Abstract
In the paper, seismic strain field is considered as a variable of seismic activity. The strain field is calculated before the earthquake above <i>M</i>s7 in mainland China since 1980, and the abnormal change of time factor is extracted before the earthquake, by means of the natural orthogonal function expansion method. The results show that the time factor before the large earthquake will change suddenly, jump or jump down on stationary background. At least 3 typical fields will appear abnormal changes in the first 4 ones of seismic strain field before the earthquake, having the characteristics of multi-component display anomalies. The earliest time of abnormal occurrence is about 3 years before the earthquake. Moreover, there are some short-term time factor anomalies before some earthquakes. Through case studies the results of case studies show that the time factor anomaly extracted by strain field is more unique than seismic energy field in analyzing the anomaly of seismic activity. The difference between strain field and energy field is also discussed.
Highlights
It is well known that seismic activity is a random natural phenomenon
Yang [3] first applied the theory of natural orthogonal function to study the relationship between the time anomaly characteristics of the earthquake activity energy field in Ningxia region and the moderate earthquake in China
Yang [6] by using this method, the study found that 2008 Wenchuan county, Sichuan province area before an earthquake of magnitude Ms8.0 earthquake activity field and medium-term anomaly characteristics of time and space, and Wenchuan earthquake have good corresponding relation; Ma [7] by using this method, such as analysis of Yushu county of Qinghai province in 2010 before the magnitude Ms7.1 earthquake epicenter surrounding areas and along the Yushu fault zone seismic energy field of the time change, appears the first half of the anomalies of time and space, and the earthquake; Yang [8] by using this method, summarizes
Summary
It is well known that seismic activity is a random natural phenomenon. The purpose of seismicity research is to reveal the regularity of seismic activity, to explore the relationship between seismic anomalies and large earthquakes, and to seek solutions to earthquake forecast and prediction. Yang [3] first applied the theory of natural orthogonal function to study the relationship between the time anomaly characteristics of the earthquake activity energy field in Ningxia region and the moderate earthquake in China. Luo [4], the author used this method to the seismicity in Yunnan region of China, related research and systematic analysis of space-time field before and after the 1975 earthquake anomaly and the corresponding relation of medium-strong earthquakes; Luo [5] used this method to calculate the energy field of seismic activity in the northwest Yunnan to the southern Yunnan region of China extracted spatio-temporal anomaly, and predicted the strong earthquake of the region in the three years. Yang [6] by using this method, the study found that 2008 Wenchuan county, Sichuan province area before an earthquake of magnitude Ms8.0 earthquake activity field and medium-term anomaly characteristics of time and space, and Wenchuan earthquake have good corresponding relation; Ma [7] by using this method, such as analysis of Yushu county of Qinghai province in 2010 before the magnitude Ms7.1 earthquake epicenter surrounding areas and along the Yushu fault zone seismic energy field of the time change, appears the first half of the anomalies of time and space, and the earthquake; Yang [8] by using this method, summarizes
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
