Japanese researchers unearth important revelation about mega-earthquakes, potentially transforming prediction and preparedness.
Japanese researchers unearth an important revelation about mega-earthquakes, uncovering that it’s not just shallow energy release, but also deep-seated tectonic stress that triggers devastating seismic events, potentially transforming earthquake prediction and preparedness.
In a quest to untangle the intricate dance of tectonic plates during mega-earthquakes, a team of researchers from Tohoku University and the National Research Institute for Earth Science and Disaster Resilience has delved into the devastating 2011 Tohoku-Oki quake, otherwise known as the Great East Japan Earthquake, for answers.
The crux of the researchers’ novel study lies in the exploration of what drives the gigantic shallow slips and the devastating tsunamis they trigger. Contrary to previous belief, the study revealed that these seismic events are not solely due to energy released at the plate boundaries near the seafloor. Rather, it is the deep-seated stress release within the tectonic plates that plays an equally crucial part. The researchers’ findings were published in the journal Progress in Earth and Planetary Science.
Mega-earthquakes like Tohoku-Oki occur in subduction zones, where one tectonic plate sinks beneath another. As these plates interlock, strain builds up, ultimately culminating in an earthquake. But what made the Tohoku-Oki quake unleash such enormous energy, especially near the trench? The answer, this study showed, lies not only in the shallows, but also in the deeper layers where substantial stress release and strain accumulation occur.
The team used innovative methods to estimate the slip and stress drop distributions during the quake, utilising tsunami data from ocean-bottom pressure gauges located directly above the fault area—a previously untapped data source.
“Our findings indicate the colossal slip at the shallowest portion was triggered by significant stress release from the deeper sections of the tectonic plate, rather than just surface energy accumulation,” noted Tatsuya Kubota, lead and corresponding author of the study.
This ground-breaking study upends the conventional notion that the shallow parts of the plate interface are solely accountable for mega-slips during earthquakes. Instead, it suggests a symbiotic relationship between shallow and deep stress releases, resulting in seismic events.
In essence, this research paints a more comprehensive picture of the complex dynamics of earthquakes, bridging the gap between the behaviour of shallow and deep plate sections in a delicate balance of strain and release. It also opens a new path to predict future mega-earthquakes and their potential to spawn catastrophic tsunamis. With this fresh perspective, it may be possible for scientists to evaluate whether sufficient strain energy is gathering in the deep areas that could trigger significant seismic activity.
Moving forward, the researchers aim to leverage these findings to further dissect the subtle mechanisms that drive these massive seismic events. Ultimately, these insights could help enhance the safety measures and resilience strategies for communities situated in earthquake-prone regions, equipping them with the necessary defences against these formidable natural forces.