Abstract
A detailed gravity survey was carried out over the Ochi depression, the sothern part of the Noto peninsula in central Japan. The depression is supposed to have been formed by faulting or flexure of strata. An earthquake (Nanao earthquake M=6.0) occurred around it in 1933.Terrain corrected Bouguer anomalies are calculated assuming a mean density of 2.67g/cm3. The gravity system is based on IGSN 71. The distribution of gravity anomaly shows remarkably lower gravity anomaly of about 10 mgal within the depression.The analysis of gravity anomaly by using Talwani's two dimensional method clarifies that subsurface structure under the Ochi depression can be understood as a graben structure, as suggested by geological studies. Using geological evidence and available core sample data, the depth to the per-Tertiary basement is estimated to be more than 800m in southwest region and more than 400m in northeast one.
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Schedule a callMore From: Zisin (Journal of the Seismological Society of Japan. 2nd ser.)
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