THE MAKRAN EARTHQUAKE OF 1983 APRIL 18 - A POSSIBLE ANALOG TO THE PUGET SOUND EARTHQUAKE OF 1965 Academic Article uri icon

abstract

  • On 1983 April 18, a large earthquake (mb6.5, M0 = 1.2X1019 Nm) occurred in the Makran region near the PakistanIran border. This earthquake is the only event of mb > 6.2 in the entire Makran region since the occurrence of the great Makran earthquake (M= 8.08.3) in 1945. We determined the source parameters of the 1983 event by formally inverting its P and SHwaves recorded by the WorldWide Standard Seismograph Network (WWSSN) and the Canadian Seismograph Network (CSN) at teleseismic distances. The bestfitting centroidal solution shows predominantly normal faulting at a depth of about 65 5 km. These results provide an additional constraint on the configuration of the downgoing slab previously inferred from the occurrence of three small to moderatesized events located 100300 km to the west of the event reported here. We also discuss the possibility of drawing an analogy between the occurrence of the 1983 Makran event and that of the Puget Sound earthquake of 1965 (M01.4X1019Nm, mb 6.5), and between the seismotectonic settings of the two regions. If the very large (M= 8.08.3) earthquake off the Makran coast in 1945 is a lowangle thrust due to slip along the plate interface, its occurrence calls for the possibility of similar seismic risk in the Puget Sound region. However, in contrast to inferences made from geological observations in the field, about a dozen Pwave first motions read from historical seismograms and those reported by the International Seismological Summary suggest that the 1945 Makran earthquake has a large component of normal faulting which can be attributed to the relatively old age of the subducted lithosphere. Copyright 1989, Wiley Blackwell. All rights reserved

published proceedings

  • GEOPHYSICAL JOURNAL INTERNATIONAL

altmetric score

  • 2.5

author list (cited authors)

  • LAANE, J. L., & CHEN, W. P.

citation count

  • 19

complete list of authors

  • LAANE, JL||CHEN, WP

publication date

  • July 1989