ALBERT

Beschreibung: On 12 September 2007, an Mw 8.4 earthquake occurred within the southern section of the Mentawai segment of the Sumatra subduction zone, where the subduction thrust had previously ruptured in 1833 and 1797. Traveltime data obtained from a temporary local seismic network, deployed between December 2007 and October 2008 to record the aftershocks of the 2007 event, was used to determine two-dimensional (2-D) and three-dimensional (3-D) velocity models of the Mentawai segment. The seismicity distribution reveals significant activity along the subduction interface and within two clusters in the overriding plate either side of the forearc basin. The downgoing slab is clearly distinguished by a dipping region of high Vp (8.0 km/s), which can be a traced to ∼50 km depth, with an increased Vp/Vs ratio (1.75 to 1.90) beneath the islands and the western side of the forearc basin, suggesting hydrated oceanic crust. Above the slab, a shallow continental Moho of less than 30 km depth can be inferred, suggesting that the intersection of the continental mantle with the subducting slab is much shallower than the downdip limit of the seismogenic zone despite localized serpentinization being present at the toe of the mantle wedge. The outer arc islands are characterized by low Vp (4.5–5.8 km/s) and high Vp/Vs (greater than 2.0), suggesting that they consist of fluid saturated sediments. The very low rigidity of the outer forearc contributed to the slow rupture of the Mw 7.7 Mentawai tsunami earthquake on 25 October 2010.

Beschreibung: In the framework of the Dead Sea Integrated Research project (DESIRE), 59 seismological stations were deployed in the region of the Dead Sea Basin. Twenty of these stations recorded data of sufficiently high quality between May and September 2007 to be used for ambient seismic noise analysis. Empirical Green’s functions are extracted from cross-correlations of long term recordings. These functions are dominated by Rayleigh waves, whose group velocities can be measured in the frequency range from 0.1 to 0.5 Hz. Analysis of positive and negative correlation lags of the Green’s functions makes it possible to identify the direction of the source of the incoming energy. Signals with frequencies higher than 0.2 Hz originate from the Mediterranean Sea, while low frequencies arrive from the direction of the Red Sea. Travel times of the extracted Rayleigh waves were measured between station pairs for different frequencies, and tomographically inverted to provide independent velocity models. Four such 2D models were computed for a set of frequencies, all corresponding to different sampling depths, and thus together giving an indication of the velocity variations in 3D extending to a depth of 10 km. The results show low velocities in the Dead Sea Basin, consistent with previous studies suggesting up to 8 km of recent sedimentary infill in the Basin. The complex structure of the western margin of the Basin is also observed, with sedimentary infill present to depths not exceeding 5 km west of the southern part of the Dead Sea. The high velocities associated with the Lisan salt diapir are also observed down to a depth of ~5 km. The reliability of the results is confirmed by checkerboard recovery tests.

Beschreibung: We investigate the source of the Mw 7.6 Padang earthquake by inverting three-component global positioning system (GPS) data and broad-band regional seismic-displacement waveforms. The earthquake involved oblique-reverse slip either on an E–W, south-dipping plane, or on a N–S, west-dipping plane. Finite-fault inversions indicate that the rupture primarily propagated downdip and southwest from the hypocentre, with a scalar seismic moment between 3.4 and 3.7 × 1020 N m (Mw 7.62–7.65). Analysis of the seismic and geodetic data do not allow for unique identification of the causative focal plane. Aftershock patterns strongly suggest the E–W plane was the causative focal plane, but aligned geological structures in the downgoing plate favour the N–S plane. In either case, this unusually large intraslab earthquake has moved closer to failure the deepest portion of the overlying megathrust, which last ruptured during a great earthquake more than two centuries ago and is late in its seismic cycle.

Beschreibung: [...] In this thesis it is shown that the epoch-differenced ionospheric delay correction is sufficient for estimating the tropospheric delay, e.g., the Zenith Total Delay (ZTD), from SF GPS data. Based on this result, the Satellite-specific Epoch-differenced Ionospheric Delay model (SEID) was developed. In the SEID model the ionospheric corrections for SF data are generated from the observations of surrounding reference stations equipped with DF receivers. With the derived ionospheric corrections and the SF data, pseudo L2 data are generated, which can be processed using existing GPS processing software packages without any changes. [...]

Beschreibung: Multibeam bathymetry revealed the occurrence of numerous craterlike depressions, so-called pockmarks, on the sea floor of the Hammerfest Basin and the Loppa High, south-western Barents Sea. To investigate whether these pockmarks are related to ongoing gas seepage, microbial processes associated with methane metabolism were analyzed using geochemical, biogeochemical and microbiological techniques. Gravity cores were collected along transects crossing individual pockmarks, allowing a direct comparison between different locations inside (assumed activity center), on the rim, and outside of a pockmark (reference sites). Concentrations of hydrocarbons in the sediment, particularly methane, were measured as headspace (free) gas, and in the occluded and adsorbed gas fraction. Down to a depth of 2.6 m below sea floor (mbsf) sulfate reduction rates were quantified by radiotracer incubations. Concentrations of dissolved sulfate in the porewater were determined as well. Neither the sulfate profiles nor the gas measurements show any evidence of microbial activity or active fluid venting. Methane concentrations and sulfate reduction rates were extremely low or even below the detection limit. The results show that the observed sediment structures are most likely paleo-pockmarks, their formation probably occurred during the last deglaciation.

Beschreibung: The guidebook contains a thematic description an background information for each field day. The overall setting and development of the Saxo-Thuringian zone within the Variscan orogen is presented in Kroner and Romer (2010). This material is not included in this guide book (because of copyright reasons) and will be handed out to field trip participants as separate handout.

Beschreibung: Film 2: "Geological Conditions and Capacities" (Length 06:00) "Porous rocks with good permeability have, in Germany and world-wide, the highest potential for geological CO2 storage. ..." Where do these rocks occur? And which further criteria need potential CO2 storage sites to meet? Production Year: 2010-2012

Beschreibung: A damaging and widely felt moderate earthquake (Mw 6.4) hit the rural, mountainous region of southwestern Pakistan on October 28, 2008. The main shock was followed by another earthquake of identical magnitude (Mw 6.4) on the next day. The spatial distribution of aftershocks and focal mechanism revealed a NW–SE striking rupture with right-lateral strike-slip motion which is sympathetic to the NNW–SSE striking active mapped Urghargai Fault. The occurrence of strike-slip earthquakes suggests that along with the thrust faults, strike slip faults too are present beneath the fold-and-thrust belt of Sulaiman–Kirthar ranges and accommodates some of the relative motion of the Indian and Eurasian plates. To assess the characteristics of this sequence, the statistical parameters like aftershocks temporal decay, b-value of G–R relationship, partitioning of radiated seismic energy due to aftershocks, and spatial fractal dimension (D-value) have been examined. The b-value is estimated as 1.03 ± 0.42 and suggests the tectonic genesis of the sequence and crustal heterogeneity within rock mass. The low p-value of 0.89 ± 0.07 implies slow decay of aftershocks activity which is probably an evidence for low surface heat flow. A value of spatial fractal dimension of 2.08 ± 0.02 indicates random spatial distribution and that the source is a two-dimensional plane filled-up by fractures. The static coseismic Coulomb stress changes due to the foreshock (Mw 5.3) were found to increase stress by more than 0.04 bars at the hypocenter of the main shock, thus promoting the failure. The cumulative coseismic Coulomb stress changes due to the foreshock and mainshocks suggest that most of the aftershocks occurred in the region of increased Coulomb stress, and to the SE to the mainshock rupture.

Beschreibung: Information on soil surface state is valuable for many applications such as climate studies and monitoring of permafrost regions. C-band scatterometer data indicate good potential to deliver information on surface freeze/thaw. Variation in state or amount of water contained in the soil causes significant alteration of dielectric properties of the soil which is markedly observable in scatterometer backscattered signal. A threshold-analysis method is developed to derive a set of parameters to be used in evaluating the normalized backscatter measurements through decision trees and anomaly detection modules for determination of freeze/thaw conditions. The model parameters are extracted from two years (2007-2008) backscatter data from ASCAT scatterometer onboard Metop satellite collocated with ECMWF ReAnalysis (ERA-Interim) soil temperature. Backscatter measurements are flagged as indicator of frozen/unfrozen surface, and snowmelt or existing water on the surface. The output product, so-called surface state flag (SSF), compares well with two modeled soil temperature data sets as well as the air temperature measurements from synoptic meteorological stations across the northern hemisphere. The SSF time series are also validated with soil temperature data available at four in situ observation sites in Siberian and Alaska regions showing the overall accuracy of about 80% to 90%.

Beschreibung: In 2004 and 2005 a passive seismic experiment was carried out in the northern and northeastern part of the Bohemian Massif (Sudetes) to study the lithospheric structure. We present results from Ps and Sp receiver function analyses. With one exception, Moho depth at stations in the northwestern part of the study area varies between 28 and 32 km. Thicker crust up to 35 km was mapped toward the south (Moldanubian unit) and toward the east (Moravo–Silesian and Brunovistulian units) confirming results from previous active seismic measurements. There exists a relatively sharp step in Moho depth between units of the central Sudetes (~ 30 km) and the Moravo–Silesian unit (~ 35 km). The vp/vs ratios inverted from primary and multiple Moho Ps conversions hint for different crustal compositions of the units. Toward the Carpathian thrust we have no clear indications for any crustal root or slab beneath the western Carpathians. However, our data suggests a deepening of the Moho or at least a complicated crust–mantle transition in this area. Additional Ps phases were observed between 6 and 10 s delay time in the Sudetes. These phases cannot be explained by Moho reverberations, but are most probably caused by low velocity zones in the middle crust or lithospheric mantle as shown by modeling of theoretical receiver functions. The stations showing these abnormal phases are located in the area of Permo-Carboniferous basins on probably Teplá–Barrandian crust. Therefore we assume that the phases hint at a mid-crustal low velocity zone between 16 and 20 km depth, which is interpreted as a felsic solidified magma reservoir of the Permo-Carboniferous volcanism beneath the Sudetic Basins. Sp receiver functions show phases with negative polarity at 9 to 12 s lead time on average, which we interpret as lithosphere–asthenosphere boundary at about 80 to 110 km depth.

Beschreibung: The chilean part of the subduction zone between the Nazca and South American plates is an ideal laboratory to understand the seismic and aseismic processes that take place on such a plate boundary. For instance, measuring the elastic deformation of the upper plate during the interseismic loading phase using GPS can help assessing the degree of locking between both plates. We calculate the kinematic coupling coefficient using a simple elastic modeling in which a backslip motion is applied on a buried dislocation in a semi-infinite elastic half-space. During this PhD, my aim was to obtain the coupling distribution along the entire chilean trench (18 ◦ S-38 ◦ S) and to compare it to seismotectonic segmentation of the megathrust. Therefore I collected all the previously published interseismic velocities and combined them into a single coherent data set. New data were also collected and processed since 2009 on new or renovated campaign networks. We obtain a new data set that covers almost all the subduction zone on more than ahundred benchmarks. Those data were used to map precisely the coupling distribution on the interface. Coupling strongly varies both along strike and along dip and draws a segmentation of the megathrust. The highly coupled segments correlate well with the rupture zones of historical megathrustearthquakes and intersegments, that are low coupled areas, correlate with zones that behave as barriers to the seismic propagation. Furthermore, intersegments often correlate with anomalies in the coastline (bays, peninsulas), subducting bathymetric features (ridges, fracture zones) and with a high-rate of moderate-magnitude subduction earthquakes. The Maule earthquake that occurred on February 27, 2010 ruptured a highly locked segment and stopped in low coupled intersegment areas. This earthquake gave us new insights on the relationship between apparent coupling coefficient and mechanical behavior of the subduction interface. Therefore, coupling maps should help estimating the seismic hazard along the Chilean subduction zone. In particular, we show here that the North Chile seismic gap is not formed of one single highly coupled segment and that it is cut in two by a large intersegment zone where coupling is low around Iquique. Finally, Loa, Paranal and Atacama highly coupled segments are identified as zones that may rupture alone with a Mw〉8 subduction earthquake, or with a megathrust earthquake in case of collective rupture, and where the seismic hazard is high. La zone de subduction entre les plaques Nazca et Amérique du Sud constitue, aux latitudesdu Chili, un laboratoire naturel d’exception pour étudier les processus qui permettent d’accommoder la convergence sur l’interface de subduction. En particulier, la mesure par GPS de la déformation de la plaque supérieure pendant la phase intersismique sur la subduction permet de quantifier l’intensité du blocage sur l’interface via le coefficient de couplage cinématique. Ce dernier peut être déterminé en utilisant un modèle de dislocation simple dans un milieu homogène élastique sur laquelle on applique la théorie du backslip. Cette thèse a pour objectif de déterminer la valeur de ce couplage intersismique au long de la subduction chilienne (18 ◦ S-38 ◦ S) et d’analyser ces variations en relation avec la segmentation sismotectonique et la sismicité historique. Pour cela, les vitesses intersismiques collectées au cours de ces 20 dernières années ont été combinées dans un même référentiel et de nouvelles données GPS ont été acquises sur des réseaux installés ou rénovés par les équipes franco-chiliennes depuis 2009. Cet effort instrumental associé au travail de traitement des données que j’ai réalisé conduit à un jeu de vitesses intersismiques sur plusieurs centaines de points et quasi continu sur la marge chilienne. Ces données ont été utilisées pour élaborer une cartographie précise du couplage au long de la subduction chilienne. La distribution de couplage qui est présentée dans ce manuscrit montre d’importantes variations latérales et en profondeur de la valeur du couplage et dessine ainsi une segmentation de la marge. Les segments fortement couplés semblent corrélés aux grandes ruptures historiques, tandis que les intersegments découplés semblent se comporter comme des barrières à leur propagation. Les zones d’intersegments correspondent à des zones atypiques de la subduction, souvent associées à des anomalies du trait de côte (baies, péninsules), à l’entrée en subduction de structures bathymétriques (rides, fractures) et à une sismicité de fond importante. Le séisme de Maule du 27 février 2010 (Mw 8.8) qui a rompu un segment fortement couplé et qui s’est arrêté dans des zones de faible couplage a permis de proposer un lien entre le couplage apparent et le comportement mécanique de l’interface.Sur la base de cette analyse, il semble possible d’utiliser les cartes de couplage intersismique pour mieux estimer l’aléa sismique au Chili. Dans ce travail, nous apportons notamment un éclairage nouveau sur la lacune du Grand Nord Chili en montrant que le segment couplé du Loaest nettement plus restreint que la lacune en elle-même et qu’un large intersegment découplé s’y développe autour d’Iquique. Une attention particulière est donc portée aux régions de l’Atacama, du Paranal et du Loa qui correspondent à des zones très fortement couplées, chacune susceptibles de produire un grand séisme de subduction potentiellement associé à un tsunami, et un séisme géant en cas de rupture collective.

Beschreibung: La zone de subduction entre les plaques Nazca et Amérique du Sud constitue, aux latitudesdu Chili, un laboratoire naturel d’exception pour étudier les processus qui permettent d’accommoder la convergence sur l’interface de subduction. En particulier, la mesure par GPS de la déformation de la plaque supérieure pendant la phase intersismique sur la subduction permet de quantifier l’intensité du blocage sur l’interface via le coefficient de couplage cinématique. Ce dernier peut être déterminé en utilisant un modèle de dislocation simple dans un milieu homogène élastique sur laquelle on applique la théorie du backslip. Cette thèse a pour objectif de déterminer la valeur de ce couplage intersismique au long de la subduction chilienne (18 ◦ S-38 ◦ S) et d’analyser ces variations en relation avec la segmentation sismotectonique et la sismicité historique. Pour cela, les vitesses intersismiques collectées au cours de ces 20 dernières années ont été combinées dans un même référentiel et de nouvelles données GPS ont été acquises sur des réseaux installés ou rénovés par les équipes franco-chiliennes depuis 2009. Cet effort instrumental associé au travail de traitement des données que j’ai réalisé conduit à un jeu de vitesses intersismiques sur plusieurs centaines de points et quasi continu sur la marge chilienne. Ces données ont été utilisées pour élaborer une cartographie précise du couplage au long de la subduction chilienne. La distribution de couplage qui est présentée dans ce manuscrit montre d’importantes variations latérales et en profondeur de la valeur du couplage et dessine ainsi une segmentation de la marge. Les segments fortement couplés semblent corrélés aux grandes ruptures historiques, tandis que les intersegments découplés semblent se comporter comme des barrières à leur propagation. Les zones d’intersegments correspondent à des zones atypiques de la subduction, souvent associées à des anomalies du trait de côte (baies, péninsules), à l’entrée en subduction de structures bathymétriques (rides, fractures) et à une sismicité de fond importante. Le séisme de Maule du 27 février 2010 (Mw 8.8) qui a rompu un segment fortement couplé et qui s’est arrêté dans des zones de faible couplage a permis de proposer un lien entre le couplage apparent et le comportement mécanique de l’interface. Sur la base de cette analyse, il semble possible d’utiliser les cartes de couplage intersismique pour mieux estimer l’aléa sismique au Chili. Dans ce travail, nous apportons notamment un éclairage nouveau sur la lacune du Grand Nord Chili en montrant que le segment couplé du Loa est nettement plus restreint que la lacune en elle-même et qu’un large intersegment découplé s’y développe autour d’Iquique. Une attention particulière est donc portée aux régions de l’Atacama, du Paranal et du Loa qui correspondent à des zones très fortement couplées, chacune susceptibles de produire un grand séisme de subduction potentiellement associé à un tsunami, et un séisme géant en cas de rupture collective.

Beschreibung: Several projects initiated and coordinated by the Helmholtz Centre Potsdam ‐ GFZ German Research Centre for Geosciences focus on shale gas and may serve as entry points for the understanding of general features for efficient shale-gas production, not only in Europe. The integrated research on European shale gas started by launching the prominent Gas Shales in Europe project (GASH) in 2009 and slightly earlier in 2008 the GeoEnergie project (GeoEn). The Herald Tribune declared in August 2008 “Europe starting search for shale gas”. New on the agenda is the ESOP initiative (European Sustainable Operating Practices) which addresses environmental concerns.

Beschreibung: Film 5: "Ketzin Pilot Site" (Length 05:05) "At the Ketzin pilot site in Brandenburg, Germany, CO2 has been injected into an underground storage formation since June, 2008. ...". The monitoring methods used at the pilot site Ketzin are among the most comprehensive in the field of CO2 storage worldwide. Important is the combination of different monitoring methods, each with different temporal and spatial resolutions. Which methods are used? And what have we already learned? Production Year: 2011-2012

Beschreibung: Estimating reliable depths for shallow seismic sources is important in both seismo-tectonic studies and in seismic discrimination studies. Surface wave excitation is sensitive to source depth, especially at intermediate and short-periods, owing to the approximate exponential decay of surface wave displacements with depth. A new method is presented here to retrieve earthquake source parameters from regional and teleseismic intermediate period (100–15 s) fundamental-mode surface wave recordings. This method makes use of advances in mapping global dispersion to allow higher frequency surface wave recordings at regional and teleseismic distances to be used with more confidence than in previous studies and hence improve the resolution of depth estimates. Synthetic amplitude spectra are generated using surface wave theory combined with a great circle path approximation, and a grid of double–couple sources are compared with the data. Source parameters producing the best-fitting amplitude spectra are identified by minimizing the least-squares misfit in logarithmic amplitude space. The F-test is used to search the solution space for statistically acceptable parameters and the ranges of these variables are used to place constraints on the best-fitting source. Estimates of focal mechanism, depth and scalar seismic moment are determined for 20 small to moderate sized (4.3 ≤Mw≤ 6.4) earthquakes. These earthquakes are situated across a wide range of geographic and tectonic locations and describe a range of faulting styles over the depth range 4–29 km. For the larger earthquakes, comparisons with other studies are favourable, however existing source determination procedures, such as the CMT technique, cannot be performed for the smaller events. By reducing the magnitude threshold at which robust source parameters can be determined, the accuracy, especially at shallow depths, of seismo-tectonic studies, seismic hazard assessments, and seismic discrimination investigations can be improved by the application of this methodology.

Beschreibung: We generated medium-range forecasts of runoff for a 50 km2 headwater catchment upstream of a reservoir using numerical weather predictions (NWPs) of the past as input to an operational hydrological model. NWP data originating from different sources were tested. For a period of 8.5 years, we computed daily forecasts with a lead time of +120 h based on an empirically downscaled version of the ECMWF’s ensemble prediction system. For the last 3.5 years of the test period, we also tried the deterministic COSMO-EU forecast disseminated by the German Weather Service for lead times of up to +72 h. Common measures of skill indicate superiority of the ensemble runoff forecast over single-value forecasts for longer lead times. However, regardless of which NWP data were being used, the probability of event detection (POD) was found to be generally lower than 50%. In many cases, values in the range of 20–30% were obtained. At the same time, the false alarms ratio (FAR) was often found to be considerably high. The observed uncertainties in the hydrological forecasts were shown to originate from both the insufficient quality of precipitation forecasts as well as deficiencies in hydrological modeling and quantitative precipitation estimation. With respect to the anticipatory control of reservoirs in the studied catchment, the value of the tested runoff forecasts appears to be limited. This is due to the unfavorably low POD/FAR ratio in conjunction with a high cost–loss ratio. However, our results indicate that, in many cases, major runoff events related to snow melt can be successfully predicted as early as 4–5 days in advance.

Beschreibung: In May 2012, a seismic sequence struck the Emilia region (northern Italy). The mainshock, of Ml 5.9, occurred on May 20, 2012, at 02:03 UTC. This was preceded by a smaller Ml 4.1 foreshock some hours before (23:13 UTC on May 19, 2012) and followed by more than 2,500 earthquakes in the magnitude range from Ml 0.7 to 5.2. In addition, on May 29, 2012, three further strong earthquakes occurred, all with magnitude Ml ≥5.2: a Ml 5.8 earthquake in the morning (07:00 UTC), followed by two events within just 5 min of each other, one at 10:55 UTC (Ml 5.3) and the second at 11:00 UTC (Ml 5.2). For all of the Ml ≥4.0 earthquakes in Italy and for all of the Ml ≥4.5 in the Mediterranean area, an automatic procedure for the computation of a regional centroid moment tensor (RCMT) is triggered by an email alert. Within 1 h of the event, a manually revised quick RCMT (QRCMT) can be published on the website if the solution is considered stable. In particular, for the Emilia seismic sequence, 13 QRCMTs were determined and for three of them, those with M 〉5.5, the automatically computed QRCMTs fitted the criteria for publication without manual revision. Using this seismic sequence as a test, we can then identify the magnitude threshold for automatic publication of our QRCMTs.

Beschreibung: The Tafilalt region, located at the eastern end of the Anti-Atlas chain in Morocco, was shaken on 23 and 30 October 1992 by two moderate earthquakes of magnitude mb ∼ 5 and intensity ∼ VI MSK64, which caused two deaths and great damage in the area between Erfoud and Rissani. The review of data available on the seismic crisis allowed us to improve the knowledge on the macroseismic, instrumental and source parameters of the earthquakes. The main results of the present study are: (1) location of the epicentres with the help of data from a close portable network allowed us to propose new epicentral coordinates at 31.361° N, 4.182° W (23 October) and 31.286° N, 4.347° W (30 October); both events have focal depths of 2 km; (2) the shock of 30 October was followed by a series of 305 aftershocks, most of which were located west of Rissani; the 61 best-constrained events had focal depths of 5 to 19 km and magnitudes 0.7 to 3; (3) the largest damage was located in an area between the two epicentres within the Tafilalt valley and was probably amplified by site effects due to the proximity of the water table within the Quaternary sediments; (4) focal mechanisms of the main events correspond to strike-slip faulting with fault planes oriented N–S (left lateral) and E–W (right lateral); the only mechanism available for the aftershocks also corresponds to strike-slip faulting; (5) spectral analysis shows that the scalar seismic moment (Mo) of the first event is slightly larger than the second; the corresponding values of Mw are 5.1 and 5.0, respectively; (6) the dimensions of the faults for a circular fault model are 7.7 ± 1.4 and 7.4 ± 1.2 km, respectively; the average displacement is 4 cm for the first event and 3.7 cm for the second; the stress drop is 0.4 and 0.3 MPa, respectively, in agreement with standard values; (7) the Coulomb Stress test performed for both earthquakes suggests a relationship between both events only when the used location is at the limit of the horizontal uncertainty; (8) finally, the occurrence of these shocks suggests that the Anti-Atlas is undergoing tectonic deformation in addition to thermal uplift as suggested by recent publications.

Beschreibung: The Mw=6.3 deep-focus earthquake beneath Granada, Spain, in 2010 consisted of three resolvable sub-events occurring within a time span of 5 s. Estimated sub-event seismic moment partitioning is 12%, 7% and 81%, respectively. All sub-events had similar focal mechanisms with a vertical and a near-horizontal nodal plane, and all occurred within 5 km of each other at a similar depth, suggesting rupture on the near-horizontal nodal plane. However, directivity analyses indicate that the first sub-event ruptured unilaterally on the vertical plane. Its modeled rupture length of ∼9 km and stress drop of ∼2 MPa are typical of crustal earthquakes. In contrast, the following sub-events show no clear directivity. The third, best resolved, sub-event had a hypocenter ∼2 km from the first and a focal mechanism indistinguishable from the first, but it had a rupture dimension of 〈6.5 km and a stress drop of 〉40 MPa. This requires an ambient stress field significantly greater than the stress drop of the first sub-event, implying that the first sub-event ruptured as a slip pulse with a transient weakening mechanism. The large stress drops of the second and third sub-events suggest a crack-like rupture without fault healing and with nearly total stress drop. Fault-zone melting and metastable olivine are viable mechanisms for these ruptures. In contrast, the rupture characteristics of the first sub-event seem incompatible with most mechanisms currently under consideration for deep-focus earthquakes.

Beschreibung: The focus of this study is the high- resolution localization of more than 800 earthquakes in the Northern Chilean Salar Grande region at about 21S within the Andean Costal Cordillera. The events have been recorded by a temporary local network in 2010. We find, that seismicity is not only related to the Nazca slab but also occurs widely scattered within the overlying continental crust. Our highly resolved locations with typical uncertainties below 200 meters image two distinct seismogenic zones at the top and deeper within the mantle of the Nazca slab, as well as the prominent Atacama Fault Zone. The latter could eventually penetrate the entire crust, possibly joining the subduction interface at a depth of about 40 kilometers. In our further investigation, we have applied a waveform cross-correlation approach by which we were able to identify clusters of similar events with respect to location and source mechanism. Within these clusters we took advantage of waveform similarity to further decrease location uncertainties. Most of the crustal seismicity clusters locate on a subvertical planar structure beneath the surface traces of the Atacama Fault Zone, which extends from close to the surface down to the slab. This could indicate that seismicity in the forearc is not only caused by subduction- related deformation, but also by fluid processes. The irregular spatial distribution of the Nazca slab related clusters may be a consequence of topographic variations within the downgoing slab.

Beschreibung: The Indian Tsunami Early Warning Centre (ITEWC) in Hyderabad monitored the 11 April 2012 tsunami off the coast of Sumatra, which was generated by a shallow strike–slip earthquake and it largest aftershock of magnitude Mw (mB) 8.5 and 8.2 respectively, that occurred inside the subducting slab of the Indian plate. The earthquake generated a small ocean-wide tsunami that has been recorded by various tide gauges and tsunami buoys located in the Indian Ocean region. ITEWC detected the earthquake within 3 min 52 s and issued six advisories (bulletins) according to its Standard Operating Procedure. The ITEWC performed well during the event, and avoided false alarms and unnecessary public evacuations, especially in the mainland part of India region.

Beschreibung: We present a new, S-velocity model of the European upper mantle, constrained by inversions of seismic waveforms from broad-band stations in Europe and surrounding regions. We collected seismograms for the years 1990–2007 from all permanent stations in Europe for which data were available. In addition, we incorporated data from temporary experiments. Automated multimode inversion of surface and S-wave forms was applied to extract structural information from the seismograms, in the form of linear equations with uncorrelated uncertainties. The equations were then solved for seismic velocity perturbations in the crust and mantle with respect to a 3-D reference model with a realistic crust. We present two versions of the model: one for the entire European upper mantle and another, with the highest resolution, focused on the upper 200 km of the mantle beneath western and central Europe and the circum Mediterranean. The mantle lithosphere and asthenosphere are well resolved by both models. Major features of the lithosphere–asthenosphere system in Europe and the Mediterranean are indentified. The highest velocities in the mantle lithosphere of the East European Craton (EEC) are found at about 150 km depth. There are no indications for a deep cratonic root below about 330 km depth. Lateral variations within the cratonic mantle lithosphere are resolved as well. The locations of kimberlites correlate with reduced S-wave velocities in the shallow cratonic mantle lithosphere. This anomaly is present in regions of both Proterozoic and Archean crust, pointing to an alteration of the mantle lithosphere after the formation of the craton. Strong lateral changes in S-wave velocity are found at the northwestern margin of the EEC and may indicate erosion of cratonic mantle lithosphere beneath the Scandes by hot asthenosphere. The mantle lithosphere beneath western Europe and between the Tornquist–Teisseyre Zone and the Elbe Line shows moderately high velocities and is of an intermediate character, between cratonic lithosphere and the thin lithosphere of central Europe. In central Europe, Caledonian and Variscian sutures are not associated with strong lateral changes in the lithosphere–asthenosphere system. Cenozoic anorogenic intraplate volcanism in central Europe and the circum Mediterranean is found in regions of shallow asthenosphere and close to changes in the depth of the lithosphere–asthenosphere boundary. Very low velocities at shallow upper-mantle depths are present from eastern Turkey towards the Dead Sea transform fault system and Sinai, beneath locations of recent volcanism. Low-velocity anomalies extending vertically from shallow upper mantle down to the transition zone are found beneath the Massif Central, Sinai and the Dead Sea, the Canary Islands and Iceland.

Beschreibung: Earthquake moment tensors reflecting seven years of global seismic activity (2004–2010) are presented. The results are the product of the global centroid-moment-tensor (GCMT) project, which maintains and extends a catalog of global seismic moment tensors beginning with earthquakes in 1976. Starting with earthquakes in 2004, the GCMT analysis takes advantage of advances in the mapping of propagation characteristics of intermediate-period surface waves, and includes these waves in the moment-tensor inversions. This modification of the CMT algorithm makes possible the globally uniform determination of moment tensors for earthquakes as small as MW = 5.0. For the period 2004–2010, 13,017 new centroid-moment tensors are reported.

Beschreibung: The Indian Tsunami Early Warning System (ITEWS) at the Indian National Centre for Ocean Information Services, Hyderabad, is responsible for issuing tsunami bulletins in India. The tsunami centre operates on a 24 × 7 basis and monitors seismological stations, bottom pressure recorders and tidal stations throughout the Indian Ocean to evaluate potentially tsunamigenic earthquakes and disseminating tsunami bulletins. The end-to-end capabilities of this warning system have been well proven during all the tsunami-genic earthquakes that occurred since September 2007. Comparison of the earthquake parameters estimated by ITEWS with other international seismological agencies suggests that the system is performing well and has achieved the target set up by the Intergovernmental Oceanographic Commission.

Beschreibung: Integrated Ocean Drilling Program (IODP) Expedition 331 drilled into the Iheya North hydrothermal system in the middle Okinawa Trough in order to investigate active subseafloor microbial ecosystems and their physical and chemical settings. We drilled five sites during Expedition 331 using special guide bases at three holes for reentry, casing, and capping, including installation of a steel mesh platform with valve controls for postcruise sampling of fluids. At Site C0016, drilling at the base of the North Big Chimney (NBC) mound yielded low recovery, but core included the first Kuroko-type black ore ever recovered from the modern subseafloor.The other four sites yielded interbedded hemipelagic and strongly pumiceous volcaniclastic sediment, along with volcanogenic breccias that are variably hydrothermally altered and mineralized. At most sites, analyses of interstitial water and headspace gas yielded complex patterns with depth and lateral distance of only a few meters. Documented processes included formation of brines and vapor-rich fluids by phase separation and segregation, uptake of Mg and Na by alteration minerals in exchange for Ca, leaching of K at high temperature and uptake at low temperature, anhydrite precipitation, potential microbial oxidation of organic matter and anaerobic oxidation of methane utilizing sulfate, and methanogenesis. Shipboard analyses have found evidence for microbial activity in sediments within the upper 10–30 m below seafloor (mbsf) where temperatures were relatively low, but little evidence in the deeper hydrothermally altered zones and hydrothermal fluid regime.

Beschreibung: The disciplines of environmental protection and sustainable development are highly reliant on the continuous advancement of theoretical and practical knowledge. Germany can look back on many years of environmental and sustainability research and thus has both an opportunity and a duty to share its extensive technological and planning expertise with the rest of the world. After all, conserving the foundations of life and protecting people from natural hazards are not just domestic concerns. Three examples from the field of water management highlight the many means of imparting knowledge to young scientists across the globe.

Beschreibung: Tsunami early warning (TEW) is a challenging task as a decision has to be made within few minutes on the basis of incomplete and error-prone data. Deterministic warning systems have difficulties in integrating and quantifying the intrinsic uncertainties. In contrast, probabilistic approaches provide a framework that handles uncertainties in a natural way. Recently, we have proposed a method using Bayesian networks (BNs) that takes into account the uncertainties of seismic source parameter estimates in TEW. In this follow-up study, the method is applied to 10 recent large earthquakes offshore Sumatra and tested for its performance. We have evaluated both the general model performance given the best knowledge we have today about the source parameters of the 10 events and the corresponding response on seismic source information evaluated in real-time. We find that the resulting site-specific warning level probabilities represent well the available tsunami wave measurements and observations. Difficulties occur in the real-time tsunami assessment if the moment magnitude estimate is severely over- or underestimated. In general, the probabilistic analysis reveals a considerably large range of uncertainties in the near-field TEW. By quantifying the uncertainties the BN analysis provides important additional information to a decision maker in a warning centre to deal with the complexity in TEW and to reason under uncertainty.

Beschreibung: The scope of this Science Plan is to describe the scientific background, applications, and activities related to the EnMAP mission. Primarily, the Science Plan addresses scientists and funding institutions, but it may also be of interest for environmental stakeholders and governmental bodies. It is conceived to be a living document that will be updated throughout the whole mission. Current global challenges call for interdisciplinary approaches. Hence, the science plan is not structured in the traditional disciplinary way. Instead, it builds on overarching research themes to which EnMAP can contribute. This Science Plan comprises the following five chapters presenting the significance, background, framework, applications, and strategy of the EnMAP mission: Chapter 2 highlights the need for EnMAP data with respect to major environmental issues and various stakeholders. This chapter states the mission’s main objectives and provides a list of research themes addressing global challenges to whose understanding and management EnMAP can contribute. Chapter 3 presents an overview of the EnMAP mission from a scientific point of view including a brief description of the mission parameters, data products and access, and calibration/validation issues. Chapter 4 provides an overview of hyperspectral remote sensing regarding its principles, development, and current state and synergies to other satellite missions. Chapter 5 describes current lines of research and EnMAP applications to address the research themes presented in Chapter 2. Finally, Chapter 6 outlines the scientific exploitation strategy, which includes the strategy for community building, dissemination of knowledge and increasing public awareness.

Beschreibung: We study the scaling of spectral properties of a set of 68 aftershocks of the 2007 November 14 Tocopilla (M 7.8) earthquake in northern Chile. These are all subduction events with similar reverse faulting focal mechanism that were recorded by a homogenous network of continuously recording strong motion instruments. The seismic moment and the corner frequency are obtained assuming that the aftershocks satisfy an inverse omega-square spectral decay; radiated energy is computed integrating the square velocity spectrum corrected for attenuation at high frequencies and for the finite bandwidth effect. Using a graphical approach, we test the scaling of seismic spectrum, and the scale invariance of the apparent stress drop with the earthquake size. To test whether the Tocopilla aftershocks scale with a single parameter, we introduce a non-dimensional number, graphic, that should be constant if earthquakes are self-similar. For the Tocopilla aftershocks, Cr varies by a factor of 2. More interestingly, Cr for the aftershocks is close to 2, the value that is expected for events that are approximately modelled by a circular crack. Thus, in spite of obvious differences in waveforms, the aftershocks of the Tocopilla earthquake are self-similar. The main shock is different because its records contain large near-field waves. Finally, we investigate the scaling of energy release rate, Gc, with the slip. We estimated Gc from our previous estimates of the source parameters, assuming a simple circular crack model. We find that Gc values scale with the slip, and are in good agreement with those found by Abercrombie and Rice for the Northridge aftershocks.

Beschreibung: The transition between the lithosphere and the asthenosphere is subject to numerous contemporary studies as its nature is still poorly understood. The thickest lithosphere is associated with old cratons and platforms and it has been shown that seismic investigations may fail to image the lithosphere-asthenosphere boundary in these areas. Instead, several recent studies have proposed a mid-lithospheric discontinuity of unknown origin existing under several cratons. In this study we investigate the Tanzania craton in East Africa which is enclosed by the eastern and western branches of the East African Rift System. We present evidence from S receiver functions for two consecutive discontinuities at depths of 50–100 km and 140–200 km, which correspond to significant S wave velocity reductions under the Tanzania craton and the Albert and Edward rift segments. By comparison with synthetic waveforms we show that the lower discontinuity coincides with the LAB exhibiting velocity reductions of 6–9%. The shallower interface reveals a velocity drop that varies from 12% beneath the craton to 24% below the Albert-Edward rift. It is interpreted as an infiltration front marking the upper boundary of altered lithosphere due to ascending asthenospheric melts. This is corroborated by computing S velocity variations based on xenolith samples which exhibit a dense system of crystallized veins acting as pathways of the infiltrating melt. Mineral assemblages in these veins are rich in phlogopite and pyroxenite which can explain the reduced shear wave velocities. Melt infiltration represents a suitable mechanism to form a mid-lithospheric discontinuity within cratonic lithosphere that is underlain by anomalously hot mantle.

Beschreibung: Mineral dust is a complex entity containing a range of iron minerals including poorly crystalline to crystalline iron oxides to clay minerals. Important progress has been made to characterize iron mineralogical compositions in the dust recently. These include the quantification of the content of crystalline hematite and goethite, which appear to show a regional variation in North Africa as a result of the differences in the degree of chemical weathering. Fractional Fe solubility (dissolved to total iron, FFS) in the atmospheric aerosols has been reported to range from 0.1% to 80%. However, FFS is usually less than 0.5% in the non-atmospherically-processed dust, suggesting that FFS can be enhanced by atmospheric processes. One of the atmospheric processes, gravitational settling of dust, which has been previously hypothesized to cause the abovementioned enhancement of FFS during dust transport has been shown to be insignificant. Cycling of dust particles in the clouds, in which pH is usually higher than 4, and in the aerosol phase, in which pH is usually substantially lower, can significantly affect iron speciation and FFS. Laboratory experiments showed that a significant amount of iron (〉0.5%) can only be solubilized in the dust when pH is lower than 4. These laboratory data suggest that acid processing rather than cloud processing might be a prime mechanism to cause an increase in FFS in the dust during transport. Further laboratory studies, field measurements, and modelling are needed to increase the ability of models to quantify the atmospheric processing of iron in the dust. (c) 2012 Elsevier B.V. All rights reserved.

Beschreibung: The spectral element method, which provides an accurate solution of the elastodynamic problem in heterogeneous media, is implemented in a code, called RegSEM, to compute seismic wave propagation at the regional scale. By regional scale we here mean distances ranging from about 1 km (local scale) to 90° (continental scale). The advantage of RegSEM resides in its ability to accurately take into account 3-D discontinuities such as the sediment-rock interface and the Moho. For this purpose, one version of the code handles local unstructured meshes and another version manages continental structured meshes. The wave equation can be solved in any velocity model, including anisotropy and intrinsic attenuation in the continental version. To validate the code, results from RegSEM are compared to analytical and semi-analytical solutions available in simple cases (e.g. explosion in PREM, plane wave in a hemispherical basin). In addition, realistic simulations of an earthquake in different tomographic models of Europe are performed. All these simulations show the great flexibility of the code and point out the large influence of the shallow layers on the propagation of seismic waves at the regional scale. RegSEM is written in Fortran 90 but it also contains a couple of C routines. It is an open-source software which runs on distributed memory architectures. It can give rise to interesting applications, such as testing regional tomographic models, developing tomography using either passive (i.e. noise correlations) or active (i.e. earthquakes) data, or improving our knowledge on effects linked with sedimentary basins.

Beschreibung: On May 11th 2011, a rather small earthquake caused nine fatalities in the city of Lorca, SE-Spain. We analyze seismograms from a dense network to characterize the source of this earthquake. We estimate an oblique reverse faulting mechanism, moment magnitude of 5.2 and a shallow hypocenter (4.6 km), at only 5.5 km epicentral distance from the city center. Double difference relocations yield a ∼5 km long, NE-SW trending distribution of aftershocks SW of the mainshock, suggesting a SW propagating rupture along the Alhama de Murcia fault. We use the Mw 4.6 foreshock and an Mw 3.9 aftershock as empirical Greens functions to estimate apparent source time functions, observing a clear directivity effect. We model apparent durations with a unilateral and asymmetric bilateral rupture, in both cases obtaining rupture directivity of ∼N220°E, towards Lorca. In addition to the near epicenter and shallow depth, directivity may have contributed to the significant impact.

Beschreibung: We combine density functional theory (DFT) within the local density approximation (LDA), the quasiharmonic approximation (QHA), and a model vibrational density of states (VDoS) to calculate elastic moduli and sound velocities of γ-(Fex,Mg1−x)2SiO4 (ringwoodite), the most abundant mineral of the lower Earth's transition zone (TZ). Comparison with experimental values at room-temperature and high pressure or ambient-pressure and high temperature shows good agreement with our first-principles findings. Then, we investigate the contrasts associated with the β→γ(Fex,Mg1−x)2SiO4 transformation at pressures and temperatures relevant to the TZ. This information offers clearly defined reference values to advance the understanding of the nature of the 520 km seismic discontinuity.

Beschreibung: Local earthquake data from a dense temporary seismological network in the southern Dead Sea area have been analysed within the project DESIRE (Dead Sea Integrated Research Project). Local earthquakes are used for the first precise image of the distribution of the P-wave velocity and the vP/vS ratios. 65 stations registered 655 local events within 18 months of observation time. A subset of 530 well-locatable events with 26 730 P- and S-arrival times was used to calculate a tomographic model for the vP and vP/vS distribution. Since the study area is at first-order 2-D, a gradual approach was chosen, which compromised a 2-D inversion followed by a 3-D inversion. The sedimentary basin fill is clearly imaged through high vP/vS ratios and low vP. The basin fill shows an asymmetric structure with average depth of 7 km at the western boundary and depth between 10 and 14 km at the eastern boundary. This asymmetry is reflected by the vertical strike-slip eastern border fault, and the normal faulting at the western boundary, caused by the transtensional deformation within the last 5 Myr. Within the basin fill the Lisan salt diapir is imaged through low vP/vS ratios, reflecting its low fluid content. The extensions were determined to 12 km in E–W and 17 km in N–S direction while its depth is 5–6 km. The thickness of the pre-basin sediments below the basin fill cannot be derived from the tomography data—it is estimated to less than 3 km from former investigations. Below the basin, down to 18 km depth very low P-wave velocities and low vP/vS ratios are observed—most likely caused by fluids from the surrounding crust or the upper mantle.

Beschreibung: An approach to detect afterslips in the source process of giant earthquakes is presented in the normal-mode frequency band (0.3–2.0mHz). The method is designed to avoid a potential systematic bias problem in the determination of earthquake moment by a typical normal-mode approach. The source of bias is the uncertainties in Q (modal attenuation parameter) which varies by up to about ±10per cent among published studies. A choice of Q values within this range affects amplitudes in synthetic seismograms significantly if a long time-series of about 5–7 d is used for analysis. We present an alternative time-domain approach that can reduce this problem by focusing on a shorter time span with a length of about 1 d. Application of this technique to four recent giant earthquakes is presented: (1) the Tohoku, Japan, earthquake of 2011 March 11, (2) the 2010 Maule, Chile earthquake, (3) the 2004 Sumatra-Andaman earthquake and (4) the Solomon earthquake of 2007 April 1. The Global Centroid Moment Tensor (GCMT) solution for the Tohoku earthquake explains the normal-mode frequency band quite well. The analysis for the 2010 Chile earthquake indicates that the moment is about 7–10per cent higher than the moment determined by its GCMT solution but further analysis shows that there is little evidence of afterslip; the deviation in moment can be explained by an increase of the dip angle from 18° in the GCMT solution to 19°. This may be a simple trade-off problem between the moment and dip angle but it may also be due to a deeper centroid in the normal-mode frequency band data, as a deeper source could have steeper dip angle due to changes in geometry of the Benioff zone. For the 2004 Sumatra-Andaman earthquake, the five point-source solution by Tsai et al. explains most of the signals but a sixth point-source with long duration improves the fit to the normal-mode frequency band data. The 2007 Solomon earthquake shows that the high-frequency part of our analysis (above 1mHz) is compatible with the GCMT solution but the low-frequency part requires afterslip to explain the increasing amplitude ratios towards lower frequency. The required slip has the moment about 19per cent of the GCMT solution and the rise time of 260s. The total moment of these earthquakes are 5.31 × 1022 Nm (Tohoku), (1.86–1.96) × 1022 Nm (Chile), 1.33 × 1023 Nm (Sumatra) and 1.86 × 1021 Nm (Solomon). The moment magnitudes are 9.08, 8.78–8.79, 9.35 and 8.11, respectively, using Kanamori's original formula between the moment and the moment magnitude. However, the trade-off problem between the moment and dip angle can modify these estimates for moment up to about 40–50per cent and the corresponding magnitude ±0.1.

Beschreibung: The 11 April 2012 Mw 8.6 earthquake offshore Sumatra is the largest of the rare great intraplate earthquakes of the instrumental era. This major strike-slip event occurred in the diffuse zone of deformation that accommodates differential rotation between Indian and Australian plates. We perform a back projection analysis – calibrated with well-located aftershocks – of short-period teleseismic P-waves recorded by the European array to image the rupture process during the mainshock. In complement, a Love wave analysis is conducted for tracking azimuthal change in the apparent global source duration due to the source spatio-temporal extent. The combined analysis reveals a complex rupture pattern, characterized by three main episodes of energy release, the latest being located 370 km west of the epicenter, on the Ninety East Ridge, with a delay of 120 s. We interpret the 11 April 2012 Mw 8.6 offshore Sumatra earthquake as a complex westward-propagating sequence of dynamically triggered strike-slip fault ruptures, associated to the reactivation of the inherited NNE–striking sea floor fabric. The dynamic triggering mechanism could result from the interaction between transient surface wave stress perturbations and fluids.