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A method to estimate the maximum stress time in a fault zone before an earthquake

Amiri Khamkani Hossein, Tavakoli Chatroodi Mohammad Reza, Bahrampour Alireza

Acta Geophysica

2021

Vol. 69, no. 6

2145--2159

On the basis of Coulomb criterion and Anderson theory of faulting, a method for estimating the time of maximum shear stress of a failure after an earthquake is proposed in this paper. After the earthquake and in the strain recovery time interval, the second derivative of shear stress versus time is positive and approaches to a turning point. After the turning point by employing the curve fitting and extrapolation by an optimal polynomial, the maximum shear stress and its corresponding time can be estimated. In the proposed method, the real-time variation of stress, distributed at any point along the fault, can be measured by a distributed optical fiber stress sensor. The method is verified in the theoretical framework and experimental data prior to 2011 Tohoku (Japan) and 2014 Alaska earthquakes. The proposed method is statistically investigated according to the data of successive earthquakes of M ≥ 5 in Parkfeld, Kuhbanan, and Golbaf–Sirch faults. The predicted time is in good agreement with the experimental results. Consequently on the basis of real-time measurements, a time-predictable model is proposed.

Application of the time-predictable model in Peninsular India for future seismic hazard assessment

Shanker D., Singh H. N.

Acta Geophysica

2007

Vol. 55, no. 3

302-312

It has been the belief among Earth scientists that the Peninsular Shield is aseismic, as the region attained stability long ago. However, the earthquake at Koyna (10 December 1967), Bhadrachalam (13 April 1969), Broach (23 March 1970), Hyderabad (30 June 1983), Khillari (30 September 1993), Jabalpur (22 May 1997), Gujarat (26 January 2001), and additional ones of smaller magnitudes, altered this concept. This area has experienced many widely distributed shallow earthquakes, some of them having large magnitudes. It is now widely accepted that seismic activity still continues with moderate events. Therefore, a need has arisen to take into consideration recent seismological data to assess the future seismic status of Peninsular India. Earthquake generation model has been studied to develop the statistical relations with surface wave magnitude (MS ≥ 4.5). Five seismogenic sources showing clustering of earthquakes and including at least three main shocks of magnitude 4.5 ≤ MS ≤6.5 giving two repeat times, have been identified. It is mainly based on the so-called "regional time-predictable model". For the consid-ered region it is observed that the time interval between two consecutive main shocks depends on the preceding main shock magnitude (Mp) not on the following main shocks magnitude Mf suggesting the validity of time predictable model in the region.