Indian explosions of 11 May 1998: analysis of regional Lg and Rayleigh waves

Abstract

This paper presents the analysis of regional Lg and Rayleigh wave data pertaining to the Indian explosions of 11 May 1998 (POK2). Strong Lg and Rayleigh waves have been recorded at several in-country stations. A comparison of Lg waves at Gauribidanur array (GBA), India corresponding to POK2 and that of the Indian explosion of May 1974 (POK1) shows an amplitude ratio of 3.7 between these events. This leads to a yield ratio of 4.83 between the two events. Analysis of Rayleigh waves revealed that Nuttli’s relation for estimation of surface wave magnitude (M_s) in the period range 3.0–12.0 s based on eastern North American data is also applicable for the Indian region. The average M_s value of POK2 from regional data is obtained as 3.56. The yield estimate of POK2 as obtained from the regional data analysis is found consistent with our earlier findings and the post shot radiochemical measurements.