Geosphere coupling and hydrothermal anomalies before the 2009 <i>M</i><sub>w</sub> 6.3 L'Aquila earthquake in Italy

Abstract

Abstract. The earthquake anomalies associated with the 6 April 2009 M w 6.3 L'Aquila earthquake have been widely reported. Nevertheless, the reported anomalies have not been so far synergically analyzed to interpret or prove the potential lithosphere-coversphere-atmosphere coupling (LCAC) process. Previous studies on b value (a seismicity parameter from Gutenberg-Richter law) are also insufficient. In this work, the spatiotemporal evolution of several hydrothermal parameters related to the coversphere and atmosphere, including soil moisture, soil temperature, near-surface air temperature, and precipitable water, was comprehensively investigated. Air temperature and atmospheric aerosol were also statistically analyzed in time series with ground observations. An abnormal enhancement of aerosol occurred on 30 March 2009 and thus proved quasi-synchronous anomalies among the hydrothermal parameters from 29 to 31 March in particular places geo-related to tectonic thrusts and local topography. The three-dimensional (3-D) visualization analysis of b value revealed that regional stress accumulated to a high level, particularly in the L'Aquila basin and around regional large thrusts. Finally, the coupling effects of geospheres were discussed, and a conceptual LCAC mode was proposed to interpret the possible mechanisms of the multiple quasi-synchronous anomalies preceding the L'Aquila earthquake. Results indicate that CO 2 -rich fluids in deep crust might have played a significant role in the local LCAC process.

Land – Atmosphere – Meteorological coupling associated with the 2015 Gorkha (M 7.8) and Dolakha (M 7.3) Nepal earthquakes

“…Few days prior to the impending earthquake, thermal anomalies observed associated with the enhanced tectonic activities. The upwelling of underground fluids increases the soil moisture (Wu et al, 2016), which can promote hydrothermal exchange as the temperature increases that may enhance latent heat flux. Meanwhile, the lower atmospheric disturbance over the seismogenic zone will propagate upward into the ionosphere through different ways (chemical, acoustic or electromagnetic) causing ionospheric disturbances (Hayakawa and Molchanov, 2004).…”

“…In recent years, efforts have been made to understand the precursory mechanism through the analysis of multi-parameters of the lithosphere, atmosphere and ionosphere of earthquake events. Synchronous or near-synchronous variations were observed associated with different parameters of lithosphere and atmosphere of 2003 Colima (M = 7.8) (Pulinets et al, 2006), 2004 Sumatra (M = 9.1) (Singh et al, 2007(Singh et al, ), 2008 Wenchuan (M = 7.8) (Singh et al, 2010b;Jing et al, 2013), 2009 L'Aquila (M = 6.3) (Wu et al, 2016), 2010 Haiti (M = 7.0) (Singh et al, 2010c), 2016 Ecuador (M = 7.8) (Akhoondzadeh et al, 2018) and several other earthquakes. These results have clearly demonstrated existence of coupling between lithosphere-atmosphere-ionosphere associated with the earthquake activities.…”

Pre-seismic anomalies from optical satellite observations: a review

“…The general anomaly method is to find the difference between current data during an earthquake and the long-term average value (also called a reference value) in order to improve result robustness and eliminate potential bias (Mahmood et al, 2017;Qin et al, 2014a;Wu et al, 2016). This method can be expressed as…”

“…The purpose of SSTAs is similar to that of a deviationtime-space-thermal (DTS-T) anomaly recognition method proposed by Wu et al (2012), which is applied to analyses of several large earthquakes. The DTS-T method defines a normalized quantitative index to express the stability of thermal anomalies considering the significance of numerical differences, synchronization of time, and adjacency of geographical location.…”

“…5 using three anomaly detection methods in order to reduce uncertainty of detecting anomaly date (Akhoondzadeh, 2015). An anomalous increase of ground-measured AOD is quasisynchronous with several abnormal hydrothermal parameters (Wu et al, 2016). Over the sea surface, significant changes in aerosol parameters are considered to be related to the 2001 Gujarat earthquake (Okada et al, 2004).…”