On the geodetic observations during 1965 to 1969 in the Koyna region, India

Limited reports of repeat triangulation and levelling surveys carried out i n the Koyna region by Survey of India, before and after the 1967 Koyna eart hquake, are available. We analyse these observations of horizontal and vert ical displacements to investigate whether analysis of these observations ca n provide additional constraints on the source parameters of the 1967 Koyna earthquake. We calculate surface displacements due to coseismic slip on th e subsurface rupture of the 1967 Koyna earthquake and also due to the Koyna reservoir water load. We find that the reported displacements are too larg e to be attributed to the coseismic displacements and/or to the displacemen ts induced by the reservoir water load. We conclude that these observations contain large random and systematic errors. (C) 2001 Elsevier Science Ltd. All rights reserved.