ALBERT

Beschreibung: We present a new interface between the geochemical simulator PHREEQC and the open source language R. It represents a tool to flexibly and efficiently program and automate every aspect of geochemical modelling. The interface helps particularly to setup and run large numbers of simulations and visualise the results. Also profiting of numberless high-quality R extension packages, performing sensitivity analysis or Monte Carlo simulations becomes straightforward. Further, an algorithm to speedup reactive transport simulations starting from homogeneous or zone- homogeneous state is programmed and successfully evaluated through the interface. It proved effective and could therefore be included in any reactive transport simulator.

Beschreibung: We studied 40 artesian wells (AWs) in the Amu Darya Delta. These wells include high-salinity (∼ 52 g/l) and saline (5 – 24 g/l) waters but are mostly low-salinity waters (1.3 – 2.9 g/l). The low-salinity AWs cluster into three types, reflecting the variable mixing of different end-member solutes: (residual) brines and solutes deriving from silicate alteration, dissolution of limestone and dissolution of gypsum. The solutes are all undersaturated in calcite and gypsum, contain a substantial cation excess against dissolved inorganic carbon and are characterised by low Ca/SO4 ratios. On the basis of the hydrochemical mass budgets of model cases, we demonstrate that Na-rich Cl-brines (45-48%) and a Na2SO4-brine (30-47%) are the dominant solute components. The solutes derived from aluminium silicate alteration are minor components (7.3 – 19.4%). Even less important are solutes from limestone or gypsum dissolution (0.05 – 3.7%). These waters are unlikely to have originated from sediments hosting gypsum. The low-salinity AWs must have acquired their dominant hydrochemical signatures under non-equilibrium conditions between their remote (unknown) seepage areas and their discharge locations. This acquisition may have begun during the early hydrochemical groundwater evolution when meteoric or surface water passed the critical zone under an arid climate regime. Warmer saline AWs (∼40°C) hosted in deeper Cretaceous formations contain a high portion of NaCl-rich brine (85%) and some are saturated in gypsum. These waters were derived from fluids rising along faults from pre-Cretaceous strata. The high-salinity and relatively cold AWs discharge close to the retreating Aral Sea south of its western basin. These AWs are suboxic, and Si concentrations are very low. The AW hydrochemical signatures reflect the dissolution of halite and gypsum. We observed positive correlations between temperature, Br, B and Si. The temperature correlation with bromide likely documents the transformation of organically bound Br. The silica concentrations in low-salinity AWs southeast of the Aral Sea (eastern basin) are close to quartz saturation and define a chemical Si-geothermometer.

Beschreibung: We applied scaled physical analogue experiments to investigate the early development of salt diapirs induced by differential sedimentary loading in an intra-continental basin realm (e.g. the North German Basin). During the experiments, deformation in a salt-analogue viscous layer was initiated by variations in the thickness of an overlying brittle material and subsequent accumulation of the brittle material further sustained deformation. A 2D optical image correlation system was used to monitor the strain evolution in the salt analogue material. Our models indicate that the formation of salt pillow structures can be achieved by minimum variations in the overburden loading. The increase of differential loading by adding synkinematic layers in the subsided areas causes not only an active piercing of the viscous layer through the brittle overburden but also an additional uplift in the adjacent areas. These elevations, named “secondary structures”, act as origins for a successive generation of diapirs. Consequently, an initial perturbation of the salt–sediment-interface can lead to a lateral propagation temporally shifted diapirs. The linkage between primary and secondary structures is reflected in the synkinematic overburden layers such as overlapping peripheral sinks in the transition zone between two diapirs. These sinks, in turn, are a frequently observable phenomenon around salt structures of the North German basin indicating that “secondary diapirism” is an underestimated process – besides regional tectonic stresses – influencing the evolution of salt structures.

Beschreibung: On 2012 May 20 and 29, two damaging earthquakes with magnitudes Mw 6.1 and 5.9, respectively, struck the Emilia-Romagna region in the sedimentary Po Plain, Northern Italy, causing 26 fatalities, significant damage to historical buildings and substantial impact to the economy of the region. The earthquake sequence included four more aftershocks with Mw ≥ 5.0, all at shallow depths (about 7–9 km), with similar WNW–ESE striking reverse mechanism. The timeline of the sequence suggests significant static stress interaction between the largest events. We perform here a detailed source inversion, first adopting a point source approximation and considering pure double couple and full moment tensor source models. We compare different extended source inversion approaches for the two largest events, and find that the rupture occurred in both cases along a subhorizontal plane, dipping towards SSW. Directivity is well detected for the May 20 main shock, indicating that the rupture propagated unilaterally towards SE. Based on the focal mechanism solution, we further estimate the co-seismic static stress change induced by the May 20 event. By using the rate-and-state model and a Poissonian earthquake occurrence, we infer that the second largest event of May 29 was induced with a probability in the range 0.2–0.4. This suggests that the segment of fault was already prone to rupture. Finally, we estimate peak ground accelerations for the two main events as occurred separately or simultaneously. For the scenario involving hypothetical rupture areas of both main events, we estimate Mw = 6.3 and an increase of ground acceleration by 50 per cent. The approach we propose may help to quantify rapidly which regions are invested by a significant increase of the hazard, bearing the potential for large aftershocks or even a second main shock.

Beschreibung: We present regional-scale mass balances for 25 drainage basins of the Antarctic Ice Sheet (AIS) from satellite observations of the Gravity and Climate Experiment (GRACE) for the years 2002–2011. Satellite gravimetry estimates of the AIS mass balance are strongly influenced by mass movement in the Earth interior caused by ice advance and retreat during the last glacial cycle. Here, we develop an improved glacial-isostatic adjustment (GIA) estimate for Antarctica using newly available GPS uplift rates, allowing us to more accurately separate GIA-induced trends in the GRACE gravity fields from those caused by current imbalances of the AIS. Our revised GIA estimate is considerably lower than previous predictions, yielding an (upper) estimate of apparent mass change of 48 ± 18 Gt yr−1. Therefore, our AIS mass balance of −103 ± 23 Gt yr−1 is considerably less negative than previous GRACE estimates. The Northern Antarctic Peninsula and the Amundsen Sea Sector exhibit the largest mass loss (−25 ± 6 Gt yr−1 and −126 ± 11 Gt yr−1, respectively). In contrast, East Antarctica exhibits a slightly positive mass balance (19 ± 16 Gt yr−1), which is, however, mostly the consequence of compensating mass anomalies in Dronning Maud and Enderby Land (positive) and Wilkes and George V Land (negative) due to interannual accumulation variations. In total, 7% of the area constitute more than half of the AIS imbalance (53%), contributing −151 ± 9 Gt yr−1 to global mean sea-level change. Most of this imbalance is caused by long-term ice-dynamic speed up expected to prevail in the future.

Beschreibung: 3000 m of ice sheet thickness has ensured that central Greenland has kept it geothermal heat flow (GHF) distribution enigmatic. Some few direct ice temperature measurements from deep ice cores reveal a GHF of 50 to 60 mW/m2 in the Summit region and this is noticeably above what would be expected for the underlying Early Proterozoic lithosphere. In addition, indirect estimates from zones of rapid basal melting suggest extreme anomalies 15 to 30 times continental background. Subglacial topography indicates caldera like topographic features in the zones hinting at possible volcanic activity in the past [1], and all of these observations combined hint at an anomalous lithospheric structure. Further supporting this comes from new high-resolution P-wave tomography, which shows a strong thermal anomaly in the lithosphere crossing Greenland from east to west [2]. Rock outcrops at the eastern and western end of this zone indicate significant former magmatic activity, older in the east and younger in the west. Additionally, plate modelling studies suggest that the Greenland plate passed over the mantle plume that is currently under Iceland from late Cretaceous to Neogene times, consistent with the evidence from age of magmatism. Evidence of rapid basal melt revealed by ice penetrating radar along the hypocentre of the putative plume track indicates that it continues to affect the Greenland continental geotherm today. We analyse plume-induced thermal disturbance of the present-day lithosphere and their effects on the central Greenland ice sheet by using a novel evolutionary model of the climate-ice-lithosphere-upper mantle system. Our results indicate that mantle plume-induced erosion of the lithosphere has occurred, explaining caldera-type volcanic structures, the GHF anomaly, and requiring dyke intrusion into the crust during the early Cenozoic. The residual thermo-mechanical effect of the mantle plume has raised deep-sourced heat flow by over 25 mW/m2 since 60 Ma and explains the high basal melting rates of the Greenland ice sheet observed in the study area. [1] Fahnestock, M., Abdalati, W., Joughin, I., Brozena, J., Gogineni, P., 2001. High geothermal heat flow, Basal melt, and the origin of rapid ice flow in central Greenland. Science (New York, N.Y.). 294, 2338–2342. [2] Jakovlev, A.V., Bushenkova, N.A., Koulakov, I.Y., Dobretsov, N.L., 2012. Structure of the upper mantle in the Circum-Arctic region from regional seismic tomography. Russian Geology and Geophysics. 53, 963–971.

Beschreibung: We present in a statistical study a comparison of thermospheric mass density enhancements (ρrel) with electron temperature (Te), small-scale field-aligned currents (SSFACs), and vertical ion velocity (Vz) at high latitudes around noon magnetic local time (MLT). Satellite data from CHAMP (CHAllenging Minisatellite Payload) and DMSP (Defense Meteorological Satellite Program) sampling the Northern Hemisphere during the years 2002–2005 are used. In a first step we investigate the distribution of the measured quantities in a magnetic latitude (MLat) versus MLT frame. All considered variables exhibit prominent peak amplitudes in the cusp region. A superposed epoch analysis was performed to examine causal relationship between the quantities. The occurrence of a thermospheric relative mass density anomaly, ρrel 〉1.2, in the cusp region is defining an event. The location of the density peak is taken as a reference latitude (Δ MLat = 0°). Interestingly, all the considered quantities, SSFACs, Te, and Vz are co-located with the density anomaly. The amplitudes of the peaks exhibit different characters of seasonal variation. The average relative density enhancement of the more prominent density peaks considered in this study amounts to 1.33 during all seasons. As expected, SSFACs are largest in summer with average amplitudes equal to 2.56 μA m−2, decaying to 2.00 μA m−2 in winter. The event related enhancements of Te and Vz are both largest in winter (Δ Te =730 K, Vz =136 m s−1) and smallest in summer (Δ Te = 377 K, Vz = 57 m s−1. Based on the similarity of the seasonal behaviour we suggest a close relationship between these two quantities. A correlation analysis supports a linear relation with a high coefficient greater than or equal to 0.93, irrespective of season. Our preferred explanation is that dayside reconnection fuels Joule heating of the thermosphere causing air upwelling and at the same time heating of the electron gas that pulls up ions along affected flux tubes.

Beschreibung: We document Quaternary fluvial incision driven by fault-controlled surface deformation in the inverted intermontane Gökırmak Basin in the Central Pontide mountains along the northern margin of the Central Anatolian Plateau. In-situ-produced 10Be, 21Ne, and 36Cl concentrations from gravel-covered fluvial terraces and pediment surfaces along the trunk stream of the basin (the Gökırmak River) yield model exposure ages ranging from 7 ± 1 ka to 346 ± 45 ka and average fluvial incision rates over the past ~350 ka of 0.28 ± 0.01 mm a-1. Similarities between river incision rates and coastal uplift rates at the Black Sea coast suggest that regional uplift is responsible for the river incision. Model exposure ages of deformed pediment surfaces along tributaries of the trunk stream range from 60 ± 5 ka to 110 ± 10 ka, demonstrating that the thrust faults responsible for pediment deformation were active after those times and were likely active earlier as well as explaining the topographic relief of the region. Together, our data demonstrate cumulative incision that is linked to active internal shortening and uplift of ~0.3 mm a-1 in the Central Pontide orogenic wedge, which may ultimately contribute to the lateral growth of the northern Anatolian Plateau.

Beschreibung: Plinian and Ignimbrite deposits represent explosive activity (ca. 17-19 cal ka) within the predominantly effusive and mildly explosive (Strombolian) volcanic history of Mount Etna (Italy). Proximal glasses from the Biancavilla Ignimbrites and Unit D Plinian fall deposits are characterised. Fall deposits recorded at Acireale (D1b and D2b) and Giarre (D1a and D2a) are geochemically distinct confirming they relate to different eruptions. The Acireale Plinian fall (D1b and D2b) deposits compositionally overlap with the Biancavilla Ignimbrite deposits. These explosive eruptions from Etna are considered responsible for widespread ash dispersals throughout the central Mediterranean region, producing the marker tephra layers (Y-1/Et-1) recorded in marine and lacustrine sedimentary archives. Stratigraphically these distal tephras occur at or close to the onset of the last deglaciation (Termination 1) within their respective palaeoenvironmental records, therefore making them potentially crucial tephrostratigraphic markers. This study investigates distal tephra deposits thought to be from Etna recorded in the Ionian Sea (Y-1), Lago Grande di Monticchio (LGdM, Italy; tephras TM-11 and TM-12-1), Lago di Mezzano (Italy) and the Haua Fteah cave (Libya). The glass chemistry of Y-1 tephras recorded in the Ionian Sea and at Haua Fteah are consistent with the Biancavilla Ignimbrites (16,965-17,670 cal yrs BP) and the upper Acireale Plinian fall (D2b). The LGdM record indicates that explosive activity on Etna associated with Unit D spans a minimum of 1540 ± 80 varve years. TM-12-1 (19,200-19,804 cal yrs BP) in LGdM appears to represent the oldest distal counterpart of Etna Unit D explosive activity and is associated with the lower Acireale (D1b) Plinian eruption. The proximally undefined TM-11 (17,640-18,324 cal yrs BP) and distal correlatives are geochemically distinct from the Ionian Sea Y-1 tephra. Such significant compositional differences seen between distal tephra layers are not observed within individual proximal units and are likely to indicate that the distal tephras relate to separate eruptive phases. Until proximal relationships can be established, the TM-11 type Y-1 equivalents should be termed TM-11. Great care should be exercised when using these distal ash layers to synchronise sedimentary records during a crucial period of environmental change.

Beschreibung: Earthquakes are commonly located by linearized inversion of discrete arrival time picks made from signals recorded at a network of seismic stations. If mis-picks are made, these will contribute to the location, therefore causing potential bias. For data recorded by a dense seismic array, direct imaging methods can be applied instead. We describe the ‘coalescence microseismic mapping’ method, which is a bridge between the two approaches and will operate with seismic data recorded continuously on a sparse array. By continuously mapping scalar signals derived from the envelope of seismic arrivals we derive robust estimates of the spatiotemporal coordinates of the origins of seismic events. Noisy data are migrated away from the correct origin, so do not contribute to errors in location. The method is rooted in a Bayesian formulation of event location traveltime inversion, allows imaging of source locations and has the capacity to handle errors in modelled traveltimes. It has the advantage of working with any 3-D velocity model, which thereforemay include anisotropy. It also automatically incorporates both P- and S-wave data. A multiresolution grid search leads to an efficient implementation, with a search over a larger domain including joint inversion for location and velocity structure possible where warranted by the data quality. We discuss the theory and implementation of this method and illustrate it with real data from microseismic events in Iceland caused by melt intrusion in the crust.

Beschreibung: The geological storage of CO2 in deep saline aquifers is seen as a promising measure for reducing anthropogenic greenhouse gas emissions into the atmosphere. However, generally large-scale pressure build-up as a result of CO2 injection may impact the mechanical behaviour of reservoir, caprock and existing faults. Caprock fracturing, ground uplift, reactivation of faults or induced seismicity are inherent risks that may pose potential health, security and environmental hazards.

Beschreibung: Additional keywords: co-seismische hydrogeologische Phaenomene, seismotektonisches Modell

Beschreibung: Wissenschaftliche Projekte produzieren große Mengen an Literatur in Form von Artikeln, Büchern, Buchkapiteln, Dissertationen, Diplomarbeiten. Mitunter ist das Sammeln, Auswerten, Analysieren und Anreichern mit neuen Erkenntnissen von Literatur selbst Teil des Projektauftrags. Nach Abschluss des Projekts versinken diese mit großem Aufwand zusammengetragenen wertvollen fachspezifischen Literatursammlungen häufig und geraten, etwa nach Abschalten der entsprechenden Projektwebseiten, aufgrund mangelnder technischer Ausstattung oder veralteter Datenformate, in Vergessenheit und werden somit interessierten Nachnutzern vorenthalten. Die Bibliothekssuchmaschine ALBERT, ein gemeinsames Produkt des KOBV und der Bibliothek des Wissenschaftsparks Albert Einstein, greift diesen Malus auf und macht Sammlungen von Projektliteratur dauerhaft und normiert verfügbar. So werden abgeschlossene oder auch laufende Projekte per Export in ALBERT integriert und als eigene Kollektion dargestellt. Darüber hinaus bietet ALBERT die Möglichkeit, eine eigene permanente Landing Page zu erstellen, die neben generellen Informationen zum Projekt auch als Quereinstieg für Google und Konsorten dient, wodurch ein weitaus höherer Verbreitungsgrad erzeugt wird. Der meist leicht zu realisierende XML-Export beugt zudem veralteten Datenformaten vor. Der Zugang zur Projektliteratur selbst wird dadurch wesentlich erleichtert und verstetigt. So wird offen zugängliche Literatur im Volltext indexiert und direkt über ALBERT angeboten. Andere Inhalte, die lizensiert sind oder deren Urheberschaft unklar ist, werden in der Bibliothek als gedruckte Kopie vorgehalten und können so eingesehen werden. Aus der Vielfalt der sonstigen erschlossenen Quellen sowie der angebotenen Services in ALBERT kann in Verbindung mit institutsassoziierten Projekten so ein sehr umfassendes und einzigartiges Fachportal entstehen, das sonst verstreute Kollektionen gewinnbringend zusammenführt und vor der digitalen Amnesie bewahrt.

Beschreibung: Since the International Geophysical Year (1957), a view has prevailed that East Antarctica has a relatively homogeneous lithospheric structure, consisting of a craton-like mosaic of Precambrian terranes, stable since the Pan-African orogeny 500 million years ago (e.g. Ferracioli et al. 2011). Recent recognition of a continental-scale rift system cutting the East Antarctic interior has crystallised an alternative view of much more recent geological activity with important implications. The newly defined East Antarctic Rift System (EARS) (Ferraccioli et al. 2011) appears to extend from at least the South Pole to the continental margin at the Lambert Rift, a distance of 2500 km. This is comparable in scale to the well-studied East African rift system. New analysis of RadarSat data by Golynsky & Golynsky (2009) indicates that further rift zones may form widely distributed extension zones within the continent. A pilot study (Vaughan et al. 2012), using a newly developed gravity inversion technique (Chappell & Kusznir 2008) with existing public domain satellite data, shows distinct crustal thickness provinces with overall high average thickness separated by thinner, possibly rifted, crust. Understanding the nature of crustal thickness in East Antarctica is critical because: 1) this is poorly known along the ocean–continent transition, but is necessary to improve the plate reconstruction fit between Antarctica, Australia and India in Gondwana, which will also better define how and when these continents separated; 2) lateral variation in crustal thickness can be used to test supercontinent reconstructions and assess the effects of crystalline basement architecture and mechanical properties on rifting; 3) rift zone trajectories through East Antarctica will define the geometry of zones of crustal and lithospheric thinning at plate-scale; 4) it is not clear why or when the crust of East Antarctica became so thick and elevated, but knowing this can be used to test models of Cenozoic ice sheet formation and stability. References Chappell, A.R. & Kusznir, N.J. 2008. Three-dimensional gravity inversion for Moho depth at rifted continental margins incorporating a lithosphere thermal gravity anomaly correction. Geophysical Journal International, 174 (1), 1–13. Ferraccioli, F., Finn, C.A., Jordan, T.A., Bell, R.E., Anderson, L.M. & Damaske, D. 2011. East Antarctic rifting triggers uplift of the Gamburtsev Mountains Nature, 479, 388–392. Golynsky, A.V. & Golynsky, D.A. 2009. Rifts in the tectonic structure of East Antarctica (in Russian). Russian Earth Science Research in Antarctica, 2, 132–162. Vaughan, A.P.M., Kusznir, N.J., Ferraccioli, F. & Jordan, T.A.R.M. 2012. Regional heat-[U+FB02]ow prediction for Antarctica using gravity inversion mapping of crustal thickness and lithosphere thinning. Geophysical Research Abstracts, 14, EGU2012–8095.

Beschreibung: The study of mantle lithosphere plays a key role to reveal predominant tectonic setting process of a region. The current geological and tectonic setting of Iran is due to the ongoing continental–continental collision of the Arabian and Eurasian plates. We applied a combined P and S receiver function analysis to the teleseismic data of nine permanent broadband seismic stations of the International Institute of Earthquake Engineering and Seismology located in different tectonic zones of Iranian plateau. More than 4 years of data were used to estimate the thickness of the crust and mantle lithosphere. According to our results, the crust is 50 km thick beneath the Zagros fold and thrust belt (ZFTB). We found the maximum Moho depth of approximately 70 km under the Sanandaj-Sirjan zone (SSZ) indicating the overthrusting of the crust of Central Iran onto the Zagros crust along the main Zagros thrust (MZT). Below the northeasternmost part of the Urumieh–Dokhtar Magmatic Arc (UDMA) and Central Iran, the Moho becomes shallower and lies at 40 km depth. Towards northeast, beneath the Alborz zone, the crust is 55 km thick. Based on S receiver functions, we provided new insights into the thickness of the Arabian and Eurasian lithospheres. The location of the boundary between these plates was estimated to be beneath the SSZ, which is slightly shifted northeastward relative to the surficial expression of the MZT. Furthermore, the Arabian plate is characterized by the relatively thick lithosphere of about 130 km beneath the ZFTB reaching 150 km beneath the SSZ, where the thickest crust was also observed. This may imply that the shortening across the Zagros is accommodated by lithospheric thickening. In contrast, UDMA and Central Iran are recognized by the thin lithosphere of about 80– 85 km. This thin lithosphere may be associated with the asthenospheric upwelling caused by either lithospheric delamination or Neo-Tethys slab detachment beneath the Zagros collision zone.

Beschreibung: The large scale storage of energy is a great challenge arising from the planned transition from nuclear and CO2-emitting power generation to renewable energy production, by e.g. wind, solar, and biomass in Germany. The most promising option for storing large volumes of excess energy produced by such renewable sources is the usage of underground porous rock formations as energy reservoirs. Some new technologies are able to convert large amounts of electrical energy into a chemical form, for example into hydrogen by means of water electrolysis. Porous formations can potentially provide very high hydrogen storage capacities. Several methods have to be studied including high hydrogen diffusivity, the potential reactions of injected hydrogen, formation fluids, rock composition, and the storage complex. Therefore, in August 2012 the collaborative project H2STORE ("hydrogen to store") started to investigate the feasibility of using burial clastic sediments of depleted gas reservoirs as well as recently used gas storage sites as potential hydrogen storage media. In Germany, such geological structures occur at various geographic sites and different geological strata. These deposits are characterized by different geological-tectonic evolution and mineralogical composition, mainly depending on palaeogeographic position and diagenetic burial evolution. Resulting specific sedimentary structures and mineral parageneses will strongly control formation fluid pathways and associated fluid-rock/mineral reactions. Accordingly, H2STORE will analyze sedimentological, petrophysical, mineralogical/geochemical, hydrochemical, and microbiological features of the different geological strata and the German locations to evaluate potential fluid-rock reactions induced by hydrogen injection. Such potential reactions will be experimentally induced in laboratory runs, as analogues for naturally occurring processes in deep seated reservoirs. Finally, rock data determined before and after these experiments will be used as major input parameters for numerical modelling of mineralogical and microbiological reactions. Such reactions are expected to have a strong affect on rock porosity-permeability evolution and therefore the characteristics of flow processes in reservoir and the barrier properties of sealing rocks. The special topic of this study will be the modelling of hydrogen propagation in the subsurface reservoir formation supplemented by its mixing with the residual gases as well as the simulation of coupled bio-dynamic processes and of reactive transport in porous media. These numerical simulations will enable the transfer of experimental results from the laboratory runs to the field-scale and the formulation of the requirements for hydrogen storage in converted gas fields. Thus, the major objectives of H2STORE are to obtain fundamental data on the behaviour of clastic sediments in the presence of formation fluids and injected hydrogen, its impact on petrophysical features and the development of the most realistic modelling for proposed and experimentally induced rock alteration as well as complex gas mixing processes in potential geological hydrogen reservoirs. Moreover these results will be used when discussing the possibility of "green" eco-methane generation by hydrogen and carbon dioxide interaction in the geological underground.

Beschreibung: Porosity and permeability of reservoirs are key parameters for an economical use of hydrogeothermal energy. Both may be significantly reduced by precipitation of minerals. The Allermöhe borehole near Hamburg (Germany) represents a case in which precipitation of anhydrite resulted in a failed reservoir development. We introduce a new numerical approach for better understanding of this, considering both the spatial variations of supersaturation on the pore scale and the pore space structure. Besides pore size this requires consideration of the effects of surface charge density on the fluid supersaturation in porous media and of the role of fluid flow velocity.

Beschreibung: In order to characterize the chemical reactivity and hence the mineralogical CO2 sequestration potential of carbonate minerals, laboratory fluidsiderite/ankerite CO2 exposure experiments have been performed. Experiments were conducted on a hydrothermal rocking autoclave system equipped with flexible Titanium cells allowing for isobaric and isothermal fluid sampling. Crushed siderite/ankerite separates have grain sizes between 100 and 200 μm. The minerals were reacted together with pure CO2 and 2 M NaCl brine at 80 °C and 20 or 30 MPa, respectively; run durations were one week. Approximately 120 ml NaCl brine and 5.5 g of powdered carbonate separate were filled into the Titanium cells to yield a brine to mineral weightratio of 20 to 1. Experiments were supersaturated with CO2 during entire run durations. Successive fluid samples were taken after several different time steps to determine time dependent dissolution behavior. Solid samples were recovered upon completion of each run and analyzed by XRD as well as SEM. Fluid sample compositions were determined by ICPAES.

Beschreibung: Angular momentum forecasts for up to 10 days into the future, modeled from predicted states of the atmosphere, ocean and continental hydrosphere, are combined with the operational IERS EOP prediction bulletin A to reduce the prediction error in the very first day and to improve the subsequent 90-day prediction by exploitation of the revised initial state and trend information. EAM functions derived from ECMWF short-range forecasts and corresponding LSDM and OMCT simulations can account for high-frequency mass variations within the geophysical fluids for up to 7 days into the future primarily limited by the accuracy of the forecasted atmospheric wind fields. Including these wide-band stochastic signals into the first days of the 90-day statistical IERS predictions reduces the mean absolute prediction error even for predictions beyond day 10, especially for polar motion, where the presently used prediction approach does not include geophysical fluids data directly. In a hindcast experiment using 1 year of daily predictions from May 2011 till July 2012, the mean prediction error in polar motion, compared to bulletin A, is reduced by 32, 12, and 3 % for prediction days 10, 30, and 90, respectively. In average, the prediction error for medium-range forecasts (30–90 days) is reduced by 1.3–1.7 mas. Even for UT1-UTC, where AAM forecasts are already included in IERS bulletin A, we obtain slight improvements of up to 5 % (up to 0.5 ms) after day 10 due to the additional consideration of oceanic angular momentum forecasts. The improved 90-day predictions can be generated operationally on a daily basis directly after the publication of the related IERS bulletin A product finals2000A.daily.

Beschreibung: Numerous monitoring applications make use of seismic coda waves to evaluate velocity changes in the Earth. This raises the question of the spatial sensitivity of coda wave-based measurements. Here, we investigate the depth sensitivity of coda waves to local velocity perturbations using 2-D numerical wavefield simulations. We calculate the impulse response at the surface before and after a slight perturbation of the velocity within a thin layer at depth is introduced. We perform a parametric analysis of the observed apparent relative velocity changes, εobs, versus the depth of the thin perturbed layer. Through the analysis of the decay of εobs, we can discriminate two different regimes: one for a shallow perturbation and the other for a deep perturbation. We interpret the first regime as the footprint of the 1-D depth sensitivity of the fundamental surface wave mode. To interpret the second regime, we need to model the sensitivity of the multiply scattered body waves in the bulk. We show that the depth sensitivity of coda waves can be modelled as a combination of bulk wave sensitivity and surface wave sensitivity. The transition between these two regimes is governed by mode conversions due to scattering. We indicate the importance of surface waves for the sensitivity of coda waves at shallow depths and at early times in the coda. At later times, bulk waves clearly dominate the depth sensitivity and offer the possibility of monitoring changes at depths below the sensitivity of the surface waves. Based on the transition between the two regimes, we can discriminate a change that occurs at the surface from a change that occurs at depth. This is illustrated for shallow depth perturbations through an example from lunar data.

Beschreibung: The paleogeography of the Altaids and its kinematic and tectonic evolution during the final collision and amalgamation of Eurasia is still poorly known. Addressing this problem, a paleomagnetic study has been undertaken on Paleozoic sedimentary rocks from the Karatau, Southern Kazakhstan. Stepwise thermal demagnetization reveals the presence of a high-temperature component of magnetization in most samples. Fold tests indicate a syn-folding age of magnetic remanence acquisition at three of the five areas studied. Directional data of Devonian and Permian rocks yield a positive fold test, implying a primary magnetization. Resulting prefolding paleolatitudes for Permian and Devonian rocks show the proximity of the Karatau to Baltica during those times. Syn- and post-folding magnetizations result in paleolatitudes for Karatau, which intersect the paleolatitude curve based on the Baltica apparent polar wander path (APWP), at times, which can be correlated to major deformational events at ~280 Ma, ~260 Ma, and ~230 Ma, respectively. We interpret this with complicated pattern of remagnetization events accompanying deformation, which can include syn-folding remagnetization events and areas of primary magnetic signals. Additionally, the differences between reference declinations based on the APWP for Baltica and observed declinations suggest successive counterclockwise rotational reorganization of the Karatau during the late Paleozoic to Early Mesozoic, with maximal rotation values of ~65° with respect to Baltica. The remagnetization events are correlated with latest intracontinental stages of orogenic evolution in the Ural mountains and thus the Paleozoic amalgamation of the Eurasian continent and suggest synchronous and coherent tectonic evolution in the Urals and Karatau mountains.

Beschreibung: On February 27, 2010, the Central Chilean margin ruptured over a length of _400 km in the Mw 8.8 Maule earthquake. The international seismological community responded quickly by organising the International Maule Aftershock Deployment (IMAD) consisting of more than 140 seismological stations from Chile, Germany, France, the USA and the UK. This land seismic network is complemented by 30 ocean bottom seismometers in the northern portion of the rupture, operating from September to December 2012. Similar efforts were carried out by the geodetic community, installing more than 65 cGPS stations and an even larger number of campaign sites. Last but not least surveys of coastal uplift and surface faulting provide constraints on the immediate coseismic response as well as on the longer term evolution of the margin. In the MARISCOS project (MAule eaRthquake: Integration of Seismic Cycle Observations and Structural investigations) seismological, geodetic and geological approaches are combined in order to link coseismic slip, the postseismic response, and the longer term properties of the margin. We have created a bulletin of over 16000 events with low epicentral uncertainties. Seismic activity occurs in 4 main groups: (1) Normal faulting outer rise events at depths between the surface and 30 km depth. (2) a dipping 70-80 wide band along the whole rupture zone, thin in cross-section. Most of the events in this band are consistent with plate interface seismicity, but a kink in cross-section suggests the existence of a splay fault forming the shallowest part. This band is separated from the trench by a 50 km aseismic zone and is approximately terminated by the coastline on the landward side (at least to the north of the main shock epicentre), likely corresponding to the plate interface-continental Moho intersection at depth. (3) elongated clusters of seismicity at 40-50 km depth and with plate interface focal mechanisms, which occur below the continental Moho. (4) Pronounced crustal seismicity, most prominently normal faulting seismicity with strike oblique to the trench occur at the northern limit of the rupture zone. The northern part of the rupture zone is imaged with local earthquake tomography and shows elevated vp/vs values (_1.85) in the western part of the intense crustal seismicity. Further seismicity occurs at intermediate depth range (80-120 km) and shallowly in the volcanic arc. Improved models of coseismic and postseismic slip were computed based on the high density geodetic data and with a realistic plate geometry and elasticity structure. The postseismic response over the first 420 days is characterised by elongated patches of afterslip downdip of the coseismic slip in the rupture zone north of the hypocentre, which spatially largely coincides with the main plate interface seismicity (group 2). The equivalent moment of the afterslip is much larger than the cumulative seismic moment of the aftershocks, but although there is a close temporal correspondence in the decay of afterslip and seismicity, the slip of some aftershocks might be larger than the cumulative afterslip. A deeper patch of afterslip to the south of the coseismic slip is not associated with significant seismicity. Based on the detailed aftershock locations, we have implemented dynamic station corrections for backprojection of the main shock using stations in the US, Antarctica, and Africa. Using this calibration we are able to image coherent energy at frequencies above 2-4 Hz. Similar to other investigators we find that higher frequency energy release is found downdip of the lower frequency release and geodetic slip, but contrary to some published work we locate the HF release for the northern part of this rupture near the downdip end of the main aftershock zone (group 2), updip of the deep band (group 3) for rupture times 〉 50 s. Before 50 s, we find rupture further downdip nearer group 3 seismicity at the deepest part of seismogenic plate interface. Taken together, these results indicate that rather than being either velocity weakening (unstable, Seismogenic) or velocity strengthening (stable, creeping), the plate interface over large areas can switch between both modes of frictional behaviour and is maybe over large areas in a conditionally stable regime, where fluid diffusion can control the variable behaviour.

Beschreibung: Upward brine migration along a potentially open fault as a result of underground utilization could endanger freshwater-bearing horizons. The present study aimed the investigation of pressure elevation and brine displacement for a prospective storage located in the Northeast German Basin using multi-phase flow simulations.

Beschreibung: The Greenland and Antarctic ice sheets have been reported to be losing mass at accelerating rates1, 2. If sustained, this accelerating mass loss will result in a global mean sea-level rise by the year 2100 that is approximately 43 cm greater than if a linear trend is assumed2. However, at present there is no scientific consensus on whether these reported accelerations result from variability inherent to the ice-sheet–climate system, or reflect long-term changes and thus permit extrapolation to the future3. Here we compare mass loss trends and accelerations in satellite data collected between January 2003 and September 2012 from the Gravity Recovery and Climate Experiment to long-term mass balance time series from a regional surface mass balance model forced by re-analysis data. We find that the record length of spaceborne gravity observations is too short at present to meaningfully separate long-term accelerations from short-term ice sheet variability. We also find that the detection threshold of mass loss acceleration depends on record length: to detect an acceleration at an accuracy within ±10 Gt yr−2, a period of 10 years or more of observations is required for Antarctica and about 20 years for Greenland. Therefore, climate variability adds uncertainty to extrapolations of future mass loss and sea-level rise, underscoring the need for continuous long-term satellite monitoring.

Beschreibung: The Modular Opto-electronic Multispectral Stereo Scanner MOMS-02 experimental data acquired during the German Spacelab D2 mission will be used for a broad range of geoscientific objectives. The simultaneous acquisition of high spatial resolution, multispectral and stereo scenic data enables a real combination of thematic and topographic information, thus considerably improving the verification and interpretation of dynamic changes of the Earth"s surface by means of remote sensing. This paper gives a first assessment of the MOMS-02/D2 mission, the data quality and an overview on the planned methodological and application-oriented investigations for various test sites. On the basis of a few examples the possibilities of this system for future thematic applications is shown.