Backprojection analyses from four regional arrays for rupture over a curved dipping fault: The M(w)7.7 24 September 2013 Pakistan earthquake

摘要

We analyzed the 24 September 2013 Pakistan earthquake (M(w)7.7) with backprojection analyses using data recorded on four different regional arrays in Europe, China, and Japan (Hi-net and F-net). The results from all the arrays show propagation of the rupture toward the southwest for duration of about 40-50s. Among them, results for Hi-net and a subset of China array show a clear segment of fast rupture propagation, with a rupture speed probably faster than the local shear wave velocity. Resolutions of the results from the various arrays are investigated using bootstrap tests, backprojection of aftershocks, and numerical tests with synthetic source models. The results of those tests show differences in the quality of the results from the four arrays. The China array and the Hi-net in Japan show the best results for this case. F-net in Japan shows the poorest results because of the few number of stations. The locations of large amplitudes (equivalent to a M6.8 event) have absolute uncertainties of about 20 to 30km (ignoring the source dimension).