Articles | Volume 16, issue 8
Research article
12 Aug 2016
Research article |  | 12 Aug 2016

Geosphere coupling and hydrothermal anomalies before the 2009 Mw 6.3 L'Aquila earthquake in Italy

Lixin Wu, Shuo Zheng, Angelo De Santis, Kai Qin, Rosa Di Mauro, Shanjun Liu, and Mario Luigi Rainone

Abstract. The earthquake anomalies associated with the 6 April 2009 Mw 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 CO2-rich fluids in deep crust might have played a significant role in the local LCAC process.

Short summary
Many anomalies before the 2009 L'Aquila earthquake were reported but not synergically analyzed referring to geosystem coupling. We investigated changes of multiple hydrothermal parameters in coversphere and atmosphere and studied 3-D evolution of b value in lithosphere. Quasi-synchronism of pre-earthquake anomalies georelating to particular thrusts and local topography are revealed. A geosphere coupling mode is proposed interpreting the function of CO2-rich crust fluids on local LCA coupling.
Final-revised paper