[SCG59-P03] Magnitude estimation by using ocean-bottom pressure gauge data
Keywords:DONET, earthquake magnitude, pressure gauge, Earthquake Early Warning
We analyzed the waveforms after integrating the observed pressure gauge data and applying a high-pass filter with a corner period of 6 s. In the case of ocean-bottom stations deployed in a water depth of more than 2,200 m, the amplitude of pressure waveforms in this period band is roughly consistent with the vertical amplitude of ocean-bottom velocity (e.g., Matsumoto et al., 2012). The period band of less than 6 s corresponds to that used for estimating the amplitude magnitude of the unified hypocenter catalogue and EEW by JMA. We constructed the empirical equation between the magnitude and the filtered amplitude data and estimated the magnitude for each event data.
Our results show that the magnitude estimated from using pressure gauge data correlates well with that in the JMA list. The deviation (two sigma) is 0.70, which is the same value as that estimated from using three component data of accelerometer. For the event data of the 2016 earthquake (Mjma 6.5), the estimated magnitudes by accelerometer data are 6.64–8.34, while those by pressure gauge data are 6.33–6.81, indicating that the magnitude estimation using the latter data provides less amplification and stable results. The pressure gauge installed at DONET stations may be relatively low sensor hysteresis and less effects of sensor rotation on short-period component of waveforms compared with those of accelerometer.