Disputable non-double-couple mechanisms of several strong earthquakes: second-degree moment approach

0396790 - GFÚ 2014 RIV US eng J - Journal Article
Adamová, Petra - Šílený, Jan
Disputable non-double-couple mechanisms of several strong earthquakes: second-degree moment approach.
Bulletin of the Seismological Society of America. Roč. 103, č. 5 (2013), s. 2836-2849. ISSN 0037-1106. E-ISSN 1943-3573
R&D Projects: GA ČR GAP210/10/0296
Institutional support: RVO:67985530
Keywords : Izmit Turkey earthquake * 1995 Kobe earthquake * rupture processes
Subject RIV: DC - Siesmology, Volcanology, Earth Structure
Impact factor: 1.964, year: 2013

The earthquake source mechanism (description of the geometry of the source and its strength in terms of forces equivalent to rupturing of the rock mass) is routinely modeled as a moment tensor (MT) describing the earthquake focus as a point. However, sometimes this approximation is not satisfied, and seismic radiation keeps the directivity due to the finite extent of the source. Inversion into the MT then may yield a biased mechanism. Synthetic study in the Adamová and Šílený (2010) demonstrated the appearance of spurious non-double-couple components in the mechanism even for a pure double-couple (DC) source. Their method was designed to reduce the spurious source components by using the second-degree moments to evaluate their contribution into the records and subtract it from the data. Here we applied the procedure to five moderate to large regional events with large nonshear components. They are mostly located on large tectonic faults where predominantly pure shear slip is expected. We studied one event on the prominent North Anatolian fault, three events in the Pacific area, and one event in Bolivia.
Permanent Link: http://hdl.handle.net/11104/0224510