Repeating short- and long-term slow slip events with deep tremor activity around the Bungo channel region, southwest Japan

Abstract

We report the repeating occurrence of short-and long-term slow slip events (SSE) which are accompanied by deep tremor activity around the Bungo channel region, southwest Japan. Both of these activities are detected by NIED Hi-net, which is composed of densely distributed observatories equipped with a set of tiltmeter and a highsensitivity seismograph. Since the short-term SSE is small in magnitude, GPS can detect only the long-term SSE. Some of these episodes have nearly the same surface deformation pattern. This shows the existence of 'slow slip patches' on a plate interface, where the episodic slow slip is the characteristic slip behavior. We observe a change in periodicity and size of the short-term episode after the onset of the long-term SSE. Moreover, the long-term slow slip accelerates when the short-term activity takes place. This suggests that there is an interaction between these two types of SSEs.

Scaling Relationships of Source Parameters for Slow Slip Events

“…There are two sources for the dataset used in this study: source parameters inferred directly from the slip distributions of Schmidt and Gao (2010) for the Cascadia subduction zone and source parameters reported in the literature for other subduction zones (e.g., Obara et al, 2004;Brown et al, 2005;Douglas et al, 2005;Hirose and Obara, 2005;Wallace and Beavan, 2006;Ito and Obara, 2006;Hirose and Obara, 2006;CorreaMora et al, 2008CorreaMora et al, , 2009Hirose and Obara, 2010;Sekine et al, 2010; see references in Ⓔ Table S1, available in the electronic supplement to this paper). Additionally, we also include documented aseismic slip on the San Andreas fault (Linde et al, 1996) and Hawaii's south rift zone (Segall et al, 2006;Montgomery-Brown et al, 2009).…”

Long-term slow slip events along the Nankai trough subduction zone after the 2011 Tohoku earthquake in Japan

“…Data are from Yagi et al (1999) low-frequency earthquakes occur (see Fig. 1a) (Obara 2002), while long-term slow slip events, which last more than several months, occur in the shallower area of the transition zone up-dip of the low-frequency earthquake area (e.g., Hirose and Obara 2005;Ozawa et al 2013;Takagi et al 2016). In addition, Yarai and Ozawa (2013) showed that the afterslip and long-term slow slip events occur in a region deeper than the coseismic slip area in the Hyuga-nada region, southwest Japan.…”

Average slip rate at the transition zone on the plate interface beneath the Kii Peninsula, Japan, estimated from deep low-frequency tremors

“…Obara, 2002), and short-term and long-term slow slip events (SSE) (e.g. Hirose and Obara, 2005). These events are observed at the transition zone between unstable and stable slip zones on the plate interface.…”