TY - JOUR
T1 - Extracting Near-Field Seismograms From Ocean-Bottom Pressure Gauge Inside the Focal Area
T2 - Application to the 2011 Mw 9.1 Tohoku-Oki Earthquake
AU - Kubota, Tatsuya
AU - Saito, Tatsuhiko
AU - Tsushima, Hiroaki
AU - Hino, Ryota
AU - Ohta, Yusaku
AU - Suzuki, Syuichi
AU - Inazu, Daisuke
N1 - Funding Information:
This study was financially supported by the research project “Research concerning Interaction between the Tokai, Tonankai, and Nankai Earthquakes” of Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan, and by Japan Society for the Promotion of Science (JSPS) KAKENHI Grant Numbers JP20244070, JP26000002, JP15K17752, JP19H00708, JP19H02409, 19H05596, JP19K04021, and JP19K14818. TK thanks Yoshihiro Ito of Kyoto University for fruitful comments. TK also thanks the captains and crews of these vessels and the staff and technicians at ERI for their efforts for their operation. The authors thank the Editor Germán Prieto, the Associate Editor, and Prof. Thorne Lay and another anonymous reviewer for their constructive comments.
Publisher Copyright:
© 2021. The Authors.
PY - 2021/4/16
Y1 - 2021/4/16
N2 - Recent studies have shown that ocean-bottom pressure gauges (OBPs) can record seismic waves in addition to tsunamis and seafloor permanent displacements, even if they are installed inside the focal area where the signals are extremely large. We developed a method to extract dynamic ground motion waveforms from near-field OBP data consisting of a complex mixture of various signals, based on an inversion analysis along with a theory of tsunami generation. We applied this method to the OBP data of the 2011 Tohoku-Oki earthquake. We successfully extracted the low-frequency vertical seismograms inside the focal area (f < ∼0.05 Hz), although those of the Mw ∼9 megathrust earthquake had never previously been reported. The seismograms suggested two dominant energy releases around the hypocenter. The seismic wave signals recorded by the near-field OBP will be important not only to reveal earthquake ruptures and tsunami generation processes but also to conduct real-time tsunami forecasts.
AB - Recent studies have shown that ocean-bottom pressure gauges (OBPs) can record seismic waves in addition to tsunamis and seafloor permanent displacements, even if they are installed inside the focal area where the signals are extremely large. We developed a method to extract dynamic ground motion waveforms from near-field OBP data consisting of a complex mixture of various signals, based on an inversion analysis along with a theory of tsunami generation. We applied this method to the OBP data of the 2011 Tohoku-Oki earthquake. We successfully extracted the low-frequency vertical seismograms inside the focal area (f < ∼0.05 Hz), although those of the Mw ∼9 megathrust earthquake had never previously been reported. The seismograms suggested two dominant energy releases around the hypocenter. The seismic wave signals recorded by the near-field OBP will be important not only to reveal earthquake ruptures and tsunami generation processes but also to conduct real-time tsunami forecasts.
KW - dynamic pressure change
KW - ocean-bottom pressure gauge
KW - seafloor ground motion
KW - the 2011 Tohoku-Oki earthquake
KW - tsunami
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U2 - 10.1029/2020GL091664
DO - 10.1029/2020GL091664
M3 - Article
AN - SCOPUS:85104301917
SN - 0094-8276
VL - 48
JO - Geophysical Research Letters
JF - Geophysical Research Letters
IS - 7
M1 - e2020GL091664
ER -