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Caldera structure inferred from gravity anomalies west of Nagamachi-Rifu Fault, Northeast Japan

Abstract

A gravity survey was conducted in and around the Nagamachi-Rifu Fault. The density for both terrain and Bouguer corrections was chosen to be 2,300 kg/m3, because volcanic rocks are dominant over the whole measurement area and the surface layer density is estimated to be low from geological considerations. The Bouguer anomalies are characterized by a low anomaly similar to those of a caldera and the basement structure inferred from two and three-dimensional analysis shows that the depth is often more than 1 km in the caldera region and that there is a circular structure. The gradient of basement is steepest at the southern margin, and it resembles to rim of funnel-shaped caldera.

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Correspondence to Masao Komazawa.

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Komazawa, M., Mishina, M. Caldera structure inferred from gravity anomalies west of Nagamachi-Rifu Fault, Northeast Japan. Earth Planet Sp 54, 1049–1053 (2002). https://doi.org/10.1186/BF03353300

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Keywords

  • Gravity Anomaly
  • Bouguer Anomaly
  • Gravity Survey
  • Terrain Correction
  • Geographical Survey Institute