Case 1: Precursory Quiescence and Recovery of Aftershock Activity Before Some Large Aftershocks
- Max Wyss
Published Online: 3 APR 2013
Copyright 1991 American Geophysical Union.
Evaluation of Proposed Earthquake Precursors
How to Cite
Matsu'ura, R.S. (1991) Case 1: Precursory Quiescence and Recovery of Aftershock Activity Before Some Large Aftershocks, in Evaluation of Proposed Earthquake Precursors (ed M. Wyss), American Geophysical Union, Washington, D. C.. doi: 10.1029/SP032p0008
- Published Online: 3 APR 2013
- Published Print: 1 JAN 1991
Print ISBN: 9780875907840
Online ISBN: 9781118667873
- Earthquake prediction—Evaluation
Temporal features of the aftershock activity following some large shallow earthquakes of M≥7 in Japan have been studied quantitatively. The earthquakes concerned were accompanied by large aftershocks which triggered their own aftershock activity. The purpose of the present study is to seek any anomalous change in aftershock activity of the main shock before the occurrence of such large aftershocks. Aftershock activity shows an appreciable decrease from the level expected from the modified Omori formula before the occurrence of a large aftershock. The aftershock activity then recovers to the normal level or even increases beyond the normal level shortly before the occurrence of the large aftershock. The recovered activity generally occurs near the hypocenter of the forthcoming large aftershock. Such a feature has been recognized ha fourteen cases out of eighteen for which sufficient data are available. We have the possibility of predicting the occurrence of a large aftershock which might be as large and disastrous as the main shock, if we keep watch on the change of the aftershock activity immediately following the main shock. Moreover, a rough prediction of the place can be made by checking the hypocenter location of aftershocks occurring in the recovered stage.