[M-IS10] Interdisciplinary studies on pre-earthquake processes

[MIS10-02] A statistical approach to discover the location and focal mechanism role on possible seismo-ionospheric disturbances

★Invited Papers

*Dedalo Marchetti¹、Angelo De Santis²、Saioa A. Campuzano³、Kaiguang Zhu¹、Maurizio Soldani²、Serena D’Arcangelo^2,4、Martina Orlando²、Ting Wang¹、Gianfranco Cianchini²、Domenico Di Mauro²、Alessandro Ippolito²、Adriano Nardi²、Dario Sabbagh²、Wenqi Chen¹、Xiaodan He¹、Xuhui Shen⁵、Jiami Wen¹、Donghua Zhang¹、Hanshuo Zhang¹、Yiqun Zhang¹、Zeren Zhima⁵ (1.College of Instrumentation and Electrical Engineering, Jilin University, Changchun, 130061, China、2.Istituto Nazionale di Geofisica e Vulcanologia, Rome, 00143, Italy、3.Instituto de Geociencias IGEO (CSIC-UCM), Ciudad Universitaria, Madrid, 28040, Spain、4.Faculty of Physics, Complutense University of Madrid, Madrid, 28040, Spain、5.Space Observation Research Center, National Institute of Natural Hazards, MEMC, 100085, Beijing, China)

キーワード：earthquake, Swarm, focal mechanism, land/sea, geomagnetic field

In the last years, several works on satellite missions such as French satellite DEMETER and European Space Agency Swarm three-satellite constellation have found a statistical correlation between ionospheric disturbances and the following earthquakes. In particular, De Santis et al. (2019) explored for the first time the magnetic data from satellite in a possible relationship with the earthquakes. The authors investigated the ionospheric anomalies from Swarm three-satellite constellation magnetic and electron density data from January 2014 to August 2018 correlating with the M5.5+ shallow seismic events by a superposed epoch and space approach. The work demonstrated statistically not only that there were anomalies that preceded the earthquake with a probability that can reach more than two times the one obtained for random simulations but also that the anticipation time of the anomalies increased with the magnitude of the earthquake following the Rikitake (1987) empirical law.
Nowadays, the Swarm constellation is successfully in orbit from more than 8 years. In this work, an extended Worldwide Statistical Approach is proposed with such a large available dataset, using the same analysis technique of De Santis et al. (2019) and adding some new approaches as the investigation of the frequency of the magnetic and electron density signals along the orbits (about latitudinal profiles as Swarm is in quasi-polar orbit). The large available dataset permitted to confirm the previous results and found the concentration of anomalies for larger events such as M7.5+ (not well observed in De Santis et al., 2019 due to the data availability). Furthermore, we observed that the content of high frequency of the signal of the possible earthquake precursor anomalies becomes more intense as the earthquake is approaching. The huge amount of data permitted also to explore if the land or sea and focal mechanism (normal, reverse, or strike-slip) play a role in the frequency of the possible signal associated with the earthquakes. The focal mechanism has been found to have a weak influence on the frequency of the magnetic signal, while the sea earthquakes are more likely to be preceded by high-frequency magnetic signals than land earthquakes that are more likely preceded by slower magnetic disturbances.

References:
- De Santis, A., et al. (2019). Precursory worldwide signatures of earthquake occurrences on Swarm satellite data. Sci. Rep. https://doi.org/10.1038/s41598- 019-56599.
- Rikitake, T. (1987). Earthquake precursors in Japan: Precursor time and detectability. Tectonophysics, 136, 265–282. https://doi.org/10.1016/0040-1951(87)90029-1.