Principal earthquakes: Theory and observations from the 2008 West Bohemia swarm

0363814 - GFÚ 2012 RIV NL eng J - Journal Article
Vavryčuk, Václav
Principal earthquakes: Theory and observations from the 2008 West Bohemia swarm.
Earth and Planetary Science Letters. Roč. 305, č. 3-4 (2011), s. 290-296. ISSN 0012-821X. E-ISSN 1385-013X
R&D Projects: GA AV ČR IAA300120801
Institutional research plan: CEZ:AV0Z30120515
Keywords : earthquake * failure criterion * fault friction * focal mechanism * tectonic stress
Subject RIV: DC - Siesmology, Volcanology, Earth Structure
Impact factor: 4.180, year: 2011

Earthquakes that occur on optimally oriented fault planes with respect to the tectonic stress regime display two distinct focal mechanisms and are fundamental characteristics of each seismically active region. These earthquakes, which we term 'principal', need not coincide with the strongest earthquakes or need not occur along the major active faults in the region. Stability analysis of diversely oriented fault planes under a given stress reveals that the focal mechanisms connected with unstable fault planes should not be very distinct from those of the principal earthquakes. The P/T axes form clusters with a typical two-wing or 'butterfly' pattern. This pattern is particularly visible when constructing the failure curves defined as a projection of the Mohr-Coulomb failure criterion in the Mohr's diagram onto the focal sphere. The position, shape and size of the failure curves depend on the stress orientation, shape ratio, friction and on the size of the instability area in the Mohr's diagram.
Permanent Link: http://hdl.handle.net/11104/0199470