Slow-motion earthquakes may also lead to tsumis

New York, May 6: Slow-motion earthquakes or ‘slow-slip events’ can rupture the shallow portion of a fault that also moves in large, tsumi-generating earthquakes, new research has found. Slow-slip events are similar to earthquakes, but instead of releasing strain between two tectonic plates in seconds, they do it over days to weeks, creating quiet, centimetre-sized shifts in the landscape.

Using a network of highly sensitive seafloor pressure recorders, an intertiol team of researchers from the US, Japan and New Zealand detected a slow-slip event off the east coast of New Zealand.

“Our results clearly show that shallow, slow-slip event source areas are also capable of hosting seismic rupture and generating tsumis,” said study co-author Yoshihiro Ito, professor at Kyoto University in Japan.

“This increases the need to continuously monitor shallow, offshore slow-slip events at subduction zones, using permanent monitoring networks similar to those that have been established offshore of Japan,” Ito noted.

The study, published in the jourl Science, was undertaken at the Hikurangi subduction zone, where the Pacific Plate subducts beneath New Zealand’s North Island.

The slow-slip event lasted two weeks, resulting in 15-20 centimetres of movement along the fault that lies between New Zealand and the Pacific Plate, a distance equivalent to three to four years of background plate motion. (IANS)