Case 4: Anomalous Strain Prior to the 1923 Kanto, Japan, Earthquake as Deduced from Analysis of Old Triangulation Data
- Max Wyss
Published Online: 3 APR 2013
Copyright 1991 American Geophysical Union.
Evaluation of Proposed Earthquake Precursors
How to Cite
Fujii, Y. and Nakane, K. (1991) Case 4: Anomalous Strain Prior to the 1923 Kanto, Japan, Earthquake as Deduced from Analysis of Old Triangulation Data, in Evaluation of Proposed Earthquake Precursors (ed M. Wyss), American Geophysical Union, Washington, D. C.. doi: 10.1029/SP032p0021
- Published Online: 3 APR 2013
- Published Print: 1 JAN 1991
Print ISBN: 9780875907840
Online ISBN: 9781118667873
- Earthquake prediction—Evaluation
Horizontal earth's strains preceding the Kanto, Japan, earthquake of 1 September 1923, are deduced from the analysis of the old triangulation data. The anomalous strains that are several times larger than usual tectonic strain are found in the westem part of Tokyo Bay, Sagamihara district, Japan for the observational period 1882/91–1898/1910, while any significant strain is not revealed in the other region of the Kanto district. The Kanto district was surveyed twice during the period 1883/85–1890/92 in the west and during the period 1890/92–1897/99 in the east respectively. The polarity of the detected anomalous strains, the directions and the signs of the principal strains, are quite the same as those of the postseismic crustal strains during the period 1924–74, and are reversed as compared to the coseismic one.
The Philippine Sea plate thrusts under the South Kanto district with N25°W direction and pulls down the land during the interseismic period. The aseismic reverse faulting would begin several decades before the 1923 Kanto earthquake along the deep interface between the Asian plate and the convergent Philippine Sea plate. The down-going along the locked part of the interface would be accelerated, thus the compressional stress on the earth's surface might be concentrated over the deep fault plane together with the acceleration of the subsidence at the tip of the peninsula close to the Sagami trough.