Seismic deformations of the land surface during the Spitak earthquake 1988

Abstract

Seismic disjunctive deformations formed during the Spitak earthquake are recorded over large area. Total length of the outlined fault zone (including normal and reverse richt- and left-slip faults) adds up to 35 km. Maximum displacement in reverse faults is up to 2 m, in strike-slips — 1,8 m. The zone consists of three sections of active dislocations, each section having distinct morphological features. While the seismic faults vary widely in near-surface structure, the main fault mostly coincides with older fault-line. The downthrown wall to the latter reveals a sequence of buried soils which suggests repeated movements in the past probably due to earthquakes similar to Spitak one.

Morphology and spatial pattern of seismic dislocations as well as data on the aftershock activity indicate that the Spitak earthquake focus is situated on the intersection of two large fault zones (Sevan - Pambak and Alavar).