[STT51-01] Automatic identification of airgun signals observed by ocean bottom seismic network
Keywords:Automatic hypocenter determination, Airgun survey, OBS
Pulse-like signals of relatively high frequency are observed near the source. However, it is difficult to discriminate between natural earthquakes and airgun signals, since distinct features are not seen at a distance from the source. Airgun signals are generated at equal intervals of about 10–30 seconds, and those amplitudes and shapes are similar. In this study, we report an attempt to discriminate between natural earthquakes and airguns by using the autocorrelation by taking into account the similarity of the amplitudes and shapes of the airgun signals.
In the case of the M7.4 off Fukushima Prefecture earthquake, which occurred on November 22, 2016, an airgun survey was performed in the south of the aftershock area, off Ibaraki Prefecture on the same day. We applied the automatic classification method by autocorrelation to this seismic waveform. As a result, the number of aftershocks was reduced by only 2%, whereas the event detection by airgun was reduced by 91%. Furthermore, we applied this method to cases along the Nankai trough, and its effectiveness was also confirmed.
The waveform data are available from the Data Management Center of NIED (https://doi.org/10.17598/NIED.0009).