Slow slip events (SSEs), in which tectonic plate interfaces slip slowly and generate seismic rumbling, have been observed in many subduction zones around the world.
These events can provide insight into the accumulation and release ofseismic stress, potentially giving scientists information on the processes generating megathrust quakes.
In southwest Japan, megathrust earthquakes tend to occur along the Nankai Trough, where the Philippine Sea plate subducts beneath the Amurian plate. SSEs have previously been observed along the Nankai Trough using seismological and geodetic instruments. Now, Nishimura et al. show that SSEs can also be identified remotely using Global Navigation Satellite System (GNSS) data.
They were able to successfully detect more than 150 short term SSEs with moment magnitudes ranging from 5.5 to 6.3 that occurred along the Nankai Trough between 1996 and 2012.
Comparing the SSEs identified with GNSS with those identified from tiltmeter data, they find that both methods may have missed some short term SSEs. They note that GNSS is better for detecting large SSEs, while tiltmeters are better for detecting small ones.
Source: Journal of Geophysical Research-Solid Earth,doi:10.1002/jgrb.50222