Ionospheric precursors for crustal earthquakes in Italy

Abstract

Abstract.Crustal earthquakes with magnitude 6.0>M≥5.5 observed in Italy for the period 1979-2009 including the last one at L'Aquila on 6 April 2009 were considered to check if the earlier obtained relationships for ionospheric precursors for strong Japanese earthquakes are valid for the Italian moderate earthquakes. The ionospheric precursors are based on the observed variations of the sporadic E-layer parameters (h Es, fbEs) and foF2 at the ionospheric station Rome. Empirical dependencies for the seismo-ionospheric disturbances relating the earthquake magnitude and the epicenter distance are obtained and they have been shown to be similar to those obtained earlier for Japanese earthquakes. The dependences indicate the process of spreading the disturbance from the epicenter towards periphery during the earthquake preparation process. Large lead times for the precursor occurrence (up to 34 days for M=5.8-5.9) tells about a prolong preparation period. A possibility of using the obtained relationships for the earthquakes prediction is discussed.

Ionospheric anomalies detected by ionosonde and possibly related to crustal earthquakes in Greece

“…The approach proposed by Khegai (2006, 2008) and successively developed by Perrone et al (2010) may be considered an improved attempt to obtain a quantitative relationship for seismo-ionospheric anomalies. The main idea is based on the results of a theoretical analysis by Kim et al (1993Kim et al ( , 1994, who showed that the electric field above the preparation zone of future earthquakes can penetrate into the ionosphere to form a dense sporadic layer Es at 120-140 km height above the earthquake preparation zone.…”

“…A distinguishing feature of our analysis is the multiparameter approach, which takes into account the variations of three parameters simultaneously in Es and regular F2 layers (Korsunova and Khegay, 2008;Perrone et al, 2010;Villalobos et al, 2016). Perrone et al (2010) have considered all crustal M > 5.0 earthquakes and a hypocentral depth < 50 km, and with the ionospheric observatory inside the preparation zone.…”

“…Perrone et al (2010) have considered all crustal M > 5.0 earthquakes and a hypocentral depth < 50 km, and with the ionospheric observatory inside the preparation zone. The long-living ( t ∼ 2-3 h) sporadic Es layers revealed and used in the analysis occurred at heights of ≥ 10 km higher than normal Es for corresponding geophysical conditions.…”

Is there any difference in local time variation in ionospheric F2-layer disturbances between earthquake-induced and Q-disturbance events?

“…A total of 736 M>6.0 earthquakes worldwide during 2002-2010 were statically studied using TEC data, and the feature of LT variation in ionospheric anomalies was confirmed . Moreover, empirical dependencies of the seismo-ionospheric disturbances relating the earthquake magnitude and the epicenter distance were discussed by means of statistical analysis (Perrone et al, 2010;Saradjian and Akhoondzadeh, 2011). However, the existence of the seismo-ionospheric precursors is still an open issue because of high ionospheric variability and the influence of solar activity.…”

Nonlinear dynamics, seismic activity and aerospace sounding systems

“…В этом контексте рядом исследователей выска-зывается мнение, что предвестники в ионосфе-ре можно идентифицировать лишь с некото-рой вероятностью из-за большой изменчиво-сти этой области околоземного пространства, так как имеется часть ионосферных аномалий, которые не сопровождаются сейсмическими событиями даже в спокойных геомагнитных условиях [Perrone et al, 2010].…”