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Ionospheric anomalies immediately before M(w)7.0-8.0 earthquakes

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Please use this identifier to cite or link to this item:http://hdl.handle.net/2115/68270

Title: Ionospheric anomalies immediately before M(w)7.0-8.0 earthquakes
Authors: He, Liming Browse this author
Heki, Kosuke Browse this author →KAKEN DB
Keywords: ionospheric anomalies
earthquake
GNSS
total electron content
Issue Date: Aug-2017
Publisher: American Geophysical Union
Journal Title: Journal of geophysical research. Space physics
Volume: 122
Issue: 8
Start Page: 8659
End Page: 8678
Publisher DOI: 10.1002/2017JA024012
Abstract: Recent observations suggested that ionospheric anomalies appear immediately before large earthquakes with moment magnitudes (M-w) of 8.2 or more. Do similar phenomena precede smaller earthquakes? Here we answer this question by analyzing vertical total electron contents (VTEC) observed near the epicenters before and after 32 earthquakes with M(w)7.0-8.0 using data from nearby Global Navigation Satellite Systems stations. To detect anomalies, we defined the reference curves to fit the observed VTEC and considered the departure from the curves as anomalies. In estimating the reference curves, we excluded time windows, prescribed for individual earthquakes considering M-w, possibly affected by earthquakes. We validated the method using synthetic VTEC data assuming both preseismic, coseismic, and postseismic anomalies. Out of the 32 M(w)7.0-8.0 earthquakes, eight earthquakes showed possible preseismic anomalies starting 10-20min before earthquakes. For earthquakes of this M-w range, we can observe preseismic ionospheric changes probably when the background VTEC is large, say 50TECU (total electron content unit, 1TECU=10(16) el m(-2)) or more.
Rights: Copyright 2017 American Geophysical Union.
Type: article
URI: http://hdl.handle.net/2115/68270
Appears in Collections:理学院・理学研究院 (Graduate School of Science / Faculty of Science) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 日置 幸介

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