Frequency analysis of the 2004 Sumatra-Andaman earthquake using spectral seismograms

摘要

Frequency analysis of the Sumatra-Andaman earthquake of 2004, one of the most significant and best-recorded earthquakes, is based on spectral seismograms obtained from their broadband seismograms. The Sumatra-Andaman earthquake is found to have a wide-range frequency content of P-wave radiation during the rupturing process. On the basis of stacking spectral seismograms we distinguished four time events of the rupturing process of a total length of about 540 s. The frequency, f_(max), is the highest for the first event (0.163 Hz in time interval 0-88 s), lowest for the second - which is the strongest (0.075 Hz in time interval 88-204 s). For third and fourth events frequencies are similar (0.089 and 0.082 Hz in time intervals 204-452 and 452-537 s, respectively). The frequency also shows an azimuthal dependence (±0.02 Hz). Azimuths for which the frequency, f_(max), has maximum and minimum values are 203-222° and 23-42°, respectively. These observations are discussed in relation to previously published papers on this topic.