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Step-Like Motion Associated With Near-Source ScS Phase From the 2011 Tohoku-Oki Earthquake: Potential Triggering by ScS

Description: 

The Mw 9.0 2011 Tohoku-Oki earthquake generated a strong ScS phase with the peak-to-peak amplitude larger than 1 cm in Japan. This near-source ScS phase was recorded at nearly all sites of GEONET, a network of more than 1000 GPS instruments that are densely covering Japan. Even though the individual GPS timeseries data are noisy, stacking 30+ records at adjacent sites results in clean signals of the ScS phase. In addition to the conventional ScS waveforms, the stacked data exhibit an eastward step-like displacement with an amplitude up to about 5 mm, superposed on top of the ScS wave. We show that the observation is robust despite the noise in GPS data and may be supported by seismic data as well. We find that the likely mechanism for our observation is slip triggered by ScS phase which arrives nearly simultaneously throughout Japan. We could rule out other mechanisms such as the near-field term and long moment rate function of the source.

Session: New Observations and Modeling of Triggered Seismicity [Poster]

Type: Poster

Date: 4/19/2023

Presentation Time: 08:00 AM (local time)

Presenting Author: Sunyoung Park

Student Presenter: No

Invited Presentation: 

Authors