The Seafloor and TsunamiResearch by Manoa’s Gregory Moore could help assess tsunami risks. Read more
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Nakai Trough seismogenic zone experiment.
The Seafloor and Tsunami
Research by Manoa Professor Gregory Moore along with geoscientists from Japan and Texas may help explain why part of the seafloor near the southwest coast of Japan is particularly good at generating devastating tsunamis, such as the 1944 Tonankai event, which killed at least 1,200 people. The findings will help scientists assess the risk of giant tsunamis in other regions of the world. The results were published in the journal Science.
The team used a commercial ship to collect three-dimensional seismic data that reveals the structure of Earth’s crust below a region of the Pacific seafloor known as the Nankai Trough. The resulting images are akin to ultrasounds of the human body.
The 3-D seismic images allowed the researchers to reconstruct how layers of rock and sediment have cracked and shifted over time. They confirmed the existence of a major fault that runs from a region known to unleash earthquakes about 6 miles deep right up to the seafloor. When an earthquake happens, the fault allows it to reach up and move the seafloor up or down, carrying a column of water with it and setting up a series of tsunami waves that spread outward.
The team also discovered that the recent fault activity, probably including the slip that caused the 1944 event, has shifted to landward branches of the fault, becoming shallower and steeper than it was in the past.
Read the news release. Go to the School of Ocean and Earth Sciences and Technology to view full image.
