The 2007 Medea Seismic Sequence, North-Central Algeria: Source Parameters, Stress Tensor, and Static Stress Changes

Autor: H. Beldjoudi, G. Dabouz, Abdelkrim Yelles-Chaouche, Yahia Mohammedi, Bertrand Delouis, Oualid Boulahia
Rok vydání: 2021
Předmět:
Zdroj: Pure and Applied Geophysics. 178:3313-3337
ISSN: 1420-9136
0033-4553
DOI: 10.1007/s00024-021-02827-7
Popis: Dense seismic networks provide the opportunity to better understand seismogenic processes in tectonically active regions. The Algerian Digital Seismic Network was strengthened following the 10 October 1980 Ms 7.3 El Asnam and 21 May 2003 Mw 6.8 Bournerdes earthquakes, such that the source parameters of small- to moderate-magnitude earthquakes in northern Algeria can now be computed. Here we examine the 2007 seismic sequence recorded in the Medea region (north-central part of Algeria). We calculate the seismic sources of three moderate events that occurred between May and August 2007 using near-field waveform modeling, and obtain moment magnitudes of 4.4, 4.1, and 4.6, with fault planes oriented N63°E, N15°E, and N219°E, respectively. We use displacement spectra to estimate the corner frequency fc and spectral flat level then use these to recalculate the seismic moment and moment magnitude. The stress tensor obtained by inverting 13 focal mechanisms from events near the 2007 sequence exhibits a well-constrained compressional axis with a subhorizontal N335°E-trending σ1 axis (plunge 7°). We calculate the static stress changes to understand the connections between these three events. The results indicate an interaction between the faults related to these events during the earthquake sequence. We conclude that these events likely occurred on the unstudied extensions of mapped faults, and that the epicentral area therefore has moderate seismogenic potential.
Databáze: OpenAIRE
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