The 2010 Beni-Ilmane, Algeria, earthquake sequence: statistical analysis, source parameters, and scaling relationships

摘要

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 x 10(14) to 1.6 x 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 Delta sigma(S)/Delta sigma(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 x 10(16) N m have stress drops that are generally constant, while the stress drops of earthquakes with M-0 2 x 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 gamma 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.