10:30 〜 10:45
[S09-2-01] Remote triggering of earthquakes as a possible stress-meter: the case of the 2016 M7.3 Kumamoto (Japan) mainshock
Activation of seismicity at remote locations due to the passage of seismic waves from large earthquakes is well-documented. However, distant earthquake triggering is scarce in Japan, with the notable exception of the remote seismicity activated by the 2011 M9.0 Tohoku-oki earthquake. Here we report on a relatively widespread remote triggering of small events following the 2016 M7.3 Kumamoto earthquake and hypothesize on its causes.
We have processed waveform data recorded by high-sensitivity Hi-net and broadband F-net stations, operated by NIED, as well as JMA stations.
The activated seismicity correlates well with the passage of surface waves from the Kumamoto earthquake. The furthest triggered event was observed at Akan volcano (Hokkaido) at ~1630 km epicentral distance. Triggering has been also observed at other volcanoes in Tohoku, Chubu and around Izu Peninsula. Some active fault areas like Tottori and Noto Peninsula were also activated. The dynamic stresses at the triggered locations range from several to tens of kPa. Since most of the remotely triggered earthquakes were observed at volcanoes, the excitation of crustal fluids was likely the main triggering mechanism.
We found that the regions activated this time, in particular some volcanic areas in Tohoku, have been also activated after the 2011 Tohoku-oki earthquake. We hypothesize that mechanical weakening of a pressurized crust in these regions due to the 2011 megathrust might be responsible for an increased trigger-ability. In addition, the activation of some active crustal faults might be related to the levels of tectonic stress along these fault lines. These observations suggest that remote triggering might be used as a stress-meter at volcanoes and active faults.
Reference paper:
Enescu, B., Shimojo, K., Opris, A., and Y. Yagi, Remote triggering of seismicity at Japanese volcanoes following the 2016 M7.3 Kumamoto earthquake, Earth, Planets and Space, 68:165, doi:10.1186/s40623-016-0539-5, 2016.
We have processed waveform data recorded by high-sensitivity Hi-net and broadband F-net stations, operated by NIED, as well as JMA stations.
The activated seismicity correlates well with the passage of surface waves from the Kumamoto earthquake. The furthest triggered event was observed at Akan volcano (Hokkaido) at ~1630 km epicentral distance. Triggering has been also observed at other volcanoes in Tohoku, Chubu and around Izu Peninsula. Some active fault areas like Tottori and Noto Peninsula were also activated. The dynamic stresses at the triggered locations range from several to tens of kPa. Since most of the remotely triggered earthquakes were observed at volcanoes, the excitation of crustal fluids was likely the main triggering mechanism.
We found that the regions activated this time, in particular some volcanic areas in Tohoku, have been also activated after the 2011 Tohoku-oki earthquake. We hypothesize that mechanical weakening of a pressurized crust in these regions due to the 2011 megathrust might be responsible for an increased trigger-ability. In addition, the activation of some active crustal faults might be related to the levels of tectonic stress along these fault lines. These observations suggest that remote triggering might be used as a stress-meter at volcanoes and active faults.
Reference paper:
Enescu, B., Shimojo, K., Opris, A., and Y. Yagi, Remote triggering of seismicity at Japanese volcanoes following the 2016 M7.3 Kumamoto earthquake, Earth, Planets and Space, 68:165, doi:10.1186/s40623-016-0539-5, 2016.