On October 11, 1918, an earthquake occurred, with an approximate magnitude of 7.3 on the Richter scale, accompanied by a tsunami reaching 6.1 metres (20 ft) in height. The epicenter was located northwest of Aguadilla in the Mona Passage (between Puerto Rico and the Dominican Republic). This earthquake caused great damage and loss of life at Mayagüez, and lesser damage along the west coast. Tremors continued for several weeks. Approximately 116 casualties were reported resulting from the earthquake and 40 from the tsunami.