Postseismic deformation following the 2005 West Off Fukuoka Prefecture Earthquake (M7.0) derived by GPS observation

Abstract

We constructed a temporary GPS network around the aftershock area of the 2005 West Off Fukuoka Prefecture Earthquake (M7.0) in order to investigate the characteristics of its postseismic deformation. Our GPS network data, as well as the GEONET data, were analyzed using Bernese GPS software. We detected notable postseismic deformation in horizontal components close to the fault plane. The observed maximum displacement was 5.6 cm at the GNKI site on Genkaijima Island. A logarithmic law was adapted to the coordinate time series data, revealing decay times from 2 to 23 days, similar to those obtained for the 2003 Tokachi-oki Earthquake (M8.0). The amount of postseismic slips on the fault was assessed using the coseismic fault model proposed by the Geographical Survey Institute (GSI). We derived an optimum fault model of postseismic slip on the shallow (less than 3 km depth) portion of the fault. Our findings indicate that postseismic slip occurred only in shallow parts of the coseismic fault.

Aftershock seismicity and fault structure of the 2005 West Off Fukuoka Prefecture Earthquake (MJMA7.0) derived from urgent joint observations

“…We installed ten GPS receivers around the aftershock region, and analyzed our GPS data together with the GEONET data of the Geographical Survey Institute (GSI), Japan. The results of the GPS observation are reported by Nakao et al (2006).…”

Postseismic displacements following the 2007 Noto peninsula earthquake detected by dense GPS observation

“…Kato et al, 1997;Nakano and Hirahara, 1997;Sagiya et al, 2002;Takahashi et al, 2005;Sagiya et al, 2005;Nakao et al, 2006). The observed postseismic displacements following these earthquakes have a tendency to decay rapidly, although the assumed mechanisms were different among these studies.…”

“…The observed postseismic displacements following these earthquakes have a tendency to decay rapidly, although the assumed mechanisms were different among these studies. Takahashi et al (2005) and Nakao et al (2006) used a logarithmic decaying function and obtained short decay time of 0.03-10.30 days for the 2004 mid-Niigata earthquake and 2-23 days for the 2005 Fukuoka earthquake, respectively. Our result also gives similar characteristics, which suggests that there should be similar conditions in the crust beneath the Japanese islands.…”

“…Sagiya et al (2005) suggest a shallow afterslip for the mid-Niigata prefecture earthquake. Nakao et al (2006) also obtained afterslip on the shallow portion of the source fault for the 2005 Fukuoka earthquake. We also obtained a shallow afterslip for the Noto peninsula earthquake.…”

High resolutionQ−1estimation based on extension of coda normalization method and its application toP-wave attenuation structure in the aftershock area of the 2005 West Off Fukuoka Prefecture Earthquake (M7.0)

“…The post‐seismic slip occurring on the earthquake faults was also not spatially uniform (e.g. Nakao et al 2006). The post‐seismic slip is possibly related to the relaxation in the medium having an anelastic property.…”