*jin deng
Keywords:very low-frequency earthquakes(VLF), Low-frequency events, the 2008’Wenchuan 8.0 earthquake
This study reports discovery of very low frequency earthquakes (VLFEs) that occurred 4 h before the 2008 Ml=8.0 Wenchuan earthquake. The VLF events swarm is of 35 events, recorded by China seismic monitoring network between 10:00 to 12:00 on 12 May 2008. The VLFEs are characterized by waveform durations of 1000-2000 s, magnitudes of Mw2-4 and focal depths 25-40 km deeper than those of natural earthquakes in the same regions. The VLFs last arrived phase is reflected wave and clearly to be identified in VLFs waveform, as fig.1. The VLF waveforms is from more than one events with its Pg arrival times.
The VLFEs swarm can be one of important precursor evidence before the large earthquake.