Seismically active area monitoring by robust TIR satellite techniques: a sensitivity analysis on low magnitude earthquakes in Greece and Turkey

Abstract

Part of Special Issue "Precursory phenomena, seismic hazard evaluation and seismo-tectonic electromagnetic effects" Abstract. Space-time TIR anomalies, observed from months to weeks before earthquake occurrence, have been suggested by several authors as pre-seismic signals. Up to now, such a claimed connection of TIR emission with seismic activity has been considered with some caution by scientific community mainly for the insufficiency of the validation data-sets and the scarce importance attached by those authors to other causes (e.g. meteorological) that, rather than seismic activity, could be responsible for the observed TIR signal fluctuations. A robust satellite data analysis technique (RAT) has been recently proposed which, thanks to a well-founded definition of TIR anomaly, seems to be able to identify anomalous spacetime TIR signal transients even in very variable observational (satellite view angle, land topography and coverage, etc.) and natural (e.g. meteorological) conditions.Its possible application to satellite TIR surveys in seismically active regions has been already tested in the case of several earthquakes (Irpinia: 23 November 1980, Athens: 7 September 1999, Izmit: 17 August 1999) of magnitude higher than 5.5 by using a validation/confutation approach, devoted to verify the presence/absence of anomalous spacetime TIR transients in the presence/absence of seismic activity. In these cases, a magnitude threshold (generally M<5) was arbitrarily chosen in order to identify seismically unperturbed periods for confutation purposes.In this work, 9 medium-low magnitude (4<M b <5.5) earthquakes which occurred in Greece and Turkey have been analyzed in order to verify if, even in these cases, anomalous TIR transients can be observed.The analysis, which was performed using 8 years of Meteosat TIR observations, demonstrated that anomalous TIR transients can be observed even in the presence of mediumlow magnitude earthquakes (4<M b <5.5). As far as the Correspondence to: C. Filizzola (filizzola@imaa.cnr.it) research (just started) of possible correlation among TIR anomalies and earthquake occurrence is concerned, such a result suggests that: a) in order to identify seismically unperturbed periods for confutation purposes, a magnitude threshold (at least) lower than 4 should be used; b) the proposed validation/confutation approach should be applied in lowseismicity areas in order to find suitably long seismically quiescent periods.

RST analysis of MSG-SEVIRI TIR radiances at the time of the Abruzzo 6 April 2009 earthquake

“…Corrado et al, 2005) is confirmed, in fact TIR anomalies persistent in the space-time domain have been observed in Italy from few days to few weeks before seismic events of medium-low magnitude (Calabria,8 An original approach to identify and exclude TIR anomalies purely due to the effect (already described in Aliano et al, 2008a) of cloud cover and spatial distribution was proposed. Nevertheless the presence of clouds continue to limit the possibility to well investigate space-time persistence of TIR anomalies.…”

“…RST was applied for the first time to seismically active areas monitoring, in the case of the disastrous 1980 Irpinia-Basilicata earthquake (Di Bello et al, 2004;Tramutoli et al, 2001b), then it was successfully tested in several cases: Athens, 7 September 1999 ; Izmit, 17 August 1999 ; Gujarat, 26 January 2001 (Genzano et al, 2007), Boumerdes/Thenia, 21 May 2003(Aliano et al, 2007; Hector Mine, 16 October 1999(Aliano et al, 2008a, Umbria-Marche, October 1997 (Aliano et al, 2008b), Mestia Tianeti (Georgia), 23 October 1992 , and various low magnitude events occurred in Greece and Turkey, May and June 1995-1996(Corrado et al, 2005.…”

“…The RST approach was already tested in the case of tens of earthquakes (Tramutoli et al, 2001bDi Bello et al, 2004;Corrado et al, 2005;Genzano et al, 2007Genzano et al, , 2009Aliano et al, 2007Aliano et al, , 2008a occurred in different continents (Europe, Asia, America and Africa), in various geo-tectonic settings (compressive, extensional and transcurrent) and with a wide range of magnitudes (from 4.0 to 7.9).…”

A study on the Abruzzo 6 April 2009 earthquake by applying the RST approach to 15 years of AVHRR TIR observations

“…Tramutoli et al, 2001bTramutoli et al, , 2005Tramutoli et al, , 2009Di Bello et al, 2004;Corrado et al, 2005;Genzano et al, 2007Aliano et al, 2007Aliano et al, , 2008a.…”

“…After its first application to the 1980 Irpinia-Basilicata's earthquake (Di Bello et al, 2004;Tramutoli et al, 2001b) RST has been applied to seismically active area monitoring for several other earthquake events: Athens, 7 September 1999 ; Izmit, 17 August 1999 (Tramutoli et al, 2005); Gujarat, 26 January 2001 (Genzano et al, 2007), Boumerdes/Thenia, 21 May 2003(Aliano et al, 2007; Hector Mine, 16 October 1999 (Aliano et al, 2008a), UmbriaMarche, October 1997 (Aliano et al, 2008b), Mestia Tianeti (Georgia) 23 October 1992 ) and various seismic events occurred in Greece and Turkey, in May and June 1995-1996(Corrado et al, 2005.…”