Robust satellite techniques (RST) for the thermal monitoring of earthquake prone areas: the case of Umbria-Marche October, 1997 seismic events

V Tramutoli V Tramutoli,C Aliano C Aliano,R Corrado R Corrado,C Filizzola C Filizzola,N Pergola N Pergola

doi:10.4401/ag-3025

Abstract

Several authors claim a space-time correlation between increases in Earths emitted Thermal Infra-Red (TIR) radiation and earthquake occurrence. The main problems of such studies regard data analysis and interpretation, which are often done without a validation/confutation control. In this context, a robust data analysis technique (RST, i.e. Robust Satellite Techniques) is proposed which permits a statistically based definition of TIR «anomaly » and uses a validation/confutation approach. This technique was already applied to satellite TIR surveys in seismic regions for about twenty earthquakes that occurred in the world. In this work RST is applied for the first time to a time sequence of seismic events. Nine years of Meteosat TIR observations have been analyzed to characterize the unperturbed TIR signal behaviour at specific observation times and locations. The main seismic events of the October 1997 Umbria-Marche sequence have been considered for validation, and relatively unperturbed periods (no earthquakes with Mb ? 4) were taken for confutation purposes. Positive time-space persistent TIR anomalies were observed during seismic periods, generally overlapping the principal tectonic lineaments of the region and sometimes focusing on the vicinity of the epicentre. No similar (in terms of relative intensity and space-time persistence) TIR anomalies were detected during seismically unperturbed periods.

Highlights

The main problems in the above-mentioned studies were the lack of a rigorous definition of anomalous Thermal Infrared (TIR) signal fluctuations, the absence of a convincing testing step based on a validation/confutation approach and the scarce attention paid to the possibility that causes other than seismic activity could be responsible for the observed TIR variations (Tramutoli et al, 2005)
On the investigated area are shown where space-time TIR signal transients, both in the presence and absence of seismic events, will be analysed looking for possible space-time relationships with earthquake occurrence
The relation between TIR anomalies appearance and earthquake magnitude does not seem in contrast with the indications from the study performed by Corrado et al (2005) on low-medium earthquakes (4

Summary

Introduction

A growing number of studies (Gorny et al, 1988; Ouzounov et al, 2006; Ouzounov et al, 2007; Pulinets et al, 2006a; Qiang et al, 1991, Qiang et al, 1992, Qiang et al, 1997; Saraf and Choudhury, 2005a, Saraf and Choudhury, 2005b; Tronin, 1996; Tronin, 2000; Tronin et al, 2002) based on Thermal Infrared (TIR)(1) meteorological satellite data have reported large scale (up to hundreds km) positive variations (from 3 to 6 K) of Earth’s TIR emission during a time (from weeks to days) before earthquake occurrence, suggesting a possible relation between «anomalous» space-time fluctuations of such TIR signal and earthquake occurrence. The main problems in the above-mentioned studies were the lack of a rigorous definition of anomalous TIR signal fluctuations, the absence of a convincing testing step based on a validation/confutation approach and the scarce attention paid to the possibility that causes (e.g. meteorological) other than seismic activity could be responsible for the observed TIR variations (Tramutoli et al, 2005) Several authors interpreted such thermal signals as pre-seismic, invoking different natural processes to explain the origin of enhanced TIR emission, among them: (a) rising fluids that would lead to the emanation of warm gases (Salman et al, 1992; Gorny et al, 1988); (b) rising well water levels and CO2 spreading laterally causing a «local greenhouse» effect (Qiang et al.,1991; Tronin et al, 2002; Tramutoli et al, 2005); (c) activating positive-hole pairs during rock deformation (Freund, 2002); (d) Air ionization by radon and latent heat change due to change of air humidity (Pulinets et al, 2006b). (2) Advanced Very High Resolution Radiometer onboard NOAA (National Oceanographic and Atmospheric Administration) platforms. (3) Geostationary Operational Environment Satellites operated by NOAA

The case of October 1997 Umbria-Marche earthquakes

Validation

Confutation

Conclusions