Estimation of crustal structure in central and west Japan from waveform modeling of regionalPL waves

Fujita, Masayuki; Nishimura, Keiichi

doi:10.1007/bf00876577

Cited by 7 publications

(5 citation statements)

References 12 publications

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“…Furthermore, the long period body waves (e.g. PL) are not fully developed at the epicentral ranges considered in this study (Holt & Wallace 1990;Fujita & Nishimura 1993). Thus, the 0.1-0.4 Hz and 0.04-0.1 Hz passbands were applied only to the P nl and surface wave segments, respectively.…”

Section: Frequency Bandsmentioning

confidence: 99%

“…Seismic waveforms are alternative materials to estimate velocity structure that mitigate non‐uniqueness because these waveforms contain more information than arrival times. Linearized techniques have been widely adopted in various studies of waveform inversion (Mellman 1980; Woodhouse & Dziewonski 1984; Holt & Wallace 1990; Fujita & Nishimura 1993; Mégnin & Romanowicz 2000; Zhu et al 2006; Takeuchi 2007; Tape et al 2009; Fichtner et al 2010). However, avoiding local minima has often failed when the non‐linearity is severe between waveforms and earth structures (Snieder 1998; Sambridge 2001).…”

Section: Introductionmentioning

confidence: 99%

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Forward waveform modelling procedure for 1-D crustal velocity structure and its application to the southern Korean Peninsula

Kim¹,

Rhie²,

Kim

2011

Geophysical Journal International

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S U M M A R YWe propose a full-grid search procedure for broad-band waveform modelling to determine a 1-D crustal velocity model. The velocity model can be more constrained because of the use of broad-band waveforms instead of traveltimes for the crustal phases, although only a small number of event-station pairs were employed. Despite the time-consuming nature of the full-grid search method to search the whole model parameter space, the use of an empirical relationship between the P-and S-wave velocities can significantly reduce computation time. The proposed method was applied to a case in the southern Korean Peninsula. Broad-band waveforms obtained from two inland earthquakes that occurred on 2007 January 20 (M w 4.6) and 2004 April 26 (M w 3.6) were used to test the method. The three-layers over halfspace crustal velocity model of the P-and S-wave velocities was estimated. Comparisons of waveform fitness between the final model and previously published models demonstrate advancements in the average value of waveform fitness for the inland earthquakes. In addition, 1-D velocity models were determined for three distinct tectonic regions, namely, the Gyonggi Massif, the Okcheon Belt and the Gyeongsang Basin, which are all located inside the study area. A comparison between the three models demonstrates that the crustal thickness of the southern Korean Peninsula increases from NW to SE and that the lower crustal composition of the Okcheon belt differs from that of the other tectonic regions.

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Section: Frequency Bandsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Forward waveform modelling procedure for 1-D crustal velocity structure and its application to the southern Korean Peninsula

Kim¹,

Rhie²,

Kim

2011

Geophysical Journal International

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“…This average velocity model would improve the waveform fits for the azimuth for which we have the most complete regional seismic data in 1944. We compare the performance of the UMJ model with the P nl velocity model (Table 2b) estimated by Fujita and Nishimura [1991, 1993] using group velocities of P nl waves along ray paths crossing central Honshu. Figure 6 shows synthetics generated from both models compared with the observations for two recent events, E1 and E2 (Table 1), recorded at station UMJ.…”

Section: Velocity Models and Green's Function Calibrationmentioning

confidence: 99%

Rupture process of the 1944 Tonankai earthquake (M_s 8.1) from the inversion of teleseismic and regional seismograms

Ichinose¹,

Thio²,

Somerville³

et al. 2003

J. Geophys. Res.

126

134

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[1] We digitized teleseismic and regional records of the 1944 Tonankai earthquake. We used the multiple time window method to invert these records for the spatial and temporal distribution of slip and rake. We assume a 220 Â 140 km fault with a spacing of 20 Â 20 km and a maximum rupture velocity of 2.5 km/s. The inversion resolved an asperity along the accretionary wedge and under the Shima and Atsumi Peninsulas. The rupture propagated from southwest to northeast, and there was little slip near the hypocenter, consistent with the absence of uplift in the overlying submarine forearc basin. The peak slip is 2.3 m, and the total seismic moment is 2.4 Â 10 28 dyn cm (M w 8.2). We compared the predicted and observed vertical geodetic displacements and inferred that the limit of rupture is consistent with the change from subsidence to uplift west of the Atsumi Peninsula. This suggested that the earthquake did not rupture the plate interface in the Tokai gap. We modeled the tsunami using sea-bottom displacements generated from this slip model. The tide gauge amplitudes and frequency content are consistent with those predicted. Resolution tests from inverting synthetic seismograms computed using a simplified slip model indicated that the combination of teleseismic and regional data sets best recovers the asperity locations and peak slips given similar station geometry and degrees of freedom. An inversion of the synthetic regional data set indicates that slip artifacts can occur early in the rupture process due to many clipped records while the inversion of synthetic teleseismic data set had less resolution and recovered only 50% of the peak slip.

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“…(left) Comparison between the initial S wave velocity model and velocity models for paths between F‐net stations at the 1948 Fukui, 1944 Tonankai, and 1943 Tottori earthquakes. Also shown is the P nl model [ Fujita and Nishimura , 1991, 1993] and Fukui model used by Kikuchi et al [1999]. (right) Iterative waveform inversion misfit versus iteration curves.…”

Section: Velocity Models and Green's Function Calibrationmentioning

confidence: 99%

Rupture process of the 1948 Fukui earthquake (M 7.1) from the joint inversion of seismic waveform and geodetic data

Ichinose¹

2005

J. Geophys. Res.

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[1] We used teleseismic body waves, regional low-gain strong motion seismograms, and horizontal geodetic displacements from triangulation surveys to invert for the slip distribution of the 1948 Fukui, Japan, earthquake using the multiple time window method. The earthquake ruptured unilaterally from a depth of 10 km to the north with very little slip (0-0.5 m) evenly distributed across a fault of 24 by 18 km over a period of about 10 s. At 9 s after the initiation of rupture, an adjacent fault along the same strike ruptured to the south from the hypocenter to about 20-30 km toward Fukui city mostly along a shallow asperity between 0 and 12 km depth. The large amount of shallow slip (1-1.5 m) below and within the sedimentary basin and strong rupture directivity likely contributed to the high amount of damage in Fukui city. We obtain a total seismic moment of 1.6-2.2 Â 10 26 dyn cm (M w 6.74-6.84) which is similar to results by Kanamori (1973), Sagiya (1999), and Kikuchi et al. (1999) using portions of the same regional strong motion and geodetic data sets. We needed to use very low rupture velocities (1.5 km/s) and a hypocenter 10-20 km north of the original location to fit the combined geodetic and seismic data sets with a single fault model. We developed an alternative fault model with two segments allowing for different rupture dynamics for each segment. This resulted in a slightly better fit to the data and allows for a more reasonable rupture velocity up to 2.4 km/s. Citation: Ichinose, G. A., P. Somerville, H. K. Thio, S. Matsushima, and T. Sato (2005), Rupture process of the 1948 Fukui earthquake (M 7.1) from the joint inversion of seismic waveform and geodetic data,

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Estimation of crustal structure in central and west Japan from waveform modeling of regionalPL waves

Cited by 7 publications

References 12 publications

Forward waveform modelling procedure for 1-D crustal velocity structure and its application to the southern Korean Peninsula

Forward waveform modelling procedure for 1-D crustal velocity structure and its application to the southern Korean Peninsula

Rupture process of the 1944 Tonankai earthquake (M_s 8.1) from the inversion of teleseismic and regional seismograms

Rupture process of the 1948 Fukui earthquake (M 7.1) from the joint inversion of seismic waveform and geodetic data

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Estimation of crustal structure in central and west Japan from waveform modeling of regionalPL waves

Cited by 7 publications

References 12 publications

Forward waveform modelling procedure for 1-D crustal velocity structure and its application to the southern Korean Peninsula

Forward waveform modelling procedure for 1-D crustal velocity structure and its application to the southern Korean Peninsula

Rupture process of the 1944 Tonankai earthquake (Ms 8.1) from the inversion of teleseismic and regional seismograms

Rupture process of the 1948 Fukui earthquake (M 7.1) from the joint inversion of seismic waveform and geodetic data

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Rupture process of the 1944 Tonankai earthquake (M_s 8.1) from the inversion of teleseismic and regional seismograms