Marco Bohnhoff

Helmholtz Centre Potsdam - GFZ German Research Centre for Geosciences

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Georg Dresen

Helmholtz Centre Potsdam - GFZ German Research Centre for Geosciences

Patricia Martínez‐Garzón

Helmholtz Centre Potsdam - GFZ German Research Centre for Geosciences

Grzegorz Kwiatek

Helmholtz Centre Potsdam - GFZ German Research Centre for Geosciences

Fatih Bulut

Kandilli Observatory and Earthquake Research Institute

Yehuda Ben‐Zion

Southern California University for Professional Studies

Murat Nurlu

P. E. Malin

Applied Spectral Imaging (United States)

Mustafa Aktar

Kandilli Observatory and Earthquake Research Institute

Dirk Becker

Praxis

Recai Feyiz Kartal

Prime Minister's Office

Cooperative Institutions

Helmholtz Centre Potsdam - GFZ German Research Centre for Geosciences

133

University of Potsdam

Centre National de la Recherche Scientifique

John Wiley & Sons (United States)

Hanover College

Istituto Nazionale di Geofisica e Vulcanologia

Freie Universität Berlin

Ruhr University Bochum

Stanford University

United States Geological Survey

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Low-frequency tremor-like episodes before the 2023 MW 7.8 Türkiye earthquake linked to cement quarrying

Scientific Reports (2025)

Zahra Zali Patricia Martínez‐Garzón Grzegorz Kwiatek Sebastián Núñez-Jara Gregory C. Beroza

Spectrogram

Plucking

10.1038/s41598-025-88381-x

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Laboratory Study on Fluid‐Induced Fault Slip Behavior: The Role of Fluid Pressurization Rate

Geophysical Research Letters (2020)

Lei Wang Grzegorz Kwiatek E. Rybacki Audrey Bonnelye Marco Bohnhoff

Abstract Understanding the physical mechanisms governing fluid‐induced fault slip is important for improved mitigation of seismic risks associated with large‐scale fluid injection. We conducted fluid‐induced fault slip experiments in the laboratory on critically stressed saw‐cut sandstone samples with high permeability using different fluid pressurization rates. Our experimental results demonstrate that fault slip behavior is governed by fluid pressurization rate rather than injection pressure. Slow stick‐slip episodes (peak slip velocity < 4 μm/s) are induced by fast fluid injection rate, whereas fault creep with slip velocity < 0.4 μm/s mainly occurs in response to slow fluid injection rate. Fluid‐induced fault slip may remain mechanically stable for loading stiffness larger than fault stiffness. Independent of fault slip mode, we observed dynamic frictional weakening of the artificial fault at elevated pore pressure. Our observations highlight that varying fluid injection rates may assist in reducing potential seismic hazards of field‐scale fluid injection projects.

Cabin pressurization

Fluid pressure

10.1029/2019gl086627

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Citations (107)

Moment tensors of waste-water disposal induced seismicity in Southern Kansas.

AGU Fall Meeting Abstracts (2019)

Amandine Amemoutou Patricia Martínez‐Garzón Grzegorz Kwiatek J. L. Rubinstein Marco Bohnhoff

waste disposal

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Fault-Zone Maturity Defines Maximum Earthquake Magnitude: The case of the North Anatolian Fault Zone

EGU General Assembly Conference Abstracts (2015)

Marco Bohnhoff Fatih Bulut Eva Stierle Patricia Martínez‐Garzón Yehuda Ben‐Zion

North Anatolian Fault

Earthquake magnitude

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Slow strain release along the eastern Marmara seismic gap offshore Istanbul in conjunction with enhanced local seismic moment release

AGU Fall Meeting Abstracts (2018)

Patricia Martínez‐Garzón Marco Bohnhoff D. Mencin Grzegorz Kwiatek Georg Dresen

Conjunction (astronomy)

Strain (injury)

Seismic moment

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Insights Into Complex Subdecimeter Fracturing Processes Occurring During a Water Injection Experiment at Depth in Äspö Hard Rock Laboratory, Sweden

Journal of Geophysical Research Solid Earth (2018)

Grzegorz Kwiatek Patricia Martínez‐Garzón Katrin Plenkers Maria Leonhardt Arno Zang

Abstract We investigate the source characteristics of picoseismicity ( M w < −2) recorded during a hydraulic fracturing in situ experiment performed in the underground Äspö Hard Rock Laboratory, Sweden. The experiment consisted of six stimulations driven by three different water injection schemes and was performed inside a 28‐m‐long, horizontal borehole located at 410‐m depth. The fracturing processes were monitored with a variety of seismic networks including broadband seismometers, geophones, high‐frequency accelerometers, and acoustic emission sensors thereby covering a wide frequency band between 0.01 and 100,000 Hz. Here we study the high‐frequency signals with dominant frequencies exceeding 1000 Hz. The combined seismic network allowed for detection and detailed analysis of 196 small‐scale seismic events with moment magnitudes M W < −3.5 (source sizes of decimeter scale) that occurred solely during the stimulations and shortly after. The double‐difference relocated hypocenter catalog as well as source parameters were used to study the physical characteristics of the induced seismicity and then compared to the stimulation parameters. We observe a spatiotemporal migration of the picoseismic events away and toward the injection intervals in direct correlation with changes in the hydraulic energy (product of fluid injection pressure and injection rate). We find that the total radiated seismic energy is extremely low with respect to the product of injected fluid volume and pressure (hydraulic energy). The radiated seismic energy correlates well with the hydraulic energy rate. The obtained fault plane solutions for particularly well‐characterized events signify the reactivation of preexisting rock defects under influence of increased pore fluid pressure on fault plane orientations in good correspondence with the local stress field orientation.

Geophone

Seismometer

Passive seismic

Hypocenter

Seismic moment

Microseism

10.1029/2017jb014715

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Coda Q analysis of active UT measurements to monitor the dm-scale fracture network in response to the STIMTEC hydraulic stimulations, Reiche Zeche URL (Germany)

Aglaja Blanke Carolin Boese Georg Dresen Marco Bohnhoff Grzegorz Kwiatek

The occurrence of induced microseismicity is commonly used to characterize a stimulated geo-reservoir, e.g. in terms of monitoring the damage and stress evolution in the rock mass. Studies in Underground Research Laboratories (URLs) have the advantage that a close by Acoustic Emission monitoring system (earthquake source – receiver distances < 50 meters) allows to investigate the detailed evolution of induced seismicity at the decimeter scale in response to injection operations. Controlled hydraulic stimulation experiments often benefit from additional active seismic measurements conducted near the source regions of the induced seismic events to better characterize the rock mass. The so-called active Ultrasonic Transmission (UT) measurements produce stronger signals covering a broad frequency range from the centimeter to decimeter scale which may be used to investigate space-time varying fracture network development and attenuation properties. The STIMTEC project in the Reiche Zeche URL in Freiberg (Germany) provides more than 300 active UT measurements that were performed before and after hydraulic stimulations in two boreholes in the targeted rock volume, an anisotropic metamorphic gneiss. To investigate spatio-temporal changes of frequency-dependent scattering attenuation and thus to monitor variations in the local fracture network, we analyzed S-coda waves of 88 spatially representative UT measurements covering a signal frequency content of 1 – 60 kHz. We grouped neighboring UT measurements to estimate frequency-dependent mean-Qc (coda quality factor) values for in total eight UT groups, covering different borehole depth intervals and time periods. Stable Qc estimates for center frequencies between 3 – 21 kHz of octave-width frequency bands were obtained. Our estimates show a characteristic frequency-dependence as observed at the field scale in geological reservoirs. Temporal variations of Qc values are strongly connected to hydraulic stimulation, and these variations are more significant than those resolved from estimated velocity changes. We find indication for healing processes of injection-induced small-scale fractures during a two-months post-stimulation phase indicated by attenuation changes at high frequencies not resolvable at the earth’s surface. The coda analysis further reveals spatial differences of attenuation characteristics supporting previous assumptions based on borehole televiewer logs and mapped structures of an existing fault with larger damage zone that crosses the stimulated rock volume. We conclude that the coda analysis of active UT measurements complements established imaging methods used during experiments in URLs. In particular, coda analysis is a powerful tool for the detection of damage zones and for monitoring changes in local fracture networks with immediate application for imaging geo-reservoirs considered for exploitation or underground storage of gases and liquids.

Coda

Geophone

Microseism

10.5194/egusphere-egu23-14231

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Seismic Monitoring at the North Anatolian Fault in the Sea of Marmara offshore Istanbul, NW Turkey

EGU General Assembly Conference Abstracts (2010)

Fatih Bulut Marco Bohnhoff Mustafa Aktar Georg Dresen

North Anatolian Fault

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Characterization of aftershock‐fault plane orientations of the 1999 İzmit (Turkey) earthquake using high‐resolution aftershock locations

Geophysical Research Letters (2007)

Fatih Bulut Marco Bohnhoff Mustafa Aktar Georg Dresen

Joint inversion for hypocentral parameters and the velocity field is nowadays a state of the art tool to obtain high‐resolution images of seismically active regions. In this study, we focus on the location accuracy of aftershocks of the 1999 Mw = 7.4 İzmit (NW Turkey) earthquake. We obtained a new velocity model for the region, and depicted its improvement on absolute locations in terms of uncertainty and misfit. Two well‐developed aftershock clusters located in the Akyazı area and Karadere‐Düzce region, were analyzed in detail based on a waveform cross‐correlation approach that allowed improving the location accuracy by a factor of 6. Relocation results reveal that hypocenters form narrow planes of activity that can be correlated with focal mechanisms of the larger aftershocks as well as nearby clouds of activity with no internal structure down to the resolved scale of ∼300 m.

Fault plane

Hypocenter

Focal mechanism

10.1029/2007gl031154

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Citations (49)

Analysis of Microseismicity Framing M_L > 2.5 Earthquakes at The Geysers Geothermal Field, California

Journal of Geophysical Research Solid Earth (2019)

Stephan Bentz Patricia Martínez‐Garzón Grzegorz Kwiatek Georg Dresen Marco Bohnhoff

Abstract Preparatory mechanisms accompanying or leading to nucleation of larger earthquakes have been observed at both laboratory and field scales, but conditions favoring the occurrence of observable preparatory processes are still largely unknown. In particular, it remains a matter of debate why some earthquakes occur spontaneously without noticeable precursors as opposed to events that are preceded by an extended failure process. In this study, we have generated new high‐resolution seismicity catalogs framing the occurrence of 20 M L > 2.5 earthquakes at The Geysers geothermal field in California. To this end, a seismicity catalog of the 11 days framing each large event was created. We selected 20 sequences sampling different hypocentral depths and hydraulic conditions within the field. Seismic activity and magnitude frequency distributions displayed by the different earthquake sequences are correlated with their location within the reservoir. Sequences located in the northwestern part of the reservoir show overall increased seismic activity and low b values, while the southeastern part is dominated by decreased seismic activity and higher b values. Periods of high injection coincide with high b values and vice versa. These observations potentially reflect varying differential and mean stresses and damage of the reservoir rocks across the field. About 50% of analyzed sequences exhibit no change in seismicity rate in response to the large main event. However, we find complex waveforms at the onset of the main earthquake, suggesting that small ruptures spontaneously grow into or trigger larger events.

Microseism

Framing (construction)

10.1029/2019jb017716

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Citations (7)