Deformation pattern of the 6 and 7 April 2009, MW=6.3 and MW=5.6 earthquakes in L'Aquila (Central Italy) revealed by ground and space based observations
- 1Laboratory of Mineralogy & Geology, Department of Geological Sciences and Atmospheric Environment, Agricultural University of Athens, 75 Iera Odos Str., 118 55, Athens, Greece
- 2AON Benfield Hazard Research Centre, Department of Earth Sciences, Birkbeck College and University College London, WC1E 6BT, London UK
- 3Department of Geophysics – Geothermics, National and Kapodistrian University of Athens, Panepistimioupolis, Ilissia, 157 84, Athens, Greece
- 4Department of Geography, Harokopio University of Athens, El. Venizelou 70, Kallithea, 176 71, Athens, Greece
- 5Department of Dynamic, Tectonic and Applied Geology, National and Kapodistrian University of Athens, Panepistimioupolis, Ilissia, 157 84, Athens, Greece
Abstract. The deformation pattern of the 6 and 7 April 2009 MW=6.3 and MW=5.6 earthquakes in L'Aquila is revealed by DInSAR analysis and compared with earthquake environmental effects. The DInSAR predicted fault surface ruptures coincide with localities where surface ruptures have been observed in the field, confirming that the ruptures observed near Paganica village are indeed primary. These ruptures are almost one order of magnitude lower than the ruptures that have been produced by other major surrounding faults in the past. These faults have not been activated during the 2009 event, but have the capacity to generate significantly stronger events. DInSAR analysis shows that 66% (or 305 km2) of the area deformed has been subsided whereas the remaining 34% (or 155 km2) has been uplifted. A footwall uplift versus hangingwall subsidence ratio of about 1/3 is extracted from the mainshock. The maximum subsidence (25 cm) was recorded about 4.5 km away from the primary surface ruptures and about 9 km away from the epicentre. In the immediate hangingwall, subsidence did not exceeded 15 cm, showing that the maximum subsidence is not recorded near the ruptured fault trace, but closer to the hangingwall centre. The deformation pattern is asymmetrical expanding significantly towards the southeast. A part of this asymmetry can be attributed to the contribution of the 7 April event in the deformation field.