Exploration Geophysics Exploration Geophysics Society
Journal of the Australian Society of Exploration Geophysicists
RESEARCH ARTICLE

Three-dimensional gravity inversion using automatic regional-residual components separation with application to the Iwaki area in Fukushima Prefecture, Japan

Yasuaki Murata
+ Author Affiliations
- Author Affiliations

Fukushima Renewable Energy Institute, AIST (FREA), 2-2-9 Machiikedai, Koriyama, Fukushima 963-0298, Japan. Email: murata.gsj@aist.go.jp

Exploration Geophysics - https://doi.org/10.1071/EG17085
Submitted: 26 June 2017  Accepted: 5 July 2017   Published online: 12 September 2017
Originally submitted to SEGJ 10 May 2016, accepted 4 April 2017  

Abstract

We have developed a simple method for analysing gravity data to define 3D subsurface structures consistent with geological maps and reflection seismic survey results. This new method makes it possible to automatically separate gravity anomalies caused by structures that are the target of analysis (residual gravity) and not subject to gravity anomaly analysis (trend surfaces or regional gravity variations). This separation is achieved by assuming that the gravity anomaly trend surface is extremely smooth prior to analysis. In addition, this analysis can be carried out automatically, so it is possible to use a boot-strap simulation to evaluate the effect that gravity data accuracy and survey point distribution have on the analysis results. Using this newly developed method, we conducted a 3D subsurface structural analysis based on newly obtained gravity survey data in an area around Iwaki City, Fukushima Prefecture. The results of the 3D structural analysis revealed sharp depressions in the basement rock and basin-shaped underground structures along the Yunodake and Yamada faults. Finally, we were able to estimate the influence of survey point distribution and abrupt changes in the structure on the analysis results using a boot-strap simulation of the 3D analysis.

Key words: three-dimensional structure, boot-strap simulation, Fukushima Prefecture, gravity survey, Idosawa Fault, Iwaki City, regional-residual separation, Yunodake Fault.


References

Awata, Y., Kagohara, K., Sugiyama, Y., Yoshioka, T., Azuma, T., Ando, K., and Maruyama, T., 2011, Slip vectors of the surface faulting along the Yunotake and Fujiwara faults associated with the earthquake of April 11, 2011, SE Fukushima Prefecture: Report of Coordinating Committee for Earthquake Prediction, 86, 170–172.

Cordell, L., and Henderson, R. G., 1968, Iterative three-dimensional solution of gravity anomaly data using a digital computer: Geophysics, 33, 596–601
Iterative three-dimensional solution of gravity anomaly data using a digital computer:CrossRef |

Geological Survey of Japan (eds.) 1957, Geological map and explanatory text of the Joban Coal Field: Geological maps of coal fields of Japan, 1, Geological Survey of Japan, AIST.

Geological Survey of Japan (eds.) 2013, Gravity database of Japan, DVD edition: Digital geoscience map, P-2, Geological Survey of Japan, AIST.

Inoue, H., 1986, A least-squares smooth fitting for irregularly spaced data: finite-element approach using the cubic B-spline basis: Geophysics, 51, 2051–2066
A least-squares smooth fitting for irregularly spaced data: finite-element approach using the cubic B-spline basis:CrossRef |

Komazawa, M., 1995, Gravimetric analysis of Aso volcano and its interpretation: Journal of the Geodetic Society of Japan, 41, 17–45
Gravimetric analysis of Aso volcano and its interpretation:CrossRef |

Kubo, K., Yanagisawa, Y., Yamamoto, T., Nakae, S., Takahashi, H., Toshimitsu, S., Banno, Y., Miyachi, Y., Takahashi, M., Komazawa, M., and Ohno, T., 2007, Geological map of Japan 1 : 200,000, Shirakawa: Geological Survey of Japan, AIST.

Li, Y., and Oldenburg, D. W., 1998, Separation of regional and residual magnetic field data: Geophysics, 63, 431–439
Separation of regional and residual magnetic field data:CrossRef |

Mickus, K. L., Aiken, C. L. V., and Kennedy, W. D., 1991, Regional-residual gravity anomaly separation using the minimum-curvature technique: Geophysics, 56, 279–283
Regional-residual gravity anomaly separation using the minimum-curvature technique:CrossRef |

Murata, Y., 1993, Estimation of optimum average surficial density from gravity data: an objective Bayesian Approach: Journal of Geophysical Research, 98, 12097–12109
Estimation of optimum average surficial density from gravity data: an objective Bayesian Approach:CrossRef |

Murata, Y., and Noro, H., 1993, Optimization of estimation procedure of Bouguer density by use of the ABIC-minimization method: Butsuri Tansa (Geophysical Exploration), 46, 120–127

Murata, Y., Matsumoto, N., Okada, C., and Takahashi, Y., 2013, Gravity survey data of Iwaki Area, Fukushima Prefecture: AIST Open-File Report, no. 585, 74 pp., 1 CD-ROM, Geological Survey of Japan, AIST.

Nagihara, S., and Hall, S. A., 2001, Three-dimensional gravity inversion using simulated annealing: Constraints on the diapiric roots of allochthonous salt structures: Geophysics, 66, 1438–1449
Three-dimensional gravity inversion using simulated annealing: Constraints on the diapiric roots of allochthonous salt structures:CrossRef |

Nawa, K., Fukao, Y., Shichi, R., and Murata, Y., 1997, Inversion of gravity data to determine the terrain density distribution in southwest Japan: Journal of Geophysical Research, 102, 27703–27719
Inversion of gravity data to determine the terrain density distribution in southwest Japan:CrossRef |

Nettleton, L. L., 1976, Gravity and magnetics in oil prospecting: McGraw-Hill.

Suda, Y., Murata, Y., Kikuchi, T., and Hanaoka, N., 1991, Physical Properties Data-Base System of Rocks (PROCK): GSJ Open-File Report, no.155, 231 pp., Geological Survey of Japan, AIST.

Tsutsumi, H., and Toda, S., 2012, Surface rupture associated with the April 11, 2011 Fukushima-ken Hamadori earthquake and paleoseismic history of the causative fault: Journal of the Geological Society of Japan, 118, 559–570
Surface rupture associated with the April 11, 2011 Fukushima-ken Hamadori earthquake and paleoseismic history of the causative fault:CrossRef |

Uchida, T., and Ueda, T., 2013, Electromagnetic survey over Yunodake and Itozawa Faults in Iwaki area, Fukushima Prefecture, Reports of Research and Investigation on Multiple Geological Hazards Caused by Huge Earthquakes: GSJ Interim Report, no. 66, 103–112.

Yamaguchi, K., Ito, S., and Kano N., 2013, Integrated seismic survey of reflection and refraction method in Iwaki area, Fukushima Prefecture, Reports of Research and Investigation on Multiple Geological Hazards Caused by Huge Earthquakes: GSJ Interim Report, no. 66, 83–102.



Export Citation