Bouguer Gravity Anomalies in the Fukuoka area, Kyushu,Japan.

Morijiri, Rie; Hiroshima, Toshio; Komazawa, Masao; Makino, Masahiko; Murata, Yoshinori; Nawa, Kazunari; Nishijima, Jun; Mogi, Toru

doi:10.9795/bullgsj.53.573

Cited by 4 publications

(3 citation statements)

References 2 publications

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“…The high-V p region is found just east of the earthquake fault. The Bouguer gravity anomaly in this region, which was reported by Morijiri et al (2002) and AIST (2005), shows a similarity to the spatial pattern of velocity perturbation. In the present study, the low-density anomaly corresponds to the low-velocity region, while.…”

Section: Discussion and Summarysupporting

confidence: 79%

Three-dimensional seismic velocity structure as determined by double-difference tomography in and around the focal area of the 2005 West off Fukuoka Prefecture earthquake

et al. 2006

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On March 20, 2005 the West off Fukuoka Prefecture earthquake (magnitude of 7.0 on the JMA scale) occurred in southeastern Japan. The earthquake fault was a left-lateral strike-slip having a nearly vertical fault plane and a strike in the WNW-ESE direction. The largest aftershock with a magnitude of 5.8 (JMA) followed 1 month later. To gain more detailed aftershock data, several teams from different Japanese universities jointly installed a number of temporary seismic stations and positioned Ocean Bottom Seismometers (OBSs) immediately above the focal area. Double-difference tomography was used to estimate the three-dimensional (3D) (Zhang and Thurber, 2003) velocity structures in and around the focal area based on the travel time data collected during seismic observations. The high-velocity regions estimated by the inversion are located on the edge of the aftershock area and on the shallow part of asperity, as inferred from the slip distribution. Conversely, the V p/V s ratio is not always as high as that found at the location of the asperity. This finding suggests that the construction of the medium is not uniformly elastic but complex, with different relations between elastic constants and strength.

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Section: Discussion and Summarysupporting

confidence: 79%

Three-dimensional seismic velocity structure as determined by double-difference tomography in and around the focal area of the 2005 West off Fukuoka Prefecture earthquake

et al. 2006

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“…Gravity data newly supplemented (a) for western Japan: 649 land gravity data taken from Morijiri et al [2002] and 924 marine data taken from Koizumi et al [1994], and (b) for Hokkaido: 5284 land gravity data provided by A. Yamamoto of Hokkaido University and 614 taken from Morijiri et al [2000].…”

Section: Supplementation Of Gravity Data In Gapsmentioning

confidence: 99%

“…Newer survey results have been reported in tabular form in their bulletins. We compiled two sets of point gravity data on land: 649 data for Fukuoka from Morijiri et al [2002], as shown in Figure 3a, and 614 data for eastern Hokkaido from Morijiri et al [2000], as shown in Figure 3b.…”

Section: Supplementation Of Gravity Data In Gapsmentioning

confidence: 99%

Wavelet approach to improvement of gravity field–geoid modeling for Japan

Kuroishi

Keller

2005

J. Geophys. Res.

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[1] An improved gravimetric geoid model for Japan, JGEOID2004, on a grid of 1 Â 1.5 minutes, was constructed by the one-dimensional fast Fourier transform method with EGM96 as a foundation model. The model geoid heights in the nontidal system refer to the GRS80 ellipsoid aligned in the ITRF94 (epoch 1997.0). Newly acquired terrestrial gravity data supplemented the data gaps of the previous model, JGEOID2000. A ''semidiscrete'' wavelet analysis/reconstruction with two-dimensional (2-D) Halo wavelets were developed and successfully applied to a combination of marine gravity data and an altimetric gravity model, KMS02. The method is used to localize 2-D signal components in the spatio-frequency domain and to screen them as a locally adjustable band-pass filter. Compared with 816 GPS/leveling benchmarks, JGEOID2004 showed significant improvement over JGEOID2000: the standard deviation of the differences from the best fit planes is reduced from 15.3 cm to 9.2 cm. Substantial localized errors, which are due to systematic errors of the marine gravity data as well as to data gaps on land and in the inland sea, were effectively removed.Citation: Kuroishi, Y., and W. Keller (2005), Wavelet approach to improvement of gravity field -geoid modeling for Japan,

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Geology of the Paleogene Miike Coalfield in the Ariake Sea Area and Its Litho-biostratigraphic Correlation with Paleogene Coalfields in Northwestern Kyushu, Japan

Iguchi

2016

Journal of Geography(Chigaku Zasshi)

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The litho-biostratigraphy of Paleogene coalfields in northwestern Kyushu, Japan is reviewed on the basis of data obtained from the Miike Coalfield below the Ariake Sea. The Miike Coalfield extends over a wide area below the Ariake Sea as far as the west coast. The Paleogene stratigraphy of the coalfield is currently defined as the Ginsui Formation and the Ohmuta and Manda Groups in ascending order. The Manda Group consists of the Kattachi and Yotsuyama Formations in ascending order. The Kattachi Formation contains large quantities of glauconite in the basal part, the base of which has been defined as the base of the marine Manda Group. However, the Kattachi Formation contains coal seams and varies laterally, with glauconite content decreasing westerly. No significant facies variation with the underlying Ohmuta Group can be seen. The Kattachi Formation is, therefore, re-interpreted as the uppermost zone of the underlying coal-bearing Ohmuta Group. Glauconite sandstone of the basal part of the Yotsuyama Formation overlies underlying strata with a clear boundary throughout the coalfield. No significant facies variation exists in the Ohmuta Group. As a result, the Paleogene stratigraphy of the Miike Coalfield is revised into the Ginsui, Miike and Yotsuyama Formations in ascending order. The marine Yotsuyama Formation reaching ca. 800m in thickness below the Ariake Sea is divided into four lithostratigraphic members: Ia （glauconite sandstone） , Ib （shale） , IIa （glauconite sandstone） , and IIb （shale） Members in ascending order. The Yotsuyama Formation spans the late Middle Eocene （Subzone CP14a of Okada and Bukry, 1980） to the late Late Eocene （Subzone CP15b） age. Marine sequence, biostratigraphically correlative with Ia to IIb Members, is distributed in the Takashima and Amakusa Coalfields, while marine strata correlative with IIb Member are distributed in the Sakito-Mastushima and Isahaya Coalfields. These facts indicate that marine transgression occurred from the south and that a marine environment prevailed in northwestern Kyushu in the late Middle to late Late Eocene and peaked during the Yotsuyama Formation deposition.

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Bouguer Gravity Anomalies in the Fukuoka area, Kyushu,Japan.

Cited by 4 publications

References 2 publications

Three-dimensional seismic velocity structure as determined by double-difference tomography in and around the focal area of the 2005 West off Fukuoka Prefecture earthquake

Three-dimensional seismic velocity structure as determined by double-difference tomography in and around the focal area of the 2005 West off Fukuoka Prefecture earthquake

Wavelet approach to improvement of gravity field–geoid modeling for Japan

Geology of the Paleogene Miike Coalfield in the Ariake Sea Area and Its Litho-biostratigraphic Correlation with Paleogene Coalfields in Northwestern Kyushu, Japan

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