@article{BlankeKwiatekGoebeletal.2021,
  author    = {Blanke, Aglaja and Kwiatek, Grzegorz and Goebel, Thomas H. W. and Bohnhoff, Marco and Dresen, Georg},
  title     = {Stress drop-magnitude dependence of acoustic emissions during laboratory stick-slip},
  series = {Geophysical journal international / the Royal Astronomical Society, the Deutsche Geophysikalische Gesellschaft and the European Geophysical Society},
  volume    = {224},
  journal   = {Geophysical journal international / the Royal Astronomical Society, the Deutsche Geophysikalische Gesellschaft and the European Geophysical Society},
  number    = {2},
  publisher = {Oxford Univ. Press},
  address   = {Oxford},
  issn      = {0956-540X},
  doi       = {10.1093/gji/ggaa524},
  pages     = {1372 -- 1381},
  year      = {2021},
  abstract  = {Earthquake source parameters such as seismic stress drop and corner frequency are observed to vary widely, leading to persistent discussion on potential scaling of stress drop and event size. Physical mechanisms that govern stress drop variations arc difficult to evaluate in nature and are more readily studied in controlled laboratory experiments. We perform two stick-slip experiments on fractured (rough) and cut (smooth) Westerly granite samples to explore fault roughness effects on acoustic emission (AE) source parameters. We separate large stick-slip events that generally saturate the seismic recording system from populations of smaller AE events which are sensitive to fault stresses prior to slip. AE event populations show many similarities to natural seismicity and may be interpreted as laboratory equivalent of natural microseismic events. We then compare the temporal evolution of mechanical data such as measured stress release during slip to temporal changes in stress drops derived from Alis using the spectral ratio technique. We report on two primary observations: (1) In contrast to most case studies for natural earthquakes, we observe a strong increase in seismic stress drop with AE size. (2) The scaling of stress drop with magnitude is governed by fault roughness, whereby the rough fault shows a more rapid increase of the stress drop magnitude relation with progressing large stick-slip events than the smooth fault. The overall range of AE sizes on the rough surface is influenced by both the average grain size and the width of the fault core. The magnitudes of the smallest AE events on smooth faults may also be governed by grain size. However, AEs significantly grow beyond peak roughness and the width of the fault core. Our laboratory tests highlight that source parameters vary substantially in the presence of fault zone heterogeneity (i.e. roughness and narrow grain size distribution), which may affect seismic energy partitioning and static stress drops of small and large AE events.},
  language  = {en}
}
@article{DavidsenKwiatekCharalampidouetal.2017,
  author    = {Davidsen, Joern and Kwiatek, Grzegorz and Charalampidou, Elli-Maria and Goebel, Thomas H. W. and Stanchits, Sergei and Rueck, Marc and Dresen, Georg},
  title     = {Triggering Processes in Rock Fracture},
  series = {Physical review letters},
  volume    = {119},
  journal   = {Physical review letters},
  publisher = {American Physical Society},
  address   = {College Park},
  issn      = {0031-9007},
  doi       = {10.1103/PhysRevLett.119.068501},
  pages     = {8},
  year      = {2017},
  abstract  = {We study triggering processes in triaxial compression experiments under a constant displacement rate on sandstone and granite samples using spatially located acoustic emission events and their focal mechanisms. We present strong evidence that event-event triggering plays an important role in the presence of large-scale or macrocopic imperfections, while such triggering is basically absent if no significant imperfections are present. In the former case, we recover all established empirical relations of aftershock seismicity including the Gutenberg-Richter relation, a modified version of the Omori-Utsu relation and the productivity relation-despite the fact that the activity is dominated by compaction-type events and triggering cascades have a swarmlike topology. For the Gutenberg-Richter relations, we find that the b value is smaller for triggered events compared to background events. Moreover, we show that triggered acoustic emission events have a focal mechanism much more similar to their associated trigger than expected by chance.},
  language  = {en}
}
@article{DresenKwiatekGoebeletal.2020,
  author    = {Dresen, Georg and Kwiatek, Grzegorz and Goebel, Thomas H. W. and Ben-Zion, Yehuda},
  title     = {Seismic and aseismic preparatory processes before large stick-slip failure},
  series = {Pure and applied geophysics},
  volume    = {177},
  journal   = {Pure and applied geophysics},
  number    = {12},
  publisher = {Springer},
  address   = {Basel},
  issn      = {0033-4553},
  doi       = {10.1007/s00024-020-02605-x},
  pages     = {5741 -- 5760},
  year      = {2020},
  abstract  = {Natural earthquakes often have very few observable foreshocks which significantly complicates tracking potential preparatory processes. To better characterize expected preparatory processes before failures, we study stick-slip events in a series of triaxial compression tests on faulted Westerly granite samples. We focus on the influence of fault roughness on the duration and magnitude of recordable precursors before large stick-slip failure. Rupture preparation in the experiments is detectable over long time scales and involves acoustic emission (AE) and aseismic deformation events. Preparatory fault slip is found to be accelerating during the entire pre-failure loading period, and is accompanied by increasing AE rates punctuated by distinct activity spikes associated with large slip events. Damage evolution across the fault zones and surrounding wall rocks is manifested by precursory decrease of seismic b-values and spatial correlation dimensions. Peaks in spatial event correlation suggest that large slip initiation occurs by failure of multiple asperities. Shear strain estimated from AE data represents only a small fraction (< 1\%) of total shear strain accumulated during the preparation phase, implying that most precursory deformation is aseismic. The relative contribution of aseismic deformation is amplified by larger fault roughness. Similarly, seismic coupling is larger for smooth saw-cut faults compared to rough faults. The laboratory observations point towards a long-lasting and continuous preparation process leading to failure and large seismic events. The strain partitioning between aseismic and observable seismic signatures depends on fault structure and instrument resolution.},
  language  = {en}
}
@techreport{AdriaansGrieseAuspurgetal.2021,
  author    = {Adriaans, Jule and Griese, Florian and Auspurg, Katrin and Bledow, Nona and Bohmann, Sandra and Busemeyer, Marius R. and Delhey, Jan and Goebel, Jan and Groh-Samberg, Olaf and Heckhausen, Jutta and Hinz, Thomas and Kroh, Martin and Lengfeld, Holger and Lersch, Philipp M. and Liebig, Stefan and Richter, David and Sachweh, Patrick and Schupp, J{\"u}rgen and Schwerdt, Guido and Verwiebe, Roland},
  title     = {Dokumentation zum Entwicklungsprozess des Moduls Einstellungen zu sozialer Ungleichheit im SOEP (v38)},
  series = {SOEP survey papers, series B - survey reports (Methodenberichte)},
  volume    = {1071},
  journal   = {SOEP survey papers, series B - survey reports (Methodenberichte)},
  publisher = {Deutsches Institut f{\"u}r Wirtschaftsforschung (DIW)},
  address   = {Berlin},
  issn      = {2193-5580},
  pages     = {35},
  year      = {2021},
  abstract  = {Im Rahmen eines einj{\"a}hrigen Entwicklungsprozesses wurde das Fragebogenmodul "Einstellungen zu sozialer Ungleichheit" unter der Leitung der Infrastruktureinrichtung SOEP entwickelt und in der 38. Welle der Haupterhebung des Sozio-oekonomischen Panels erstmalig erhoben. Das finale Fragebogenmodul umfasst 43 Items zu den Themenbereichen Soziale Vergleiche, Soziale Mobilit{\"a}t, Sozialstaat und Nicht-materielle Ungleichheit. In der Tradition des SOEP als forschungsbasierte Infrastruktureinrichtung erfolgte die Fragebogenentwicklung in enger Zusammenarbeit mit externen Forschenden aus dem Bereich der Einstellungs- und Ungleichheitsforschung. Neben der etablierten Nutzung des SOEP Innovation Samples (SOEP-IS) f{\"u}r quantitative Pretests neu entwickelter Fragen kam erstmals ein kognitiver Pretest zum Einsatz. Der vorliegende Bericht dokumentiert den Entwicklungsprozess von der Konzeption bis zum finalen Fragebogen.},
  language  = {de}
}