of differences between the behaviors of the two software engines with respect to earthquake-rupture length uncertainty and maximum ground-motion integration distance.

Description: The Carpentaria province (McArthur basin and Mount Isa inlier) in northern Australia is one of the most important districts for clastic-dominated (CD-type) massive sulfide deposits. The George Fisher Zn-Pb-Ag deposit, located in this province, is hosted by the carbonaceous Urquhart Shale Formation (ca. 1654 Ma) in a region that has an active history of metamorphism and tectonism. In this study, paragenetically constrained pyrite in samples from the George Fisher deposit and unmineralized Urquhart Shale have been analyzed in situ using secondary ion mass spectrometry (SIMS) of sulfur isotopes (δ34S values). Samples were taken from four drill cores through the main orebodies at George Fisher and one drill core through correlative, unmineralized Urquhart Shale (Shovel Flats area). Five generations of pyrite were identified at George Fisher and record a protracted history of sulfate reduction under diagenetic and subsequent hydrothermal conditions: (1) fine-grained, subhedral-spheroidal pyrite (Py-0), (2) coarse-grained, anhedral pyrite (Py-1) associated with ore-stage 1 sphalerite and galena, (3) coarse-grained, euhedral pyrite (Py-2) associated with ore-stage 2 sphalerite, galena, and pyrrhotite, (4) massive subhedral to euhedral pyrite (Py-3) associated with ore-stage 3 chalcopyrite, pyrrhotite, galena, and sphalerite, and (5) coarse-grained euhedral pyrite (Py-euh), which occurs only in unmineralized rocks. In the unmineralized Shovel Flats drill core, only Py-0 and Py-euh are present. Whereas pre-ore pyrite (Py-0) preserves negative δ34S values (–8.1 to 11.8‰), the ore-stage pyrites (Py-1, Py-2, and Py-3) have higher δ34S values (7.8–33.3, 1.9–12.7, and 23.4–28.2‰, respectively). The highest δ34S values (7.2–33.9‰) are preserved in Py-euh. In combination with petrographic observations, the δ34S values of pyrite provide evidence of three different processes responsible for the reduction of sulfate at George Fisher. Reduced sulfur in fine-grained pyrite (Py-0) formed via microbial sulfate reduction (MSR) under open-system conditions prior to the first generation of hydrothermal pyrite (Py-1) in ore-stage 1, which most likely formed via thermochemical sulfate reduction (TSR). During deformation, previously formed sulfide phases were then recycled and replaced during a second hydrothermal event (ore-stage 2), resulting in intermediate sulfur isotope values. Another syndeformational hydrothermal Cu event, involving a sulfate-bearing fluid, formed ore-stage 3 via TSR. This study demonstrates that the fine-grained pyrite formed pre-ore under conditions open to sulfate and outlines the role of multiple stages of sulfide formation in producing high-grade Zn-Pb-Ag orebodies in the Mount Isa inlier.

Description: Methane is an important greenhouse gas contributing to global climate change. Natural environments and restored wetlands contribute a large proportion to the global methane budget. Methanogenic archaea (methanogens) and methane oxidizing bacteria (methanotrophs), the biogenic producers and consumers of methane, play key roles in the methane cycle in those environments. A large number of studies revealed the distribution, diversity and composition of these microorganisms in individual habitats. However, uncertainties exist in predicting the response and feedback of methane-cycling microorganisms to future climate changes and related environmental changes due to the limited spatial scales considered so far, and due to a poor recognition of the biogeography of these important microorganisms combining global and local scales. With the aim of improving our understanding about whether and how methane-cycling microbial communities will be affected by a series of dynamic environmental factors in response to climate change, this PhD thesis investigates the biogeographic patterns of methane-cycling communities, and the driving factors which define these patterns at different spatial scales. At the global scale, a meta-analysis was performed by implementing 94 globally distributed public datasets together with environmental data from various natural environments including soils, lake sediments, estuaries, marine sediments, hydrothermal sediments and mud volcanos. In combination with a global biogeographic map of methanogenic archaea from multiple natural environments, this thesis revealed that biogeographic patterns of methanogens exist. The terrestrial habitats showed higher alpha diversities than marine environments. Methanoculleus and Methanosaeta (Methanothrix) are the most frequently detected taxa in marine habitats, while Methanoregula prevails in terrestrial habitats. Estuary ecosystems, the transition zones between marine and terrestrial/limnic ecosystems, have the highest methanogenic richness but comparably low methane emission rates. At the local scale, this study compared two rewetted fens with known high methane emissions in northeastern Germany, a coastal brackish fen (Hütelmoor) and a freshwater riparian fen (Polder Zarnekow). Consistent with different geochemical conditions and land-use history, the two rewetted fens exhibit dissimilar methanogenic and, especially, methanotrophic community compositions. The methanotrophic community was generally under-represented among the prokaryotic communities and both fens show similarly low ratios of methanotrophic to methanogenic abundances. Since few studies have characterized methane-cycling microorganisms in rewetted fens, this study provides first evidence that the rapid and well re-established methanogenic community in combination with the low and incomplete re-establishment of the methanotrophic community after rewetting contributes to elevated sustained methane fluxes following rewetting. Finally, this thesis demonstrates that dispersal limitation only slightly regulates the biogeographic distribution patterns of methanogenic microorganisms in natural environments and restored wetlands. Instead, their existence, adaption and establishment are more associated with the selective pressures under different environmental conditions. Salinity, pH and temperature are identified as the most important factors in shaping microbial community structure at different spatial scales (global versus terrestrial environments). Predicted changes in climate, such as increasing temperature, changes in precipitation patterns and increasing frequency of flooding events, are likely to induce a series of environmental alterations, which will either directly or indirectly affect the driving environmental forces of methanogenic communities, leading to changes in their community composition and thus potentially also in methane emission patterns in the future.…

Description: Methan ist ein wichtiges Treibhausgas, das zum globalen Klimawandel beiträgt. Bedeutend für das globale Methanbudget sind unter anderem natürliche und wiedervernäßte Moore. Methanogene Archaeen (Methanogene) und Methan-oxidierende Bakterien (Methanotrophe) sind die biogenen Produzenten und Konsumenten von Methan. Daher nehmen sie global, und speziell in Mooren, eine Schlüsselrolle für das Methanbudget ein. Eine Vielzahl von Studien hat die Verteilung, Vielfalt und Zusammensetzung dieser Mikroorganismen in einzelnen Lebensräumen untersucht. Es bestehen jedoch Unsicherheiten in der Vorhersage, wie sie auf den globalen Wandel und auf die damit verbundenen Umweltveränderungen reagieren werden. Diese Unsicherheiten basieren unter anderem auf bislang fehlenden biogeographischen Untersuchungen, die globale und lokale Skalen kombinieren, und auf einem unzureichenden Verständnis dazu, ob und welche Umweltfaktoren speziell methanogene Gemeinschaften beeinflussen. Zudem gibt es trotz der Bedeutung von Projekten zur Moorwiedervernässung für das regionale und globale Treibhausgasbudget nahezu keine Untersuchungen zur Zusammensetzung und Verbreitung von methanogenen und methanotrophen Gemeinschaften in degradierten wiedervernäßten, eutrophen Niedermooren. Das Ziel dieser Doktorarbeit ist es, unser Verständnis zur Reaktion der am Methanbudget beteiligten mikrobiellen Gemeinschaften auf den globalen Wandel und auf die damit einhergehenden Umweltänderungen zu verbessern. Die Arbeit untersucht daher zum einen die biogeographischen Muster methanogener Gemeinschaften und die ihnen zugrunde liegenden Umweltfaktoren auf verschiedenen räumlichen Skalen. Auf globaler Ebene wurde eine Meta-Analyse durchgeführt, die auf 94 global verteilten, öffentlichen Sequenzdatensätzen sowie den dazugehörigen Umweltdaten aus verschiedenen natürlichen Ökosystemen basiert. Hierzu gehören Böden, Seesedimente, Ästuare, marine Sedimente, hydrothermale Sedimente und Schlammvulkane. In Kombination mit einer globalen biogeographischen Karte zur Verbreitung methanogener Archaeen konnte diese Arbeit zeigen, dass biogeographische Muster von Methanogenen existieren. Terrestrische Ökosysteme zeigen zudem eine höhere Diversität als marine Ökosysteme. Ästuare, Übergangszonen zwischen marinen und terrestrischen/ limnischen Ökosystemen, weisen die größte methanogene Diversität bei jedoch vergleichsweise geringen Methanemissionen auf. Methanoculleus und Methanosaeta (Methanothrix) sind die am häufigsten nachgewiesenen Taxa in marinen Lebensräumen, während Methanoregula in terrestrischen Ökosystemen dominiert. Auf lokaler Ebene wurden in dieser Arbeit zwei wiedervernässte, eutrophe Niedermoore im Nordosten Deutschlands verglichen, das von der Ostsee beeinflusste „Hütelmoor“ und das Durchströmungsmoor „Polder Zarnekow“. Beide Moore sind durch hohe Methanemissionen infolge der Wiedervernässung charakterisiert. Einhergehend mit unterschiedlichen geochemischen Bedingungen und unterschiedlicher Nutzungshistorie weisen diese beiden wiedervernässten Standorte in ihrer Zusammensetzung unterschiedliche methanogene und methanotrophe Gemeinschaften auf lokaler Ebene auf. Zudem ist die Gruppe der Methanotrophen innerhalb der prokaryotischen Gemeinschaften jeweils unterrepräsentiert und beide Moore zeigen ein vergleichbar niedriges Verhältnis von Methanotrophen im Vergleich zu Methanogenen. Diese Arbeit liefert erste Hinweise darauf, dass die schnelle und erfolgreiche Wiederbesiedlung durch Methanogene in Kombination mit einer offenbar schlecht etablierten methanotrophen Gemeinschaft zu den erhöhten Methanflüssen in beiden Mooren nach Wiedervernässung beiträgt. Abschließend zeigt diese Arbeit, dass eine eingeschränkte Migration („dispersal limitation“) die biogeographischen Verteilungsmuster von Methanogenen in natürlichen Ökosystemen kaum beeinflusst. Stattdessen werden Vorkommen und Anpassung von methanogenen Gemeinschaften vor allem durch den selektiven Druck verschiedener Umweltbedingungen reguliert. Die Umweltparameter Salzgehalt, pH-Wert und Temperatur wurden dabei als wichtigste Faktoren identifiziert, die die Verbreitung methanogener Gemeinschaften global bzw. speziell in terrestrischen Standorten beeinflussen. Es ist daher wahrscheinlich, dass prognostizierte Klimaveränderungen wie steigende Temperatur, Änderungen der Niederschlagsmuster und zunehmende Häufigkeit von Überschwemmungsereignissen zu Änderungen in der Zusammensetzung methanogener Gemeinschaften führen, die möglicherweise auch die Methanemissionsmuster beeinflussen werden.…

Description: In the light of the November 30th, 2018 (N30) earthquake activity, some neighborhoods of the city of Buenos Aires were shaken by a 3.8 mb earthquake (4.53 km estimated depth). We examined the historical and recent seismic records in order to analyze possible mechanisms related to the distribution of tectonic stresses as responsible for such unusual earthquakes in a region where only very little seismic activity is reported. According to this, at list one historical event occurred on June 5th, 1888 and other small magnitude earthquakes are mentioned since 1848 interpreted as being associated with the Rio de la Plata faulting. But there is, still no consensus about the role of this structure compared to other structures with orientation SW-NE. The lack of evidence to support one over the other structures makes it difficult to analyze these earthquakes. The presence of the Quilmes Trough connecting the Santa Lucía Basin in Uruguay and the Salado Basin in Argentina was recently proposed to play a tectonic role by a system of ENE-WSW trending controlled by extensional faulting related to the beginning of the Gondwana breakup. This depocenter with a thickness of almost 2,000 m of Mesozoic and Tertiary sequences could be acting as a zone of weakness in the crust and therefore responsible for the mentioned earthquake activity. The orientation of this structure correlates well with the present convergence vector between the Nazca and the South American plates and could therefore be propitious for strain release triggering shallow intraplate seismicity. We propose that most of the epicenters from historical and recent earthquakes might be aligned sub-parallel to the principal axis of the Quilmes Trough. Nevertheless, more data is needed to produce a reliable earthquake monitoring system in order to elucidate the tectonic stress regime and the existence of such structures at depth

Description: The Earth precession-nutation model endorsed by resolutions of each the International Astronomical Union and the International Union of Geodesy and Geophysics is composed of two theories developed independently, namely IAU2006 precession and IAU2000A nutation. The IAU2006 precession was adopted to supersede the precession part of the IAU 2000A precession-nutation model and tried to get the new precession theory dynamically consistent with the IAU2000A nutation. However, full consistency was not reached, and slight adjustments of the IAU2000A nutation amplitudes at the micro arcsecond level were required to ensure consistency. The first set of formulae for these corrections derived by Capitaine et al. (Astrophys 432(1):355–367, 2005), which was not included in IAU2006 but provided in some standards and software for computing nutations. Later, Escapa et al. showed that a few additional terms of the same order of magnitude have to be added to the 2005 expressions to get complete dynamical consistency between the official precession and nutation models. In 2018 Escapa and Capitaine made a joint review of the problem and proposed three alternative ways of nutation model and its parameters to achieve consistency to certain different extents, although no estimation of their respective effects could be worked out to illustrate the proposals. Here we present some preliminary results on the assessment of the effects of each of the three sets of corrections suggested by Escapa and Capitaine (Proceedings of the Journées, des Systémes de Référence et de la Rotation Terrestre: Furthering our Knowledge of Earth Rotation, Alicante, 2018) by testing them in conjunction with the conventional celestial pole offsets given in the IERS EOP14C04 time series.

Description: This report focuses on some selected scientific outcomes of the activities developed by the IAU/IAG Joint Working Group on Theory of Earth rotation and validation along the term 2015–2019. It is based on its end-of-term report to the IAG Commission 3 published in the Travaux de l’IAG 2015–2019, which in its turn updates previous reports to the IAG and IAU, particularly the triennial report 2015–2018 to the IAU Commission A2, and the medium term report to the IAG Commission 3 (2015–2017). The content of the report has served as a basis for the IAG General Assembly to adopt Resolution 5 on Improvement of Earth rotation theories and models.

Description: Laboratory hydraulic fracturing tests on cubic granite specimens with a side length of 100 mm were performed under true triaxial stress conditions combined with acoustic emission monitoring. Six different injection schemes were applied to investigate the influence of the injection scheme on hydraulic performance and induced seismicity during hydraulic fracturing. Three of these schemes are injection rate controlled: constant rate continuous injection (CCI), stepwise rate continuous injection (SCI), and cyclic progressive injection (CPI); the other three are pressurization rate controlled: stepwise pressurization (SP), stepwise pulse pressurization (SPP) and cyclic pulse pressurization (CPP). The test results show that the SPP scheme achieves the highest increase in injectivity among the six schemes. The CPI scheme generates the lowest induced seismicity while the improvement in injectivity is the least pronounced. The CPP scheme allows increasing injectivity and decreasing induced seismicity, and is suggested as a promising alternative injection scheme for field applications. Thin section microscopic observations of fractured specimens show that intragranular fractures splitting microcline, orthoclase and quartz grains dominate the hydraulic fractures independent of the injection scheme. The SPP scheme creates the largest fracture length, which explains the highest injectivity value among all schemes. Tests with relatively low magnitude of maximum AE amplitude correspond to short fracture length and small portions of intragranular fractures in microcline grains. Quartz grains are more fractured than microcline and orthoclase grains, and quartz chips (natural proppants) are frequently observed adjacent to hydraulic fractures. The laboratory test results show the potential for hydraulic fracture growth control in field applications by advanced fluid injection schemes, i.e. cyclic pulse pressurization of granitic rock mass.

Description: After large earthquakes at subduction zones, the plate interface continues moving due to mostly frictional afterslip or simply afterslip processes. Below approximately 60 km depth, the seismic moment release at the plate interface is quite small indicating that the shear strength is low and stable sliding is the prevailing process. This agrees with the lack of significant interseismic locking at deeper segments (〉60 km) resulting from the inversion of geodetic data and thus low afterslip can be expected. However, inversion models that employ linear viscoelastic mantle rheology and an elastic crust result in significant afterslip at depths 〉60 km. In this paper, we present a combination of a 3D forward geomechanical model with power-law rheology that simulates postseismic relaxation with dislocation creep processes in the crust and upper mantle and an afterslip inversion. We estimate the cumulative viscoelastic relaxation and the afterslip distribution for the first six years following the 2010 Mw 8.8 Maule earthquake in Chile. The cumulative afterslip distribution is obtained from the inversion of the residual surface displacements between the observed displacements from the continuous GPS (cGPS) and the ones from the forward modelling. We investigate five simulations, four with different dislocation creep parameters for the crust, slab, and upper mantle and one with elastic properties for the crust and slab, and a linear viscoelastic upper mantle for comparison. Our preferred simulation considers a weak crust since it shows the best fit to the cumulative cGPS postseismic displacements, a good fit to the time-series, and, in particular, a good spatial correlation between afterslip and aftershock activity. In this simulation, most of the viscoelastic relaxation occurs in the continental lower crust beneath the volcanic arc due to dislocation creep processes. The resulting afterslip pattern from the inversion is reduced at depths 〉60 km, which correlates to the low cumulative seismic moment that is released from aftershocks at these depths. Furthermore, the cumulative afterslip moment release from this simulation corresponds to 10% of the main shock in six years, which is approximately half of the moment release that results from models with an elastic crust and linear viscosity in the upper mantle. We conclude that an integrated analysis by considering power-rheology with dislocation creep processes in the continental crust and upper mantle along with aftershock activity may be used to constrain location and magnitude postseismic relaxation processes better.

Description: Onsite earthquake early warning (EEW) systems exploit predictive models relating features extracted over the P-wave window to S-wave ground-motion parameters. These models are usually calibrated considering recordings from multiple stations and combining datasets from different regions under the ergodic assumption. Here, we show that the local-site conditions can play a significant role in determining the performance of onsite EEW predictive models in terms of rates of false or missed alerts. Interestingly, if partially nonergodic models are implemented, as done in probabilistic seismic hazard analysis, the negative impact of local-site amplifications can be mitigated. We explore the influence of site effects for onsite EEW predictive models calibrated between the peak displacement (Pd) and integral squared velocity (Iv2) measured over a 3 s P-wave window, and the acceleration response spectra (RSA) at nine different periods T (T=0.1, 0.15, 0.2, 0.3, 0.5, 0.75, 1.0, 1.5, and 2.0 s). We consider 58 earthquakes with magnitudes between Mw 3.7 and 6.5, belonging to the 2016–2017 central Italy seismic sequence that have been recorded by 100 accelerometer stations at hypocentral distances lesser than 150 km. We implement a mixed-effects regression analysis to explore the variability of the ground motion in terms of RSA predicted at different sites by considering two different group levels: in the first, each station is considered separately; in the second, we consider the Eurocode 8 (EC8, 2004) soil classification. Considering a probabilistic alert decision module applied to data from two selected stations, we show that the predictive models including site effects provide more reliable alerts, reducing the false alarms from 2.6% to 0.53% and the missed alarms from 10.1% to 4.8%. The residuals analysis shows that including a site-specific random effect in the predictive model contributes to reducing the apparent aleatory variability, whereas grouping data by EC8 classification does not provide significant benefit for EEW purposes.

Description: Ocean‐bottom seismographs (OBSs) are used to obtain seismic recordings offshore and are an increasingly important tool for investigating the globe. However, because OBS data cannot be time stamped using Global Positioning System (GPS) during deployment, correction for drift of the internal clock is required. This time drift is typically derived by synchronizing the clock before and after deployment. Linear correction is then applied using the timing deviation between GPS and the instrument’s internal clock at recovery, that is, the skew measurement. If synchronization measurements are missing, ambient noise cross‐correlation functions (CCFs) are commonly used for time correction. When investigating recordings from a small‐scale OBS network located on the Mohn’s mid‐ocean ridge, we observed a remaining drift on the skew‐corrected data. After recalculating the drift of the raw data using CCFs, we found that the skew‐based time correction was incorrect. This was also verified with the observation of teleseismic P‐wave arrivals. We describe a method to obtain properly time‐corrected data and discuss the OBS timing issues in detail. The results shown were obtained using a software package that we developed for this specific purpose and made available as open‐source software. Although we cannot explain the technical reason for the failure of skew correction, this study shows that skew corrections should not be trusted alone, and OBS timing should always be verified by either ambient noise correlations or P‐wave arrival times.

Description: In December 2018, at the conclusion of its second implementation phase, the Global Earthquake Model (GEM) Foundation released its first version of a map outlining the spatial distribution of seismic hazard at a global scale. The map is the result of an extensive, joint effort combining the results obtained from a collection of probabilistic seismic hazard models, called the GEM Mosaic. Together, the map and the underlying database of models provide an up-to-date view of the earthquake threat globally. In addition, using the Mosaic, a synopsis of the current state-of-practice in modeling probabilistic seismic hazard at national and regional scales is possible. The process adopted for the compilation of the Mosaic adhered to the maximum extent possible to GEM’s principles of collaboration, inclusiveness, transparency, and reproducibility. For each region, priority was given to seismic hazard models either developed by well-recognized national agencies or by large collaborative projects involving local scientists. The version of the GEM Mosaic presented herein contains 30 probabilistic seismic hazard models, 14 of which represent national or sub-national models; the remainder are regional-scale models. We discuss the general qualities of these models, the underlying framework of the database, and the outlook for the Mosaic’s utility and its future versions.

Description: Ground response analyses (GRA) model the vertical propagations of SH waves through flat-layered media (1DSH) and are widely carried out to evaluate local site effects in practice. Horizontal-to-vertical spectral ratio (HVSR) technique is a cost-effective approach to extract certain site-specific information, e.g., site fundamental frequency (f0), but HVSR values cannot be directly used to approximate the levels of S-wave amplifications. Motivated by the work of Kawase et al. (2019), we propose a procedure to correct earthquake HVSR amplitudes for direct amplification estimations. The empirical correction compensates HVSR by generic vertical amplification spectra categorized by the vertical fundamental frequency (f0v) via k-means clustering. In this investigation, we evaluate the effectiveness of the corrected HVSR in approximating observed linear amplifications in comparison with 1DSH modellings. We select a total of 90 KiK-net (Kiban Kyoshin network) surface-downhole sites which are found to have no velocity contrasts below their boreholes and thus of which surface-to-borehole spectral ratios (SBSRs) can be taken as their empirical transfer functions (ETFs). 1DSH-based theoretical transfer functions (TTFs) are computed in the linear domain considering uncertainties in VS profiles through randomizations. Five goodness-of-fit metrics are adopted to gauge the closeness between observed (ETF) and predicted (i.e., TTF and corrected HVSR) amplifications in both amplitude and spectral shape over frequencies from f0 to 25 Hz. We find that the empirical correction to HVSR is highly effective and achieves a “good match” in both spectral shape and amplitude at the majority of the 90 KiK-net sites, as opposed to less than one-third for the 1DSH modelling. In addition, the empirical correction does not require a velocity model, which GRAs require, and thus has great potentials in seismic hazard assessments.

Description: Probabilistic assessment of seismic hazard and risk over a geographical region presents the modeler with challenges in the characterization of the site amplification that are not present in site-specific assessment. Using site-to-site residuals from a ground motion model fit to observations from the Japanese KiK-net database, correlations between measured local amplifications and mappable proxies such as topographic slope and geology are explored. These are used subsequently to develop empirical models describing amplification as a direct function of slope, conditional upon geological period. These correlations also demonstrate the limitations of inferring 30-m shearwave velocity from slope and applying them directly into ground motion models. Instead, they illustrate the feasibility of deriving spectral acceleration amplification factors directly from sets of observed records, which are calibrated to parameters that can be mapped uniformly on a regional scale. The result is a geologically calibrated amplification model that can be incorporated into national and regional seismic hazard and risk assessment, ensuring that the corresponding total aleatory variability reflects the predictive capability of the mapped site proxy.

Description: One of the most commonly used parameters to describe seismic attenuation is the high-frequency spectral decay parameter Kappa (κr), yet the physics behind it remain littleunderstood. A better understanding of potential factors that lead to large scatter in esti-mated values ofκrconstitutes a critical need for ground-motion modeling and seismic haz-ard assessment at large. Most research efforts to date have focused on studying the site-to-site and model-to-model variability ofκ, but the uncertainties in individualκrestima-tions associated with different events at a selected site (which we refer to as the within-station variability ofκr) remain uncharacterized. As a direct corollary, obtaining robust esti-mates of the site-specific componentκ0, and their corresponding interpretation become achallenge. To understand the sources of the variability observed inκr(andκ0) at a singlesite, we select 10 Japanese Kiban–Kyoshin network (KiK-net) downhole arrays and inves-tigate the systematic contributions from ground-motion directionality. We observe thatκrestimated from a single horizontal component is orientation dependent. In addition, theinfluence of ground-motion directionality is a function of local site conditions. We proposean orientation-independentκr-value, which is not affected either by ground-motion direc-tionality or by the events’azimuths. In addition, we find that focal depth of events used inκrcalculations affects the estimation of the regional attenuation componentκR, which, inturn, influences the within-station variability in theκ0model.

Description: This study aims to identify the best-performing site characterization proxy alternative and complementary to the conventional 30 m average shear-wave velocity VS30, as well as the optimal combination of proxies in characterizing linear site response. Investigated proxies include T0 (site fundamental period obtained from earthquake horizontal-to-vertical spectral ratios), VSz (measured average shear-wave velocities to depth z, z = 5, 10, 20 and 30 m), Z0.8 and Z1.0 (measured site depths to layers having shear-wave velocity 0.8 and 1.0 km/s, respectively), as well as Zx-infer (inferred site depths from a regional velocity model, x = 0.8 and 1.0, 1.5 and 2.5 km/s). To evaluate the performance of a site proxy or a combination, a total of 1840 surface-borehole recordings is selected from KiK-net database. Site amplifications are derived using surface-to-borehole response-, Fourier- and cross-spectral ratio techniques and then are compared across approaches. Next, the efficacies of 7 single-proxies and 11 proxy-pairs are quantified based on the site-to-site standard deviation of amplification residuals of observation about prediction using the proxy or the pair. Our results show that T0 is the best-performing single-proxy among T0, Z0.8, Z1.0 and VSz. Meanwhile, T0 is also the best-performing proxy among T0, Z0.8, Z1.0 and Zx-infer complementary to VS30 in accounting for the residual amplification after VS30-correction. Besides, T0 alone can capture most of the site effects and should be utilized as the primary site indicator. Though (T0, VS30) is the best-performing proxy pair among (VS30, T0), (VS30, Z0.8), (VS30, Z1.0), (VS30, Zx-infer) and (T0, VSz), it is only slightly better than (T0, VS20). Considering both efficacy and engineering utility, the combination of T0 (primary) and VS20 (secondary) is recommended. Further study is needed to test the performances of various proxies on sites in deep sedimentary basins.

Description: Mapping the contemporary stress field of the Mediterranean provides fundamental insights on the complexity of plate tectonic forces throughout the region and at different depths. Despite increased data availability and methodological improvements, most recent comprehensive stress field characterization across the entire Mediterranean dates back to 1995. To extend the regional stress information, we use all earthquake focal mechanisms compiled in the World Stress Map database release 2016 for a formal stress inversion. Our main goals are to (1) improve the resolution of the stress field orientation, (2) evaluate the performance of the recently refined stress inversion methodology in a tectonically complex region, (3) test the hypothesis of a depth-dependent stress orientation heterogeneity, and (4) compare different types of stress and strain observations from surface using the GPS-derived information on the strain rate tensor down to the seismogenic crust using summation of normalized seismic potencies. The obtained stress orientations generally capture the main seismotectonic features, including tectonically complex settings such as the Alpine Orogeny or the Ionian Sea. The orientation of the maximum horizontal stress SHmax tends to be uniform with depth within uncertainties while larger stress heterogeneity (quantified by means of the focal mechanism diversity and misfit angles) is found between 5 and 14 km. Both, the orientation of the largest horizontal shortening axis of the strain field from potency tensors, and horizontal strain rate tensor from GPS data are generally sub-parallel to SHmax orientation, indicating a linear stress/strain relationship and that the orientations of the co-seismic release and interseismic strain accumulation are generally consistent.

Description: Data from International Ocean Discovery Program (IODP) Expedition 371 reveal vertical movements of 1–3 km in northern Zealandia during early Cenozoic subduction initiation in the western Pacific Ocean. Lord Howe Rise rose from deep (∼1 km) water to sea level and subsided back, with peak uplift at 50 Ma in the north and between 41 and 32 Ma in the south. The New Caledonia Trough subsided 2–3 km between 55 and 45 Ma. We suggest these elevation changes resulted from crust delamination and mantle flow that led to slab formation. We propose a “subduction resurrection” model in which (1) a subduction rupture event activated lithospheric-scale faults across a broad region during less than ∼5 m.y., and (2) tectonic forces evolved over a further 4–8 m.y. as subducted slabs grew in size and drove plate-motion change. Such a subduction rupture event may have involved nucleation and lateral propagation of slip-weakening rupture along an interconnected set of preexisting weaknesses adjacent to density anomalies.

Description: This study explores a link between the long-term variations in the integral sea ice volume (SIV) in the Greenland Sea and oceanic processes. Using the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS, 1979–2016), we show that the increasing sea ice volume flux through Fram Strait goes in parallel with a decrease in SIV in the Greenland Sea. The overall SIV loss in the Greenland Sea is 113 km3 per decade, while the total SIV import through Fram Strait increases by 115 km3 per decade. An analysis of the ocean temperature and the mixed-layer depth (MLD) over the climatic mean area of the winter marginal sea ice zone (MIZ) revealed a doubling of the amount of the upper-ocean heat content available for the sea ice melt from 1993 to 2016. This increase alone can explain the SIV loss in the Greenland Sea over the 24-year study period, even when accounting for the increasing SIV flux from the Arctic. The increase in the oceanic heat content is found to be linked to an increase in temperature of the Atlantic Water along the main currents of the Nordic Seas, following an increase in the oceanic heat flux from the subtropical North Atlantic. We argue that the predominantly positive winter North Atlantic Oscillation (NAO) index during the 4 most recent decades, together with an intensification of the deep convection in the Greenland Sea, is responsible for the intensification of the cyclonic circulation pattern in the Nordic Seas, which results in the observed long-term variations in the SIV.

Description: Point cloud datasets provided by LiDAR have become an integral part in many research fields including archaeology, forestry, and ecology. Facilitated by technological advances, the volume of these datasets has steadily increased, with modern airborne laser scanning surveys now providing high-resolution, (super-)national scale, multi-terabyte point clouds. However, their wider scientific exploitation is hindered by the scarcity of open source software tools capable of handling the challenges of accessing, processing, and extracting meaningful information from massive datasets, as well as by the domain-specificity of existing tools. Here we present Laserchicken, a user-extendable, cross-platform Python tool for extracting statistical properties of flexibly defined subsets of point cloud data, aimed at enabling efficient, scalable, distributed processing of multi-terabyte datasets. We demonstrate Laserchicken’s ability to unlock these transformative new resources, e.g. in macroecology and species distribution modelling, where it is used to characterize the 3D vegetation structure at high resolution ( m) across whole countries or regions. We further discuss its potential as a domain agnostic, flexible tool that can also facilitate novel applications in other research fields.

Description: The origin, transport pathway, and spatial variability of total organic carbon (OC) in the western Himalayan glaciers are poorly understood compared to those of black carbon (BC) and dust, but it is critically important to evaluate the climatic role of OC in the region. By applying the distribution of OC activation energy; 14C activity; and radiogenic isotopes of 208Pb/204Pb, 207Pb/204Pb, and 206Pb/204Pb in glacial debris and atmospheric particulate matter (PM10 size fraction), we demonstrate that 98.3 ± 1.6 and 1.7 ± 1.6% of OC in western Himalayan glaciers are derived from biomass and petrogenic sources, respectively. The δ13C and N/C composition indicates that the biomass is a complex mixture of C3 vegetation and autochthonous photoautotrophic input modified by heterotrophic microbial activity. The data set reveals that the studied western Himalayan glacier has negligible contributions from fossil-fuel-derived particles, which contrasts to the central and eastern Himalayan glaciers that have significant contributions from fossil fuel sources. We show that this spatial variability of OC sources relates to regional differences in air mass transport pathways and precipitation regimes over the Himalaya. Moreover, our observation suggests that biomass-derived carbon could be the only primary driver of carbon-induced glacier melting in the western Himalaya.

Description: We combine numerical modeling of lithospheric extension with analysis of seismic moment release and earthquake b‐value in order to elucidate the mechanism for deep crustal seismicity and seismic swarms in the Main Ethiopian Rift (MER). We run 2D numerical simulations of lithospheric deformation calibrated by appropriate rheology and extensional history of the MER to simulate migration of deformation from mid‐Miocene border faults to ~30 km wide zone of Pliocene to recent rift floor faults. While the highest strain rate is localized in a narrow zone within the rift axis, brittle strain has been accumulated in a wide region of the rift. The magnitude of deviatoric stress shows strong variation with depth. The uppermost crust deforms with maximum stress of 80 MPa, at 8‐14 km depth stress sharply decreases to 10 MPa and then increases to a maximum of 160 MPa at ~18 km depth. These 2 peaks at which the crust deforms with maximum stress of 80 MPa or above correspond to peaks in the seismic moment release. Correspondingly, the drop in stress at 8‐14 km correlates to a low in seismic moment release. At this depth range, the crust is weaker and deformation is mainly accommodated in a ductile manner. We therefore see a good correlation between depths at which the crust is strong and elevated seismic deformation, while regions where the crust is weaker deform more aseismically. Overall the bimodal depth distribution of seismic moment release is best explained by rheology of the deforming crust.

Description: Observations of rift and rifted margin architecture suggest that significant spatial and temporal structural heterogeneity develops during the multiphase evolution of continental rifting. Inheritance is often invoked to explain this heterogeneity, such as pre‐existing anisotropies in rock composition, rheology, and deformation. Here, we use high‐resolution 3D thermal‐mechanical numerical models of continental extension to demonstrate that rift‐parallel heterogeneity may develop solely through fault network evolution during the transition from distributed to localized deformation. In our models, the initial phase of distributed normal faulting is seeded through randomized initial strength perturbations in an otherwise laterally homogeneous lithosphere extending at a constant rate. Continued extension localizes deformation onto lithosphere‐scale faults, which are laterally offset by 10’s of km and discontinuous along‐strike. These results demonstrate that rift‐ and margin‐parallel heterogeneity of large‐scale fault patterns may in‐part be a natural byproduct of fault network coalescence.

Description: Over the past few decades, azimuthal seismic anisotropy measurements have been widely used proxy to study past and present‐day deformation of the lithosphere and to characterize convection in the mantle. Beneath continental regions, distinguishing between shallow and deep sources of anisotropy remains difficult due to poor depth constraints of measurements and a lack of regional‐scale geodynamic modeling. Here, we constrain the sources of seismic anisotropy beneath Madagascar where a complex pattern cannot be explained by a single process such as absolute plate motion, global mantle flow, or geology. We test the hypotheses that either Edge‐Driven Convection (EDC) or mantle flow derived from mantle wind interactions with lithospheric topography is the dominant source of anisotropy beneath Madagascar. We, therefore, simulate two sets of mantle convection models using regional‐scale 3‐D computational modeling. We then calculate Lattice Preferred Orientation that develops along pathlines of the mantle flow models and use them to calculate synthetic splitting parameters. Comparison of predicted with observed seismic anisotropy shows a good fit in northern and southern Madagascar for the EDC model, but the mantle wind case only fits well in northern Madagascar. This result suggests the dominant control of the measured anisotropy may be from EDC, but the role of localized fossil anisotropy in narrow shear zones cannot be ruled out in southern Madagascar. Our results suggest that the asthenosphere beneath northern and southern Madagascar is dominated by dislocation creep. Dislocation creep rheology may be dominant in the upper asthenosphere beneath other regions of continental lithosphere.

Description: Rund die Hälfte der in Deutschland verbrauchten Energie entfällt auf den Wärmebedarf. Ein Großteil davon muss in urbanen Räumen bereitgestellt werden, für welche eine ortsnahe Energiebereitstellung mit geringen Transportverlusten wünschenswert erscheint. Geothermisch gewonnene Energie hat hier das Potential, eine Grundlastversorgung zu gewährleisten, birgt bei der Installation jedoch ein hohes Fündigkeitsrisiko. Die detaillierte Erkundung des Untergrundes kann dieses erheblich verringern, ist häufig jedoch nur schwer durchführbar (Akzeptanz, Genehmigung) und mit hohem finanziellem und logistischem Aufwand verbunden ist. Günstige, hochauflösende und öffentlich-akzeptierte Erkun-dungsverfahren stellen eine entscheidende Voraussetzung für die flächendeckende Erschließung und Nutzung des geothermischen Wärmepotentials urbaner Räume dar. Im Rahmen des geoPuR-Projektes soll ein 3D geologisch-petrophysikalisches Modell der Stadt Potsdam erstellt werden, welches helfen soll, Unsicherheiten in der Kenntnis des strukturellen Aufbaus des Un-tergrundes zu quantifizieren und das geothermische Fündigkeitsrisiko zu reduzieren. Basierend auf vorhandenen Erkundungsdaten, sollen die Daten zu geologischen Strukturen im Potsdamer Unter-grund unter Nutzung existierender Telekommunikationsinfrastruktur und mit Hilfe innovativer, passi-ver seismischer Erkundungsmethoden verdichtet werden. Im Zusammenspiel mit einer parallel stattfindenden konventionellen seismischen Erkundung, werden praktische Werkezeuge zur Anwendung dieser Technologie entwickelt und Anwendungs-und Auflö-sungsgrenzen für den Standort ermittelt. Die Ergebnisse von geoPuR sollen dabei helfen, Investitions-entscheidungen zur Integration geothermischer Energie in vorhandene Versorgungsnetze zu treffen und das finanzielle Risiko bei der Entwicklung einer geothermischen Ressource im innerstädtischen Bereich zu verringern. Neben dem geothermischen Explorations-Werkzeug, stellen wir Ansätze zum Verkehrs-Monitoring auf Basis derselben Technologie vor.

Description: The Victoria microplate between the Eastern and Western Branches of the East African Rift System is one of the largest continental microplates on Earth. In striking contrast to its neighboring plates, Victoria rotates counterclockwise with respect to Nubia. The underlying cause of this distinctive rotation has remained elusive so far. Using 3D numerical models, we investigate the role of pre-existing lithospheric heterogeneities in continental microplate rotation. We find that Victoria’s rotation is primarily controlled by the distribution of rheologically stronger zones that transmit the drag of the major plates to the microplate and of the mechanically weaker mobile belts surrounding Victoria that facilitate rotation. Our models reproduce Victoria’s GPS-derived counterclockwise rotation as well as key complexities of the regional tectonic stress field. These results reconcile competing ideas on the opening of the rift system by highlighting differences in orientation of the far-field divergence, local extension, and the minimum horizontal stress.

Description: We performed apatite and zircon (U-Th)/He dating on a granitic pluton that has been offset by ∼10 km by motion on the sinistral strike-slip Xiangcheng fault in SW Sichuan, SE Tibetan plateau, where the Shuoqu River incises a deep valley before joining the upper Yangtze River. Mean ZHe cooling ages range from 49.5 ± 2.2 Ma to 68.6 ± 6.0 Ma. Samples located above 3870 m yield mean apatite (U-Th)/He ages ranging from 30.6 ± 1.4 Ma to 40.6 ± 2.7 Ma, whereas samples at lower elevations range from 9.8 ± 1.3 Ma to 14.6 ± 2.7 Ma. In the same region, Cenozoic continental sediments are exposed on the flanks of deep valleys. They consist of unsorted conglomerates and sandstones that partly fill a paleotopography. The sediments were deposited during an episode of rapid sedimentation, followed by incision that varies between 0.5 and 1.2 km. Thermal and exhumational modeling of the granite thermochronometric data indicates rapid cooling during the middle Miocene that was likely related to fluvial incision. Our findings suggest that the upper Yangtze River and its tributary (Shuoqu) were connected by the middle Miocene. Our modeling also supports the idea that the exhumation pattern during the Cenozoic in the southeastern margin of the Tibetan Plateau is spatially and temporally heterogeneous.

Description: The geometry and evolution of fluvial systems are thought to be related to surface uplift. In eastern Tibet, rivers exhibit peculiar drainage patterns but how these patterns were established and their connection with the plateau uplift are still under debate. Here, we use detrital zircon U-Pb dating, bedrock (U-Th)/He thermochronometry, topographic analysis and numerical modeling to explore the paleo-drainage pattern of the Dadu and Anning Rivers, eastern Tibet. Our detrital data indicate that the Pliocene sources of sediments to the Anning River are different from the modern ones and they include a source similar to that of the modern Dadu River, implying a paleo-connection between the Dadu and the Anning Rivers and a subsequent cutoff of this connection after the deposition of the Pliocene sediments. Bedrock thermochronometric data along the Dadu River reveal rapid cooling at ∼10 Ma and a possible enhanced cooling at ∼2 Ma, which we interpret as a response to the regional plateau uplift in eastern Tibet and to the Dadu-Anning capture, respectively. Combined with topographic analysis and numerical modeling, our results indicate an Early Pleistocene capture between the Dadu and Anning Rivers, resulting in the changes in the sediment sources of the Anning River, enhanced incision of the Dadu, and the transience of the Dadu River profile. The Dadu-Anning capture is related to the motion along the active sinistral strike-slip Daliangshan fault that locally disrupts the river network. This event does not date the plateau uplift; rather, it indicates how river reorganization can effectively enhance river incision and affect landscape development independently from regional-scale uplift.

Description: Accelerograms are the primary source for characterizing strong ground motion. It is therefore of paramount interest to have high‐quality recordings free from any nonphysical contamination. Frequently, accelerograms are affected by baseline jumps and drifts, either related to the instrument and/or a major earthquake. In this work, I propose a correction method for these undesired baseline drifts based on segmented linear least squares. The algorithm operates on the integrated waveforms and combines all three instrument components to estimate a model that modifies the baseline to be at zero continuously. The procedure consists of two steps: first a suite of models with variable numbers of discontinuities is derived for all three instrument components. During this process, the number of discontinuities is reduced in a parsimonious way, for example, two very close discontinuities are merged into a single one. In the second step, the optimal model is selected on the basis of the Bayesian information criterion. I exemplify the application on synthetic waveforms with known discontinuities and on observed waveforms from a unified strong‐motion database of the Japan Meteorological Agency (JMA) and the National Research Institute for Earth Science and Disaster Prevention (NIED, Japan) networks for the major events of the 2016 Kumamoto earthquakes. After the baseline jump correction, the waveforms are furthermore corrected for displacement according to Wang et al. (2011). The resulting displacements are comparable to the Interferometric Synthetic Aperture Radar‐derived displacement estimates for the Kumamoto earthquake sequence.

Description: The steady increase of ground-motion data not only allows new possibilities but also comes with new challenges in the development of ground-motion models (GMMs). Data classification techniques (e.g., cluster analysis) do not only produce deterministic classifications but also probabilistic classifications (e.g., probabilities for each datum to belong to a given class or cluster). One challenge is the integration of such continuous classification in regressions for GMM development such as the widely used mixed-effects model. We address this issue by introducing an extension of the mixed-effects model to incorporate data weighting. The parameter estimation of the mixed-effects model, that is, fixed-effects coefficients of the GMMs and the random-effects variances, are based on the weighted likelihood function, which also provides analytic uncertainty estimates. The data weighting permits for earthquake classification beyond the classical, expert-driven, binary classification based, for example, on event depth, distance to trench, style of faulting, and fault dip angle. We apply Angular Classification with Expectation–maximization, an algorithm to identify clusters of nodal planes from focal mechanisms to differentiate between, for example, interface- and intraslab-type events. Classification is continuous, that is, no event belongs completely to one class, which is taken into account in the ground-motionmodeling. The theoretical framework described in this article allows for a fully automatic calibration of ground-motionmodels using large databases with automated classification and processing of earthquake and ground-motion data. As an example, we developed a GMM on the basis of the GMM by Montalva et al. (2017) with data from the strong-motion flat file of Bastías and Montalva (2016) with ∼2400 records from 319 events in the Chilean subduction zone. Our GMMwith the data-driven classification is comparable to the expert-classification-based model. Furthermore, the model shows temporal variations of the between-event residuals before and after large earthquakes in the region.

Description: Understanding fracturing processes and the hydromechanical relation to induced seismicity is a key question for enhanced geothermal systems (EGS). Commonly massive fluid injection, predominately causing hydroshearing, are used in large-scale EGS but also hydraulic fracturing approaches were discussed. To evaluate the applicability of hydraulic fracturing techniques in EGS, six in situ, multistage hydraulic fracturing experiments with three different injection schemes were performed under controlled conditions in crystalline rock at the A¨ spo¨ Hard Rock Laboratory (Sweden). During the experiments the near-field ground motion was continuously recorded by 11 piezoelectric borehole sensors with a sampling rate of 1 MHz. The sensor network covered a volume of 30×30×30 m around a horizontal, 28-m-long injection borehole at a depth of 410 m. To extract and characterize massive, induced, high-frequency acoustic emission (AE) activity from continuous recordings, a semi-automated workflow was developed relying on full waveform based detection, classification and location procedures. The approach extended the AE catalogue from 196 triggered events in previous studies to more than 19 600 located AEs. The enhanced catalogue, for the first time, allows a detailed analysis of induced seismicity during single hydraulic fracturing experiments, including the individual fracturing stages and the comparison between injection schemes. Beside the detailed study of the spatio-temporal patterns, event clusters and the growth of seismic clouds, we estimate relative magnitudes and b-values of AEs for conventional, cyclic progressive and dynamic pulse injection schemes, the latter two being fatigue hydraulic fracturing techniques. While the conventional fracturing leads to AE patterns clustered in planar regions, indicating the generation of a single main fracture plane, the cyclic progressive injection scheme results in a more diffuse, cloud-like AE distribution, indicating the activation of a more complex fracture network. For a given amount of hydraulic energy (pressure multiplied by injected volume) pumped into the system, the cyclic progressive scheme is characterized by a lower rate of seismicity, lower maximum magnitudes and significantly larger b-values, implying an increased number of small events relative to the large ones. To our knowledge, this is the first direct comparison of high resolution seismicity in a mine-scale experiment induced by different hydraulic fracturing schemes.