March 28, 1787 Tsunami: San Marcos, Mexico

1787, March (mistakenly April) 28 (mistakenly 14 and 18), at 11:30 [local time]. There was a large earthquake with source near San Marcos, affecting the coast of the states of Oaxaca, Guerrero and Michoacan and causing much destruction. The earthquake generated a tsunami that was observed in Acapulco and tore 11 men to pieces and left them to hang between the beams of a rather high bridge 6 km from the sea. The few who were saved were injured and very frightened. A galleon from the Philippine islands was riding in the harbor of Acapulco at a depth of 18 m. During the ebb tide, the water shallowed to 8.5 m. The city was destroyed. The wave was also observed in the region of Pochutla, Tehuantepec and other settlements in the state of Oaxaca. (reference #415)

1787, Mar. 14 (also Mar. 18, Mar. 28). Sea withdrew exposing rocks. Galleon reported 11 m lowering. Other places mentioned by Milne and by Heck are places where the earthquake was felt. Mar. 14 is date given by Belcher. Mallet gives both Mar. 14 and Mar. 18 but points out events on the two dates were probably the same. Mar. 28 is given by Sieberg and by Japan Meteorological Agency (Anon, 1964) and by Milne who also gives Apr. 3 [as end of quake series?]. (reference #79)

1787, Mar. 14 or 18. Mexico, near San Marcos. Felt along coast of Oaxaca, Michoacan, and south of Tehuantepec. Sea retired, leaving rocks of Punta Manzanilla dry, and returned very high, estimated at 36 feet by vessel at anchor." References Mallet (reference #497) and Becher (reference #1913). (reference #132)

1787 March 14. A violent earthquake in Acapulco. The sea retired as far as some rocks lying in the middle of the bay. The galleon of the Philippine Isles, which was mooored in 10 fathom water, found but 4 fathoms when the sea had retreated. The city was ruined. (reference #497)

1787, March 18, in the morning. Earthquake in Mexico extending from San Luigi de Potosi to Oaxaca, and from Vera-Cruz to Acapulco and Valladolid. Earthquake shocks from the S.E. At the city of Mexico the earth was in almost continual agitation for 24 hours. At Acapulco the sea retreated far from the shore, and returned high above its former level. From this circumstance it seems probable that the event of the 14th March has either been confounded with, or was the same at this. The city of Oaxaca was most injured. (reference #497)

The 1787 tsunami is not reported in the Japanese catalogs. As Hatori (1995) points out, the coast of Mexico faces the southwest Pacific and a tsunami generated on the Middle American Trench would not radiate energy towards Japan. If the tsunami propagated away from the coast of Mexico, it would have been observed on Easter Island and the Tuamotus; unfortunately, no written records existed on these islands at that time. (reference #14084)