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IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy
(S) - IASPEI - International Association of Seismology and Physics of the Earth's
Interior
JSS010 Oral Presentation 2076
Robust Satellite Techniques (RST) for seismically active areas monitoring:
Dr. Carolina Aliano
DIFA UNIBAS
Rosita Corrado, Carolina Filizzola, Pergola Nicola, Valerio Tramutoli
In the last 20 years an increasing number of studies based on TIR satellite data have reported spacetime
fluctuations of earths emitted TIR radiation during a time (from weeks to days) before earthquake
occurrence. Several authors interpreted such thermal signals as seismic precursors, suggesting different
explanatory models. More recently, a Robust Satellite data analysis Technique (RST) was
proposedwhich has turned out as a suitable tool for satellite TIR surveys in seismically active regions.
Compared with other methods, RST offers an unambiguous (statistically founded) definition of TIR
anomaly and improved capability to identify anomalous space-time TIR signal variations even in very
variable observational (satellite view angle, land topography and coverage, etc.) and natural (e.g.
meteorological) conditions. In this work RST is applied for the first time to a seismic sequence for better
understanding the relationship between TIR anomaly intensity and earthquake magnitude and/or depth,
being the same the geologic conditions. The 1997-1998 Umbria-Marche seismic sequence was
considered because the region of Central Appennines is one of the more degassing area in . The
enhanced green-house gas emission is in fact one of the proposed cause for the appearance of TIR
anomalies in relation with seismic activity. Nine years of Meteosat TIR observations have been analyzed
in order to characterize the TIR signal behaviour in absence of significant seismic activity at each
specific observation time and location. Space-time TIR signal transients have been then analyzed, both
in presence (validation) and in absence of (confutation) seismic events, looking for possible space-time
relationships. The main (Mb >4) seismic events of the sequence have been considered as test cases for
validation, and relatively unperturbed periods (no earthquakes with Mb >4) were taken for confutation
purposes. The observations show that the area of interest is affected by positive time-space persistent
TIR anomalies during periods of seismic activity. Such anomalies generally overlap the principal tectonic
lineaments of the region, sometimes focusing in the vicinity of the earthquake epicentre. As far as the
confutation analysis is concerned, the results well highlight that no similar (in terms of relative intensity
and space-time persistence) TIR anomalies were detected during seismically unperturbed periods.
Keywords: earthquake, satellite therma linfrared, umbria marche