An <i>M</i><sub>w</sub>8.4 Super Sub-Event Associated with the 2011 <i>M</i><sub>w</sub>9.1 Tohoku Earthquake

DOI Web Site 12 References

Bibliographic Information

Other Title
  • 2011年<i>M</i><sub>w</sub>9.1東北地震に伴った<i>M</i><sub>w</sub>8.4スーパーサブイベント
  • 2011年Mw9.1東北地震に伴ったMw8.4スーパーサブイベント
  • 2011ネン Mw9.1 トウホク ジシン ニ トモナッタ Mw8.4 スーパーサブイベント

Search this article

Abstract

We analyze GPS high sampling records of GEONET and a continuous stress record of the Tono Research Institute of Earthquake Science in Japan observed from the 2011 Mw9.1 Tohoku Earthquake. The most dominant feature in the GPS high sampling records is a main pulse with amplitude of a few meters and a width of around 100 s, the overall feature of which is elucidated by synthetics in a half space with a rectangular fault model with a moment of 2.8×1023 Nm (Mw8.9), starting around 35 s after the JMA origin time. The next dominant feature is a sub-pulse with amplitude of up to a meter and a width of 25-35 s, within the wavetrain of the main pulse, appearing in a transverse component around 25 s after the onset of the main pulse. Record sections of the transverse component reduced by S wave velocity of 3.9 km/s along N30W-N150W directions clearly indicate that the sub-pulse was an SH wave that radiated off the coast of Miyagi Prefecture within the source region of the 2011 Tohoku earthquake. Matching the sub-pulse with synthetics by trial and error, we obtain an extraordinary sub-event model of a left lateral strike slip fault, striking along the N145E direction, which we call a super sub-event. The slip velocity and seismic moment for the super sub-event are around 10 m/s and (4-5)×1022 Nm (Mw8.4), respectively, while the slip and area of faulting cannot be separately solved because of a trade-off between them.

Journal

References(12)*help

See more

Related Projects

See more

Keywords

Details 詳細情報について

Report a problem

Back to top