Water depth dependence of correlations in nontidal variations of ocean bottom pressure measurements and ensuing development of methods to detect slow slip events from the seafloor deformation signal

概要

Since the 1990s, slow earthquakes have been found in many subduction zones
worldwide and have been recognized as a common phenomenon found in subduction
zones (Hirose et al., 1999; Ito et al., 2007; Linde et al., 1996; Obara, 2002; Ozawa et al.,
2004). Slow slip events (SSEs) are a type of slow earthquake observed on geodetic time
scales of several days to several years. Some SSEs have been detected in the northern
Hikurangi subduction zone with relatively large signals, predominantly in both offshore
and onshore geodetic time series (Wallace et al., 2016; Woods et al., 2020, 2022).
Offshore and onshore geodetic observations revealed that the SSE that occurred off the
coast of Gisborne in September 2014 extended to a depth of approximately 2 km from
the seafloor to the plate boundary and that the slip amount of the SSE was relatively small
around the seamounts (Wallace et al., 2016). In general, the use of seafloor geodetic
measurements enhances the details of slip distributions of SSEs occurring in shallow
subduction zones. ...