GNGTS 2015 - Atti del 34° Convegno Nazionale

GNGTS 2015 S essione 1.1 53 A different interpretation was proposed by Bilham and England (2001). They interpret the Shillong Plateau as a pop-up structure; for them, the causative fault is a SSW-dipping plane close to the auxiliary one in the beach ball in Fig. 2B (drawn in white to emphasize the limitation of the KF standard procedure). Source inversion of the M S 8.2 Bihar-Nepal, 1934 earthquake. Fig. 2C shows the MSK intensities of the M S 8.2 Bihar-Nepal, 1934 earthquake reported by Ambraseys and Douglas (2004) in 65 towns and villages (dots) within 120 km epicentral distance. Fig. 2D shows the synthetic intensities and the beach ball diagram that was produced by the minimum variance model of column 3 of Tab. 1 (interpolation as in Fig. 2C). The match of Fig. 2D is good. In this case we can compare our results with two instrumental epicenters (we refer to those by Chen and Molnar (1977) and by Singh and Gupta (1980)) and with one fault-plane solution (Singh and Gupta, 1980). Then, there is a precious amount of palaeo-seismic data by Sapkota et al. (2013) who found the 1934 co-seismic rupture of a segment of MFT (refer to the wavy path of the southern side of polygon (A) in Fig. 1). By the way, the findings by Sapkota et al. (2013) definitely contradict the results offered by Singh and Gupta (1980). The projection of our source Fig. 2 – A) Field intensities (MSK scale, 31 data) of the M S 8.1, 1897 Shillong earthquake; the isoseismals were traced with the n-n bivariate interpolation scheme (Sirovich et al. , 2002). B) Synthetic intensities and the beach ball diagram that was produced by the minimum variance model of column 3 of Tab. 1; interpolated as in (A). C) Same as in Fig. 2A, 65 data, MS 8.2, 1934 Bihar-Nepal earthquake (star and cross as in Fig. 1). D) Synthetic intensities and the beach ball diagram as in Fig. 2B for the MS 8.2, 1934 Bihar-Nepal earthquake (see Tab. 2, column 3) (polygon and rectangle as in Fig. 1).