ALBERT

Description: Central Asia was identified as one of the regions of the world with the highest seismic hazard and risk. However, the actual lack and heterogeneity of available seismological and vulnerability data make any possible seismic risk scenario highly uncertain. In order to improve seismic risk assessment in Central Asia efforts must be carried out to both increase the seismological knowledge in the area and to update and harmonise the existing vulnerability data set in the different countries. To this regard, within the Central Asia Cross-Border Natural Disaster Prevention (CASCADE) project, financed by the German Federal Foreign Office, a cross-border seismological and strong motion network in Central Asia (CAREMON) was installed. Microzonation studies in the capitals of Kyrgyzstan and Uzbekistan were started, and those for Kazakhstan, Tajikistan and Turkmenistan were triggered. The collection of a harmonised (in terms of the European Macroseismic Scale EMS) building vulnerability data base was also achieved, and a capacity building and training program accompanied all the different tasks of the project. All these activities were carried out within the framework of, and supported by, the Global Change Observatory Central Asia (GCO-CA). The digital data collected by the CAREMON network will allow to improve localisation of the seismicity in the area and to improve completeness of earthquake catalogues necessary for sounded seismic hazard assessment at regional scale. The results of the microzonation will be exploited for improving the seismic hazard and risk assessment in the capitals. Attempts were already carried out for Bishkek. Follow-up activities, including the establishment of a vertical array of accelerometer in Bishkek, are foreseen for further improving seismic hazard and risk analysis in Central Asia.

Description: Glaciers play an important role in the water cycle of many regions of the world, especially in dry regions such as Central Asia. Glaciers can store water over decades and transfer winter precipitation into the summer months by releasing the accumulated snow and ice as melt water. The question about the state of the glaciers within a region is therefore intrinsically linked to questions about water availability and food security. We assess the current state of all glaciers of the Tien Shan (the main mountain range in Central Asia, feeding its waters to Kyrgyzstan, Kazakhstan, Uzbekistan and China) by three different groups of methods. We considered measurements of the Earth’s gravity field, laser altimetry, and direct glaciological measurements, and assessed uncertainties in an ensemble-like approach. The results of all three methods agree well, increasing the confidence in the final estimate. The results indicate that during the period 2003-2009, the glaciers of the Tien Shan were losing mass at a rate of 7.1 ±5.6 gigatons per year. Cumulated over the period, this corresponds to the water volume stored in Lake Constance (Bodensee).

Description: Central Asia belongs to the regions of the world most exposed to high levels of seismic hazard. After the collapse of Soviet Union, the seismic monitoring in this area decreased significantly in quality and quantity since the maintenance of previous analog networksdealt with serious economic difficulties. Moreover, the installation of modern digital network was limited to few cases (e.g. stations in Kazakhstan or the KNET deployed in Kyrgyzstan). In the last decade the situation improved but still the new networks are concentrated in a few regions and devoted mainly to weak-motion seismology. In this article, we describe the installation of a small strong-motion network in the Kyrgyz capital Bishkek, intended for earthquake early warning and rapid response purposes. Low cost strong-motion stations developed at GFZ have been installed in seven buildings spread over the town, each one monitored by several sensing units to accomplish also the task of structural health monitoring. The stations communicate via wireless link and the streams collected by one specific station are communicated to the data management center via internet. Each unit has computational power, allowing for decentralized operations related to on-site early warning. An extension of this network to a regional early warning network for real time risk assessment is expected in the near future.

Description: Earthquake hazard assessment with respect to megacities is one of the key challenges in Geosciences. Istanbul is one of these cities due to its location about 15 km north of a major tectonic plate boundary that separates the Eurasian plate from the Anatolian plate. Whereas the possible magnitude range and location of expected earthquakes can be determined with computer simulations, the precise timing in advance is not possible. Nevertheless, computer simulations of earthquake scenarios are an important tool that represents the deterministic seismic hazard assessment. Currently our research focuses on the quantification of model parameter uncertainties by means of assessing the results of earthquake-scenario simulation with statistical methods of probabilistic seismic hazard assessment. The on-going rapid increase in computing power will, in the future, enable us to simulate multiple ensembles of earthquake scenarios as done in meteorological weather forecasts in order to assess which of the simulated scenarios is the most probable to occur. The key mathematical tools in this type of modelling are numerical methods that solve the partial differential equations that describe the equilibrium of forces for the earthquake nucleation and time-dependent statistical methods that quantify the uncertainties of the models. For Istanbul this research is essential since the tectonic fault has not ruptured since 1766. The fault is mature and has the potential to produce an earthquake of Mw 〉 7.

Description: Probabilistic seismic hazard assessments (PSHA) represent one of the most practice-oriented products seismology can offer to society. As seismic load information, results of PSHA build the basis for earthquake-resistant building codes and safety proofs. They form the decisive input for seismic risk assessments and are, with this, of importance for the insurance industry. Thereby, PSHAs contribute directly to the reduction of earthquake risk, since the earthquake-resistant design of buildings represents the only sustainable protection against this kind of natural hazards. This contribution provides in a compressed form a view into the methodical basis of PSHA. In the focus are here mathematical models, which enable the generation of PSHA with quantified uncertainties on the basis of geophysical and geological data. Typical results of a PSHA are presented in form of seismic hazard curves, seismic hazard maps and response spectra for the national code DIN19700 for safety proofs of hydraulic constructions like, e.g., dams of water reservoirs (Grünthal, 2008; Grünthal et al., 2009b).

Description: Over the past two decades, our concept about the distribution of life on Earth has fundamentally changed. Microorganisms (bacteria and archaea) colonize not only the upper soil layers, but the underlying sediments and rocks as well. Previous estimates assumed that up to 94 % of all microorganisms live in deep subsurface sediments, but recent findings show that microbial abundance in the marine subsurface is much lower than previously estimated. However, these deeply buried communities are as important as the surface biosphere for driving carbon and nutrient cycling and catalyzing a multitude of reactions between rocks, sediments, and fluids. Due to their low abundance and low metabolic rates, studies of deep biosphere microorganisms require special analytical procedures. Therefore we developed an integrated research strategy, which connects geochemical measurements of sediment properties with microbiological/molecular biological analyses of microbial communities and modeling of microbial pathways/ networks. Our ongoing studies in sediments of the El’gygytgyn Crater Lake and of the South Pacific Gyre show the importance of microorganisms for the element cycles in these extreme environments. The composition of microbial communities, their role in major biogeochemical cycles and their response to changing environmental conditions, however, are still largely unknown. The future research of the German Centre for Geosciences GFZ will extend our knowledge on the role of microorganisms mainly in continental deposits, especially their impact on biogeochemical cycles, mineral weathering as well as on the quality and stability of reservoirs in the broadest sense.

Description: The Bushveld Complex in South Africa is the world’s largest magmatic intrusion and at the same time the most important source of technologically important metals including chromium, vanadium and above all the platinum group elements. This flat, saucer-shaped intrusion has a volume of about 1 million km3 and by itself classifies as a Large Igneous Province. Within this vast intrusion, the platinum ores are mined from just two thin layers: the Merensky Reef and the UG2. Each of these is about one meter thick and both are continuous over hundreds of kilometers. The ore-bearing horizons, like other layers in the complex, clearly formed by igneous processes of crystallization in a magma chamber. The reseach challenges are to understand what processes accomplished the thousand-fold concentration of platinum from background levels to ore grade, and how ores were concentrated in such thin layers in a 9 kilometer-thick intrusion. Apart from providing answers to these scientific questions, the detailed mineralogical and microchemical studies of Bushveld ores at the GFZ are also being applied to find ways of improving the efficiency of ore beneficiation and platinum recovery.