Case 19: Deformation Precursors in the Mid-Term Stage at the Area Near the Epicenter of Strong Earthquakes
- Max Wyss
Published Online: 3 APR 2013
Copyright 1991 American Geophysical Union.
Evaluation of Proposed Earthquake Precursors
How to Cite
Duan, H.-C. (1991) Case 19: Deformation Precursors in the Mid-Term Stage at the Area Near the Epicenter of Strong Earthquakes, in Evaluation of Proposed Earthquake Precursors (ed M. Wyss), American Geophysical Union, Washington, D. C.. doi: 10.1029/SP032p0091
- Published Online: 3 APR 2013
- Published Print: 1 JAN 1991
Print ISBN: 9780875907840
Online ISBN: 9781118667873
- Earthquake prediction—Evaluation
Deformation precursors in the mid-term stage are clearly shown by numerically processed sea level data, in first order leveling data and in tilt crustal tide data respectively. One or two years before strong earthquakes the sea level changes near the epicenter appear to reach maximum values which are rarely attained during the recording history. One or two years before strong earthquakes the area near the epicenter shows obvious tilt tendency towards the epicenter with some strain feature and usually the first order elevation residues of benchmarks in basement rock are larger than their standard deviations by factors of 2 to 3. The amplitude variations of M 2 components computed in NS component data of crustal tides measured by tiltmeters at deformation acceleration stage in the observatories near the earthquake epicenter show an increasing tendency or systematic low values according to pressure stress or tensile stress acted upon observatory locations respectively. The appearances in the observatories located mainly in the direction of the P axis or the T axis are especially obvious. The computation results mentioned above could be confirmed with no exception by more than one observatory (station) or more than one event. However because of the limitation of data lengths the statistical precision couldn't be reliably estimated.