Microearthquake mechanism from wave amplitudes recorded by a close-to-surface seismic array at Ocnele Mari, Romania

0428783 - GFÚ 2015 RIV GB eng J - Journal Article
Jechumtálová, Zuzana - Šílený, Jan - Trifu, C.-I.
Microearthquake mechanism from wave amplitudes recorded by a close-to-surface seismic array at Ocnele Mari, Romania.
Geophysical Journal International. Roč. 197, č. 3 (2014), s. 1608-1626. ISSN 0956-540X. E-ISSN 1365-246X
R&D Projects: GA ČR GAP210/10/1728; GA ČR GAP210/12/2235
EU Projects: European Commission(XE) 230669 - AIM
Institutional support: RVO:67985530
Keywords : inverse theory * earthquake source observation * computational seismology * fractures and faults * mechanic, theory, and modelling
Subject RIV: DC - Siesmology, Volcanology, Earth Structure
Impact factor: 2.560, year: 2014

The resolution of event mechanism is investigated in terms of the unconstrained moment tensor (MT) source model and the shear-tensile crack (STC) source model representing a slip along the fault with an off-plane component. Data are simulated as recorded by the actual seismic array installed at Ocnele Mari (Romania), where sensors are placed in shallow boreholes. Noise is included as superimposed on synthetic data, and the analysis explores how the results are influenced (i) by data recorded by the complete seismic array compared to that provided by the subarray of surface sensors, (ii) by using three- or one-component sensors and (iii) by inverting P- and S-wave amplitudes versus P-wave amplitudes only. The orientation of the pure shear fracture component is resolved almost always well. On the other hand, the noise increase distorts the non-double-couple components (non-DC) of the MT unless a highquality data set is available. The STC source model yields considerably less spurious non-shear fracture components. Incorporating recordings at deeper sensors in addition to those obtained from the surface ones allows for the processing of noisier data.
Permanent Link: http://hdl.handle.net/11104/0234051