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Massive Tohoku Earthquake Sent a Seismic Wave That Shifted All of Japan
Gizmodo • • world
Key Points:
- Fifteen minutes after the 2011 magnitude 9 Tohoku earthquake, researchers observed a uniform eastward ground shift of up to 6 millimeters across all of Japan, without any corresponding earthquake event.
- The study led by Sunyoung Park suggests this shift was caused by a powerful ScS seismic wave that traveled deep underground, bounced off Earth’s core, and returned to the surface, reactivating tectonic plate boundaries.
- This is the first known observation of a seismic event triggered by a core-reflected ScS wave, revealing a previously unknown hazard where seismic waves can cause additional shifts long after the main shaking stops.
- The findings imply that such waves may trigger further aftershocks or ruptures far from the initial quake site, expanding the understanding of earthquake hazards and risks.
- Researchers note limitations due to lack of offshore GPS data and are investigating whether similar phenomena occur at other subduction zones, aiming to enhance earthquake preparedness globally.
