Crustal structure beneath the Maltese Islands from receiver functions at WDD seismic station

Abstract

The primary objective of this study was to shed light on the crustal structure underlying the Maltese Islands using the receiver function analysis technique. The data analysed in this work consisted of teleseismic events recorded by the MEDNET station WDD. Events with an epicentral distance ranging between 25° and 90° and a magnitude higher or equal to 6.0 were considered. Signals with a high signal-to-noise ratio were kept whilst the rest were discarded. A stacked receiver function was obtained after Langston 's deconvolution technique was applied to each of the 20 three-component data sets. The forward modelling procedure was then carried out on the stack and the best-fitting velocity model for the region was selected. The major discontinuities were predicted to be at 10 km, 22 km and 35 km. The intermediate layer between the 22- and the 35-km boundaries conformed to existing velocity models. Such a feature is particularly associated with continental rift systems. The inversion technique was carried out on the stack of the receiver functions and three distinct velocity models were attained. Even though the two methods did not give drastically different results, the model obtained by forward modelling appeared to be more consistent with known geological data than those obtained from inverse modelling.