A revised earthquake catalogue for the Eastern Caribbean Region : 1513-1992

ABSTRACT

We presente a revised earthquake catalogue for the eastern Caribbean region 8 N to 22.5 N, 58 W to 70 W covering the period 1530 to 1993. Sizes of all events for which sufficient information exists have been expressed in terms of seismic moment either measured directly or derived from earthquake magnitude by theoretical and empirical formulae. From 1530 to 1900 the sources of information consist entirely of written accounts of felt earthquakes. The completeness of this part of the catalogue varies throughout the region but it is probably complete down tro magnitude (M06.5 to 7 since 1800 and perhaps as far back as 1600 for some parts of the region. From 1900 onwards an increasing number of instrumentally-determined epicentres and magnitudes are available but reports of felt earthquakes continued to exceed instrumental observations at least until 1950. During this period the lower magnitude for completeness is in the range of 5.5 to 6. After 1950 the establishment of more modern seismograph stations within the region gradually improved the location threshold but the major improvement did not occur until 1964 when the almost simultaneous completion of the WWSSN and the establishment of the ISC further reduced the threshold to about 4.0. Within limited regions such as the central Lesser Antilles and the Trinidad-Tobago region where local seismograph systems are particualrly efficient the location threshold is now down to the microearthquake level.(AU)