Abstract
The current status of ionospheric precursor studies associated with large earthquakes (EQ) is summarized in this report. It is a joint endeavor of the “Ionosphere Precursor Study Task Group,” which was formed with the support of the Mitsubishi Foundation in 2014–2015. The group promotes the study of ionosphere precursors (IP) to EQs and aims to prepare for a future EQ dedicated satellite constellation, which is essential to obtain the global morphology of IPs and hence demonstrate whether the ionosphere can be used for short-term EQ predictions. Following a review of the recent IP studies, the problems and specific research areas that emerged from the one-year project are described. Planned or launched satellite missions dedicated (or suitable) for EQ studies are also mentioned.
Highlights
Anomalous behavior before large earthquakes (EQs) has been reported in several geophysical parameters, for example, VLF propagation (Hayakawa et al 2010), infrared emission (Ouzounov and Freund 2004), and particle precipitation (Aleksandrin et al 2003; Sgrigna et al 2006), the existence of particle precipitation triggered by VLF waves associated with such EQs is controversial
Statistics on the total electron content (TEC) modification During our project period, statistics on the possible ionosphere disturbance before large earthquake were conducted for 157 EQs with M > 6 that occurred in Japan from January 1998 to February 2015 using both NmF2 and TEC data
While we prepare for such a near future satellite mission, further analysis of the existing data acquired from available satellites such as Defense Meteorological Satellite Program (DMSP), CHAMP, Formosat-3/ COSMIC, and Formosat-1 (ROCSAT-1) should be continued
Summary
Anomalous behavior before large earthquakes (EQs) has been reported in several geophysical parameters, for example, VLF propagation (Hayakawa et al 2010), infrared emission (Ouzounov and Freund 2004), and particle precipitation (Aleksandrin et al 2003; Sgrigna et al 2006), the existence of particle precipitation triggered by VLF waves associated with such EQs is controversial. Among EQ-related precursor phenomena, the effects of large EQs on the ionosphere have been reported (Depueva and Rotanava 2000; Zakharenkova et al 2007; Zhao et al 2008; Jhuang et al 2010; Devi et al 2010a, 2013; Ryu et al 2014a). Zakharenkova et al (2007) studied the Hokkaido EQ which occurred on September 25, 2003 (M = 8.3) using TEC along with individual satellite passes. These reports suggest that the study of the ionosphere as an EQ precursor has some unforeseen potential for applications as well as for basic research (Devi et al 2010b), it is opined by some that TEC might not be practical for short-term predictions (Astafyeva and Heki 2011)
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