Aftershocks triggered by fluid intrusion: Evidence for the aftershock sequence occurred 2014 in West Bohemia/Vogtland

0463859 - GFÚ 2017 RIV US eng J - Journal Article
Hainzl, S. - Fischer, Tomáš - Čermáková, Hana - Bachura, M. - Vlček, J.
Aftershocks triggered by fluid intrusion: Evidence for the aftershock sequence occurred 2014 in West Bohemia/Vogtland.
Journal of Geophysical Research-Solid Earth. Roč. 121, č. 4 (2016), s. 2575-2590. ISSN 2169-9313. E-ISSN 2169-9356
R&D Projects: GA ČR GAP210/12/2336; GA MŠMT LM2010008
Institutional support: RVO:67985530
Keywords : pore-pressure diffusion * 2000 earthquake swarm * Vogtland/Western Bohemia
Subject RIV: DC - Siesmology, Volcanology, Earth Structure
Impact factor: 3.350, year: 2016

The West Bohemia/Vogtland region, central Europe, is well known for its repeating swarm activity. However, the latest activity in 2014, although spatially overlapping with previous swarm activity, consisted of three classical aftershock sequences triggered by M(L)3.5, 4.4, and 3.5 events. To decode the apparent system change from swarm-type to mainshock-aftershock characteristics, we have analyzed the details of the major M(L)4.4 sequence based on focal mechanisms and relocated earthquake data. Our analysis shows that the mainshock occurred with rotated mechanism in a step over region of the fault plane, unfavorably oriented to the regional stress field. Most of its intense aftershock activity occurred in-plane with classical characteristics such as (i) the maximum magnitude of the aftershocks is significantly less than the mainshock magnitude and (ii) the decay can be well fitted by the Omori-Utsu law. However, the absolute number of aftershocks and the fitted Omori-Utsu c and p parameters are much larger than for typical sequences. By means of the epidemic-type aftershock sequence model, we show that an additional aseismic source with an exponentially decaying strength triggered a large fraction of the aftershocks.
Permanent Link: http://hdl.handle.net/11104/0262952