Analysis of ionospheric anomaly preceding the Mw7. 3 Yutian earthquake

Abstract

On February 12, 2014, a large Mw7. 3 earthquake occurred in Yutian of Xijiang Province, China.We processed the global ionosphere maps provided by CODE (the Center for Orbit Determination in Europe ) and the foF2 (the critical frequency of F2-layer) data of Chongqing ionosonde station to analyze the preearthquake ionospheric anomalies. Solar activities and magnetic storm were checked by the sliding inter quartile range method to remove their effects on the ionosphere. A positive ionospheric anomaly with the large amplitude of 20 TECU was observed near the epicenter on February 3 ( lOth day before the earthquake). In addition, the foF2 at Chongqing station had an unusual increase of more than 40% on the day, which was consistent with the TEC (Total Electron Content) anomaly. The global disturbance represents that the peak of TEC anomaly didn't coincide with the vertical projection of epicenter. The TEC anomalous area was closer to the equator, and it mainly occurred from local time 16 : 00 to 20 : 00. An enhancement of TEC with the small amplitude also appeared in the magnetically conjugated region.

Pacific subduction control on Asian continental deformation including Tibetan extension and eastward extrusion tectonics

“…The infinitesimal displacement fields for the last stage of the experiments (Fig. 5a–c), which represent the present-day displacement field, are generally consistent with and comparable to the Global Positioning System (GPS) velocity field observed in Central and East Asia 27 . Indeed, both experimental and observational fields show approximately radially divergent vectors north of the Indian indenter that decrease in length with increasing distance from the indenter, east-directed vectors in central and northern East Asia and a clockwise rotating vector pattern near the northeast corner of the indenter and in Southeast Asia.…”

Thermal Infrared and Ionospheric Anomalies of the 2017 Mw6.5 Jiuzhaigou Earthquake

“…When earthquake electromagnetic signals propagate into the ionosphere, they can cause a disturbance of related ionospheric parameters [15][16][17][18][19][20][21][22], and satellite can observe those seismic electromagnetic effects. Since the ionospheric disturbance phenomenon was first observed over the epicenter of the 1960 M9.2 Alaska earthquake, a large number of statistical analyses have shown corresponding disturbance phenomena in the atmosphere and ionosphere above epicentral zones in the days to hours before earthquakes [23][24][25][26][27][28][29][30][31]. When describing ionospheric disturbances, the total electron content (TEC) is an important parameter.…”

Ionospheric anomalies preceding the low-latitude earthquake that occurred on April 16, 2016 in Ecuador

“…The search for earthquake precursors in the ionosphere is a very active field of research (e.g. Liu et al, 2004;Zakharenkova et al, 2006Zakharenkova et al, , 2008Zhao et al, 2008;Mubarak et al, 2009;Zhu et al, 2010;Zou and Zhao, 2010;Yao et al, 2012;Zhu et al, 2013;Wang et al, 2014;Xinzhi et al, 2014;Li et al, 2015;Guo et al, 2015;Pundhir et al, 2015;Alcay, 2016). There are studies that for example concentrate on a particular earthquake and through the employment of different techniques, they are able to identify ionospheric anomalies that appear a few days before and which are associated to an earthquake.…”