A major earthquake (mb = 6.6; Ms = 7.5, U.S. Geological Survey) occurred in the northern Lesser Antilles on October 8, 1974, causing damage of Modified Mercalli intensity VIII on the island of Antigua and lower intensities on the more distant islands.
The damage was confined mainly to larger and older buildings, to a petroleum refinery, and to a deep-water harbor. No earthquake-resistant building code exists in most of the Lesser Antilles, and in the majority of cases examined it was clear that structural damage had occurred because the building concerned could not have met the elementary requirements of a typical code.
A few people received minor injuries, but no fatality was reported.
The hypocenter of the main shock and many of the aftershocks lay about 30 km above the westward-dipping zone defined by activity over the last decade. The earthquake was tectonic in origin since the epicenter was 50 km from the nearest recent volcano.