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Paper in Geology on fault roughness

Together with Thomas Goebel and other co-authors we published a paper in Geology on fault roughness in laboratory stick-slip experiments on rock samples.

Reference:

Goebel, T.H.W., Kwiatek, G., Becker, T.W., Brodsky, E.E. and G. Dresen (2017). What allows seismic events to grow big?: Insights from b-value and fault roughness analysis in laboratory stick-slip experiments. Geology 45 (9): 815-818, DOI: 10.1130/G39147.1 [ Article Page ]

New paper on triggering processes in rock fracture experiments

We published a new manuscript in Physical Review Letters on triggering processes in laboratory experiments on rock samples (with implications to natural and induced seismicity of course!)

Reference

Davidsen, J., Kwiatek, G., Charalampidou, E.-M., Goebel, T., Stanchits, S., Rueck, M., and G. Dresen. Triggering processes in rock fracture. Phys. Res. Lett. 119, 068501, DOI: 10.1103/PhysRevLett.119.068501. [ Article Page ]

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.

A paper on spatial distribution of b-value in North Anatolian Fault Zone

The paper on spatial variations of seismic Gutenberg-Richter b-value along the North Anatolian Fault Zone have been recently published in the Tectonophysics.

Reference:

Raub, C., Martínez-Garzón, P., Kwiatek, G., Bohnhoff, M., and G. Dresen (2017). Variations of seismic b-value at different stages of the seismic cycle along the North Anatolian Fault Zone in northwestern Turkey. Tectonophysics 712-713, 232-248, DOI: 10.1016/j.tecto.2017.05.028. [ Article Page ]

New files to download

Thanks to the policy of BSSA, SRL and PRL, I could upload some published versions of the manuscripts I (co-) authored to induced.pl website. This includes the following papers:

Kwiatek, G., P. Martínez-Garzón, and M. Bohnhoff (2016). HybridMT: A MATLAB/Shell Environment Package for Seismic Moment Tensor Inversion and Refinement, Seismol. Res. Lett. 87, no. 4, 964–976, doi 10.1785/0220150251.

[ Download PDF document (1.75 MB) ]

Martínez-Garzón, P., G. Kwiatek, M. Ickrath, and M. Bohnhoff (2014). MSATSI: A MATLAB Package for Stress Inversion Combining Solid Classic Methodology, a New Simplified User- Handling, and a Visualization Tool, Seismol. Res. Lett. 85, no. 4, 896–904, doi 10.1785/0220130189.

[ Download PDF document (9.92 MB) ]

Davidsen, J., and G. Kwiatek (2013). Earthquake interevent time distribution for induced micro-, nano- and picoseismicity, Phys. Rev. Lett. 110, 068501, doi 10.1103/PhysRevLett.110.068501.

[ Download PDF document (725.13 KB) ]

Davidsen, J., G. Kwiatek, and G. Dresen (2012). No Evidence of Magnitude Clustering in an Aftershock Sequence of Nano- and Picoseismicity, Phys. Rev. Lett. 108, 038501, doi 10.1103/PhysRevLett.108.038501.

[ Download PDF document (146.28 KB) ]

Kwiatek, G., K. Plenkers, and G. Dresen (2011). Source Parameters of Picoseismicity Recorded at Mponeng Deep Gold Mine, South Africa: Implications for Scaling Relations, Bull. Seismol. Soc. Am. 101, no. 6, 2592–2608, doi 10.1785/0120110094.

[ Download PDF document (2.88 MB) ]

Plenkers, K., D. Schorlemmer, and G. Kwiatek (2011). On the Probability of Detecting Picoseismicity, Bull. Seismol. Soc. Am. 101, no. 6, 2579–2591, doi 10.1785/0120110017.

[ Download PDF document (771.19 KB) ]

Naoi, M., M. Nakatani, Y. Yabe, G. Kwiatek, T. Igarashi, and K. Plenkers (2011). Twenty thousand aftershocks of a very small (M2) earthquake and their relations to the mainshock rupture and geological structures, Bull. Seismol. Soc. Am. 101, no. 5, 2399–2407, doi 10.1785/0120100346.

[ Download PDF document (837.38 KB) ]

Kwiatek, G., K. Plenkers, M. Nakatani, Y. Yabe, G. Dresen, and J. Group (2010). Frequency-Magnitude Characteristics Down to Magnitude -4.4 for Induced Seismicity Recorded at Mponeng Gold Mine, South Africa, Bull. Seismol. Soc. Am. 100, no. 3, 1167–1173, doi 10.1785/0120090277.

[ Download PDF document (791.92 KB) ]

Paper in JGR on improved stress tensor inversion from focal mechanism

Another article related to stress tensor inversion has been published in JGR! This one discusses the improved methodology for stress tensor inversion.

Reference:

Martínez-Garzón, P., Y. Ben-Zion, N. Abofalthian, G. Kwiatek, and M. Bohnhoff (2016). A refined methodology for stress inversions of earthquake focal mechanisms. J. Geophys. Res., 121, 8666-8687, DOI: 10.1002/2016JB013493. [ Article Page ]

Abstract:

We develop an improved methodology for reliable high-resolution inversions of focal mechanisms to background stress field orientation and stress ratio R in two or three dimensions. The earthquake catalog is declustered to remove events likely affected strongly by local stress interactions rather than reflecting the large-scale background stress field. The declustered data are discretized with the k-means algorithm into groups containing a number of focal mechanisms between a minimum number Nmin and 2Nmin. Synthetic tests indicate that Nmin ≈ 30 provides stable inversion results under different stress regimes and noise conditions when R ≈ 0.5, while Nmin ≈ 45 is needed for R near 0 or 1. Additional synthetic tests compare the performance of selecting the fault plane of each focal mechanism using (a) the plane with lowest misfit angle between the slip vector from the focal mechanism and shear traction from the stress tensor and (b) the plane with highest instability coefficient representing proximity to the optimally oriented fault for given stress field and friction coefficient. The instability criterion is found to provide more accurate inversion results under all tested stress regimes, stress ratios, and noise conditions. The refined inversion methodology combines selecting fault planes using the instability criterion iteratively with a damped simultaneous inversion of different focal mechanism groups. Results characterizing neighborhoods of discretized domains merged during the damped inversion provide high-resolution information independent of the discretization. Some aspects of the methodology are illustrated with focal mechanism data from the San Jacinto Fault Zone in Southern California.