Source Parameters of the September 10, 2008 Qeshm Earthquake in Iran Inferred from the Bayesian Inversion of Envisat and ALOS InSAR Observations

This paper presents InSAR observations and source parameter results for September 10, 2008 Qeshm Island (Mw 6.1) earthquake in Iran. An ascending ALOS interferogram and two Envisat interferograms from ascending and descending orbits are used to derive coseismic displacement field of the earthquake. Interferometric observations show coseismic displacement of more than 10cm in the northern part of the island. To obtain source parameters of the earthquake and their associated posteriori probability distribution we use the Bayesian approach. The inversion is done in a two-step process. First we derive, using the Simulated Annealing (SA) method, the posterior marginal distribution of parameters to determine their sensitivity to the observations. This step is important as it determines which parameters can be resolved reliably by the inversion of geodetic data and which ones need to be constrained by other sources. Following the above procedure, we use a Genetic Algorithm (GA) to find the maximum Bayesian probability for each parameter. We find that InSAR observations of 2008 Qeshm earthquake are consistent with an average thrust motion of 75cm that occurred on an∼13 ×3km fault plane with a centroid depth of∼5km, striking 218∘ and dipping north at 33∘.