Publication Date:
2018-10-29
Description:
Source parameters were estimated for the 18 largest events (M D ≥ 4) of the 2010 Beni-Ilmane earthquake sequence (north-central Algeria) using data recorded by permanent broadband seismic stations of the Algeria Digital Seismic Network (ADSN). Displacement spectra of P and S waves were estimated using a Brune seismic source model to compute spectral parameters. Spectra were corrected to account for path effects and near-surface attenuation. The average seismic moments estimated from P and S wave spectra ranged from 5.5 × 10 14 to 1.6 × 10 17 N m, with a logarithmic mean M 0 (S)/M 0 (P) ratio of 0.96. Source radii ranged from 735 to 2266 m with an average r(S)/r(P) value of 0.99. Stress drops varied from 0.2 to 11 MPa with an average Δσ(S)/Δσ(P) ratio of 1.08. Corner frequencies (f c ) vary from 0.8 to 2.4 Hz, and moment magnitudes (M w ) range from 3.8 to 5.4. Scaling relations of seismic moments, source radii, and stress drops indicate that events with M 0 ≥ 2 × 10 16 N m have stress drops that are generally constant, while the stress drops of earthquakes with M 0 〈 2 × 10 16 N m decrease with decreasing seismic moment. The source parameters of the 1960 Melouza (now Beni-Ilmane) moderate earthquake are also estimated from these scaling relationships. Finally, we find low b and γ values in the Gutenberg–Richter and gamma function laws. The seismic sequence is discussed in the context of the active tectonics of the Beni-Ilmane fault system. © 2018, Springer Nature B.V.
Print ISSN:
1383-4649
Electronic ISSN:
1573-157X
Topics:
Geosciences
,
Physics
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