NHESSD Natural Hazards and Earth System Sciences Discussions NHESSD Nat. Hazards Earth Syst. Sci. Discuss. 2195-9269 Göttingen, Germany 10.5194/nhessd-1-5643-2013 Study of the 2013 Lushan <i>M</i> = 7.0 earthquake coseismic ionospheric disturbances Chen P. 1 2 Chen J. J. 3 Yao W. Q. 1 Zhang B. 1 College of Geomatics, Xi'an University of Science and Technology, Xi'an 710054, China State Key Laboratory of Geodesy and Earth's Dynamics, Wuhan 430077, China School of Geodesy and Geomatics, Wuhan University, Wuhan 430079, China 16 10 2013 1 5 5643 5662 Copyright: © 2013 P. Chen et al. 2013 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://nhess.copernicus.org/preprints/1/5643/2013/nhessd-1-5643-2013.html The full text article is available as a PDF file from https://nhess.copernicus.org/preprints/1/5643/2013/nhessd-1-5643-2013.pdf

On 20 April 2013, an earthquake of <i>M</i> =7.0 occurred in Lushan, Sichuan province, China. This paper investigates the coseismic ionospheric anomalies using GPS (Global Positioning System) data from 23 reference stations in Sichuan province that are a part of the Crustal Movement Observation Network of China (CMONOC). The recorded results show that a clear ionospheric anomaly occurred within 15 min after the earthquake near the epicenter, and the occurrence time of the anomalies recorded by various stations is related to the distance from the epicenter. The maximum anomaly is 0.25 TECu, with a 2 min duration and the distance of the recording station to the epicenter is 83 km. Acoustic waves generated by the crustal vertical movement during the earthquake propagate up to the height of the ionosphere lead to the ionospheric anomaly, and the propagation speed of the acoustic wave is calculated as 0.72 ± 0.04 km s<sup>-1</sup> based on the propagation time and propagation distance, consistent with the average speed of sound waves within a 0–450 km atmospheric height.

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