Author:
Luo Guofu,Ding Fenghe,Ma Heqing,Yang Mingzhi
Abstract
In this study, natural orthogonal expansion was performed on earthquake frequencies to compute the pre-quake frequency fields of 9 Ms ≥7.0 earthquakes in mainland China from 1980 to 2020. The temporal and spatial pre-quake anomalies of these earthquakes were extracted from their frequency fields. We found that the majority of pre-quake temporal anomalies (i.e., variations exceeding two-times the absolute mean square error) of a strong earthquake are condensed within the first four frequency fields, and typically comprise multiple components. The temporal factor of the first frequency field usually accounts for the largest proportion of these anomalies (40%–60% of the entire field). Most Ms ≥7.0 earthquakes exhibited long-term anomalies 5–8 years before their occurrence; some presented medium-term anomalies 1–2 years prior to the quake, and only a few presented short-term and imminent anomalies (≤3 months before the quake). Anomalous seismic hazard zones have high-gradient turning points in regional frequency-field contour maps, and the epicenters of strong earthquakes are often located in areas containing active faults that have contour values. Through the comparison of seismic frequency field and the traditional method of regional seismic activity frequency (3 months), it is shown that the frequency-field time factor has the advantages of diversified and rich abnormal information. The slope comparison between the frequency field and the cumulative frequency curve shows that the frequency anomaly time of the two is consistent, and the conclusion is reliable. Therefore, the seismic frequency method can predict the occurrence time and location of strong earthquakes, which is closer to the predictable seismic model.
Subject
General Earth and Planetary Sciences
Reference30 articles.
1. Statistical analysis of the preparatory phase of the MW 8.1 Iquique earthquake, Chile;Aden-Antóniow;JGR Solid Earth,2020
2. Anomaly of small earthquake activities before medium to strong earthquakes in the northeast margin of the Qinhai-Tibe block;Feng;Earthq. (in Chin.,2009
3. Combining swarm Langmuir probe observations, LEO-POD-based and ground-based GNSS receivers and ionosondes for prompt detection of ionospheric earthquake and tsunami signatures: Case study of 2015 Chile-Illapel event;Jarmolowski;J. Space Weather Space Clim.,2021
4. A long-term seismic quiescence started 23 years before the 2011 off the Pacific coast of Tohoku earthquake (M=9.0);Katsumata;Earth Planets Space,2011
5. Enhancement of seismicity recorded by the Qiaojia seismic network before the 2013 Lushan and 2014 Ludian earthquakes;Li;Earthq. (in Chin.,2017
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