Japan Geoscience Union Meeting 2015

Presentation information

Oral

Symbol S (Solid Earth Sciences) » S-CG Complex & General

[S-CG62] Slow earthquakes

Wed. May 27, 2015 4:15 PM - 6:00 PM 303 (3F)

Convener:*Hitoshi Hirose(Research Center for Urban Safety and Security, Kobe University), Kazushige Obara(Earthquake Research Institute, The University of Tokyo), Ryoko Nakata(Japan Agency for Marine-Earth Science and Technology), Chair:Tetsuya Takeda(National Research Institute for Earth Science and Disaster Prevention), Hitoshi Hirose(Research Center for Urban Safety and Security, Kobe University)

5:48 PM - 5:51 PM

[SCG62-P15] Modeling various slow slip events along the Hikurangi subduction zone

3-min talk in an oral session

*Bunichiro SHIBAZAKI1, Takanori MATSUZAWA2 (1.International Institute of Seismology and Earthquake Engineering, Building Research Institute, 2.National Research Institute for Earth Science and Disaster Prevention)

Keywords:modeling, slow slip events, Hikurangi subduction zone, a rate- and state-dependetn friction law, shallow short-term SSEs, Manuatsu long-term SSEs

Recent high-resolution seismic and geodetic observations have revealed the occurrence of slow slip events (SSEs) along various subduction plate interfaces. Long-term SSEs with a duration of 1.5 years (e.g., Manawatu SSEs) occur at the deeper portion (25--60 km) of the Hikurangi subduction zone, and shallow (5--15 km) SSEs with a duration of 1--3 weeks occur along the northern and central parts of the subduction zone. Wallace et al. (2012) reported a sequence of simultaneous short-term and long-term SSEs at the Hikurangi subduction zone during 2010--2011.
We modeled short-term and long-term SSEs along the Hikurangi subduction zone using a rate- and state-dependent friction law and considered realistic configurations of the plate interface. We set the coupling region where a-b is negative based on the study of interseismic coupling by Wallace et al. (2009). By setting the effective stress and the critical displacement of shallow short-term SSEs to approximately 1.5 MPa and 2.4 mm, respectively, we could reproduce SSEs with a duration of 1--3 weeks and recurrence interval of 3 years. Additionally, by setting the effective stress and the critical displacement of the Manuatsu long-term SSEs to approximately 3.0 MPa and 7.2 mm, respectively, we were able to reproduce SSEs with a duration of 0.5 years and recurrence interval of 5 years. The effective stress of the Manawatu SSE zone is two times larger than that of the short-term SSE zones. However, the ratio of the effective stress to the critical displacement of the Manawatu SSE zone is smaller than that of the short-term SSE zones. We could also reproduce a sequence of simultaneous short-term SSEs and a long-term Manawatu SSE as observed by Wallace et al. (2009). The occurrence of the various slow slip events suggests heterogeneous distributions of constitutive law parameters along the Hikurangi subduction zone.