April 7, 1845 Tsunami: S. Mexico

April 7, 1845, 15:30 [local time], 17.5 N, 101.5 W, magnitude 8.5. At Acapulco, there was an earthquake and then a tsunami. The earthquake began with oscillations, whose intensity gradually increased until they became very strong. In half an hour, an enormous wave appeared at sea. It penetrated approximately 40 m (50 vara) inland; then the water rapidly retreated, exposing the bottom for 35 m (42 vara), after which the oscillations in sea level abated little by little. This earthquake was observed at many places in the states of Guerrero, Michoacan, Puebla, Hidalgo, Guanajuato, Colima, VeraCruz, San Luis Potosi, Queretaro, Jalisco and Oaxaca, and also in Mexico City, where homes and arcades of the water main were damaged. The cupola of Saint Theresa Cathedral collapsed. (reference #415)

April 7, 1845. The earthquake with a magnitude Ms=7.9 occurred in front of the Acapulco coast (16 N,99.2 W). It started with a slight oscillation, which gradually increased in intensity. It was felt in the States of Guerrero, Michoacan, Puebla, Hidalgo, Guanajuato, Colima, Veracruz, San Luis Potosi, Queretaro, Jalisco, Oaxaca and Mexico City, where the dome of the Santa Teresa cathedral collapsed. In Acapulco, a huge wave flooded a horizontal extension of approximately 40 m; then, the wafer returned uncovering an extension of 35 m of sea bed. (reference #369)

[…] a tsunami was reported in Acapulco. The local governor of Autlan, Jalisco (AGN, 1845), reported that the earthquake “was felt at the coast accompanied by an ocean roar” and the newspaper El Siglo XIX (1845) mentioned that many people mentioned that “the water seemed to boil….” (reference #13627)

Reference #13234 (p. 268) provides a number of accounts of tsunami observations in Acapulco which include inundation of 40 m (or 50 varas) and withdrawal of 32 m (or 42 varas), with tsunami at about 4 pm local time following a 3:30 pm shaking from the earthquake.

Reference #13024 states that in Acapulco half an hour after earthquake two strong sea surges penetrated the coast of 40 m and 32 m respectively. [Note: possible that withdrawal confused with inundation]. The ebb and flow of the sea lasted several hours. Withdrawal of the sea was also reported on the coasts of Jalisco. In Michoacan, on the seashore, the earthquake was quite deafening, as the noise that could be heard was as loud or louder than a hurricane; the trees swayed in such a way that they almost touched the ground with their parts; the water seemed to boil and moved strongly