Source-Rupture Process of the 2007 Noto Hanto, Japan, Earthquake Estimated by the Joint Inversion of Strong Motion and GPS Data

Abstract

The source-rupture process during the 2007 Noto Hanto earthquake, which was a reverse-faulting event located near the western coast of the Noto peninsula in central Japan, was estimated by the kinematic linear waveform inversion method. The waveform inversion was conducted by jointly using velocity waveforms recorded at 12 near-source strong-motion stations and static horizontal displacements recorded at 19 Global Positioning System (GPS) stations. In order to implement reliable Green's functions into the inversion, a one-dimensional underground velocity structure for each individual strong-motion station was modeled through waveform modeling of an aftershock. The waveform inversion result showed the following image of the source-rupture process. The larger slip concentrated in the vicinity of the hypocenter, and it extended to the shallow portion of the source fault with a maximum slip of 5.1 m. The whole source process was characterized by the total seismic moment of 1:57 × 10 19 N•m (M w 6.7) with the rupture duration of approximately 9 s. The obtained source model explained observed strong ground motions and GPSmeasured static horizontal displacements well. The slip distribution correlated well with the spatiotemporal aftershock distribution, and the northeast end of the rupture was blocked by the resistive structure in the crust. From these facts, the 2007 Noto Hanto earthquake could be concluded as reactivation of preexisting seafloor active faults, F14 and F15, which were reported by the previous geophysical and geological surveys off the shore of the Noto peninsula.

Remote triggering of seismicity at Japanese volcanoes following the 2016 M7.3 Kumamoto earthquake

“…The remote events clearly occur during the maximum phases of both the Love (transverse velocity component) and Rayleigh waves (vertical and radial velocity waveform components); however, it is difficult to judge which of the two is mostly responsible for the triggering. The remote triggering in Noto occurred likely on an active fault, close to the epicenter of a past large earthquake, the 2007 M6.9 Noto earthquake (e.g., Asano and Iwata 2011). Figure 3b shows the triggering close to the AkitaKomagatake volcano (epicentral distance of 1168 km from the mainshock), which is one of the active volcanoes in northern Honshu.…”

Rupture model of the 2011 Mineral, Virginia, earthquake from teleseismic and regional waveforms

“…[3] We invert teleseismic P waveforms and regional and local crustal P and S waveforms in two independent inversions to examine the robustness of the slip distribution. Joint inversions of different data sets have become common practice in finite fault studies [Delouis et al, 2002;Rhie et al, 2007;Asano and Iwata, 2011;Hartzell et al, 2013;Kubo and Kakehi, 2013] and can be a powerful tool to constrain complex faulting or to more accurately resolve slip when one data set is limited. But a joint inversion is also a weighted compromise between the solutions from individual data sets.…”

Relationship between coseismic slip and static stress drop of similar aftershocks of the 2007 Noto Hanto earthquake

“…4c). Following the definition of Horikawa (2008), we define here a large slip area as being an area with a slip ≥1 m and a small slip area as an area with a slip <1 m. For the 2007 Noto Hanto earthquake, as mentioned in the "Introduction" subsection, several slip models have reported a common feature of slip distribution: that is, a large coseismic slip area exists on the fault plane in the shallower part from the hypocenter based on different kinds of data (Fukushima et al 2008;Ozawa et al 2008;Asano and Iwata 2007). The absolute values of slip are slightly different between these models, but the pattern of the slip distribution is similar: in other words, the relationship between the slip and the static stress drop approximately holds in spite of the absolute value of the slip, implying that the choice of the slip model does not affect the following discussion.…”

“…1), accompanied by uplift and subsidence along the coastline around the source area (Hiramatsu et al 2008). Several heterogeneous slip models have been proposed for the 2007 Noto Hanto earthquake based on strong motion data (Horikawa 2008), the coseismic crustal movement (Fukushima et al 2008;Ozawa et al 2008), and both of these (Asano and Iwata 2007). These models showed that a large coseismic slip area existed from the hypocenter to the shallow part of the fault plane.…”