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In this article, a high-resolution acoustic emission sensor, accelerometer and broadband seismometer array data set is made available and described in detail from in-situ experiments performed at Äspö Hard Rock Laboratory in May and June 2015. The main goal of the hydraulic stimulation tests in a horizontal borehole at 410 m depth in naturally fractured granitic rock mass is to demonstrate the technical feasibility to generate multi-stage heat exchangers in a controlled way superior to former massive stimulations applied in enhanced geothermal projects. A set of six, sub-parallel hydraulic fractures is propagated from an injection borehole drilled parallel to minimum horizontal in-situ stress, and monitored by an extensive complementary sensor array implemented in three inclined monitoring boreholes and the near-by tunnel system. Three different fluid-injection protocols are tested: constant water injection, progressive cyclic injection, and cyclic injection with a hydraulic hammer operating at 5 Hz frequency to stimulate a crystalline rock volume of size 30 x 30 x 30 m at depth. We collected geological data from core and borehole logs, fracture inspection data from impression packer, acoustic emission hypocenter tracking and tilt data, as well as quantified the permeability enhancement process. The data and interpretation provided through this publication is an important step both, in upscaling laboratory tests, and downscaling field tests in granitic rock in the framework of enhanced geothermal system research.

The GFZ organizes annually International Training Courses on “Seismology, Seismic Data Analysis, Hazard Assessment and Risk Mitigation”. They provide theoretical fundamentals and practical training for geo-scientists and engineers from countries in Asia, Africa, and Latin America. The courses are being supported by the German Federal Foreign Office and are a contribution to the global UN Sendai Framework for Disaster Risk Reduction (UNDRR).In line with the growing demand by participants in former courses for mainly practice-oriented training and workshop discussions related to case studies, the course program comprises, besides introductory and state-of-the-art review lectures on the various subjects of earthquake seismology and risk assessment, extensive practical exercises, demonstrations, workshop discussions and scientific excursions. Generally, the course program aims at developing interdisciplinary problem understanding, acquaintance with the theoretical fundamentals and basic features of modern instrumentation, commonly used models and algorithms as well as developing practical skills in data evaluation and analysis. The courses are being announced through the GFZ website, the EMSC, and IRIS as well as printed information. Additional ad-hoc sponsors are mainly from the hosting institutions and governments in case of regional courses in Asia, Africa, or Latin America.Since 1992 these 4-week courses are held alternately as world-wide open courses in Potsdam or as regional courses in earthquake-prone countries in Asia, Africa, or Latin America (2006 Kyrgyzstan, 2008 Costa Rica, 2010 Turkey, 2012 Morocco, 2014 Colombia, 2016 Myanmar, and 2018 Ghana). Many of the former course participants became project partner in ongoing research projects of German and European institutions., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

Induced seismicity is one of the main factors that reduces societal acceptance of deep geothermal energy exploitation activities, and felt earthquakes are the main reason for closure of geothermal projects. Implementing innovative tools for real-time monitoring and forecasting of induced seismicity was one of the aims of the recently completed COSEISMIQ project. Within this project, a temporary seismic network was deployed in the Hengill geothermal region in Iceland, the location of the nation's two largest geothermal power plants. In this paper, we release raw continuous seismic waveforms and seismicity catalogues collected and prepared during this project. This dataset is particularly valuable since a very dense network was deployed in a seismically active region where thousand of earthquakes occur every year. For this reason, the collected dataset can be used across a broad range of research topics in seismology ranging from the development and testing of new data analysis methods to induced seismicity and seismotectonics studies., Scientific Data, 9, ISSN:2052-4463

Induced seismicity is one of the main factors that reduces societal acceptance of deep geothermal energy exploitation activities, and felt earthquakes are the main reason for closure of geothermal projects. Implementing innovative tools for real-time monitoring and forecasting of induced seismicity was one of the aims of the recently completed COSEISMIQ project. Within this project, a temporary seismic network was deployed in the Hengill geothermal region in Iceland, the location of the nation’s two largest geothermal power plants. In this paper, we release raw continuous seismic waveforms and seismicity catalogues collected and prepared during this project. This dataset is particularly valuable since a very dense network was deployed in a seismically active region where thousand of earthquakes occur every year. For this reason, the collected dataset can be used across a broad range of research topics in seismology ranging from the development and testing of new data analysis methods to induced seismicity and seismotectonics studies.

Seismic swarms close to volcanoes often signal the onset of unrest. Establishing whether magma is the culprit and the unrest can be flagged as magmatic may be challenging. Here we analyze the spatio-temporal pattern of a seismic swarm that occurred in November 2015–February 2016 around Jailolo volcano, a long-dormant and poorly studied volcano located on Halmahera island, North Moluccas, Indonesia. The swarm included four Mw > 5 earthquakes and hundreds of events were felt by the population. We relocate the earthquakes using both the Indonesian Seismic Network and single-station location techniques. We find that the earthquakes cluster in a narrow strip, stretching 5 km E–W and 20 km N–S, migrating southward away from Jailolo volcano at ~10 km/d. We investigate the source mechanisms of the largest earthquakes via full moment tensor inversion. The non-double-couple component is around 50%, such that the earthquakes, besides normal faulting, included a relatively large opening component. After a thorough examination of the possible causes of the Jailolo swarm we conclude that a laterally propagating dike of tens of millions of cubic meters is the triggering mechanism for the seismicity. The swarm marks the first documented magmatic unrest at Jailolo. We find that there is a probability >0.1 that the unrest will last for more than 2 years. This magmatic unrest calls for the classification of Jailolo volcano as active, and for an urgent assessment of the associated volcanic hazard.

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 networks dealt 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., System Erde; 3

System Erde; 1, The tsunami of 26 December 2004 in the Indian Ocean, generated by an earthquake with a magnitude of 9.3 offshore Northern Sumatra, caused one of the largest natural disasters in history. As a reaction to this devastating catastrophe a Tsunami Early Warning System is being developed and installed in the region since 2005. This article describes the causes of a tsunami, and explains the concept, technical components and functionality of the Early Warning System.

Megacities as challenge for interdisciplinary research: the "Risk Habitat Megacity" research initiative / Dirk Heinrichs, Kerstin Krellenberg. - Mega-urban societies at risk / Frauke Kraas, Carsten Butsch. - Megacity Istanbul: earthquake risk and early warning in a megacity / Stefano Parolai, Jochen Zschau, Claus Milkereit, Matteo Picozzi, Angelo Strollo. - Neapel in der Zange / Thomas Walter

The rapid increase in energy demand in the city of Reykjavik has posed the need for an additional supply of deep geothermal energy. The deep-hydraulic (re-)stimulation of well RV-43 on the peninsula of Geldinganes (north of Reykjavik) is an essential component of the plan implemented by Reykjavik Energy to meet this energy target. Hydraulic stimulation is often associated with fluid-induced seismicity, most of which is not felt on the surface but which, in rare cases, can be a nuisance to the population and even damage the nearby building stock. This study presents a first-of-its-kind pre-drilling probabilistic induced seismic hazard and risk analysis for the site of interest. Specifically, we provide probabilistic estimates of peak ground acceleration, European microseismicity intensity, probability of light damage (damage risk), and individual risk. The results of the risk assessment indicate that the individual risk within a radius of 2 km around the injection point is below 0.1 micromorts, and damage risk is below 10−2, for the total duration of the project. However, these results are affected by several orders of magnitude of variability due to the deep uncertainties present at all levels of the analysis, indicating a critical need in updating this risk assessment with in situ data collected during the stimulation. Therefore, it is important to stress that this a priori study represents a baseline model and starting point to be updated and refined after the start of the project., Natural Hazards and Earth System Sciences, 20 (6), ISSN:1561-8633, ISSN:1684-9981