The Riobamba earthquake strikes Ecuador, causing up to 40,000 casualties.

The 1797 Riobamba earthquake occurred at 12:30 UTC on 4 February. It devastated the city of Riobamba and many other cities in the Interandean valley, causing between 6,000 and 40,000 casualties. It is estimated that seismic intensities in the epicentral area reached at least XI (Extreme) on the Mercalli intensity scale, and that the earthquake had a magnitude of 7.6–8.3, the most powerful historical event known in Ecuador. The earthquake was studied by Prussian geographer Alexander von Humboldt, when he visited the area in 1801–1802.

Ecuador, officially the Republic of Ecuador, is a country in northwestern South America, bordered by Colombia on the north, Peru on the east and south, and the Pacific Ocean on the west. It also includes the Galápagos Province which contains the Galápagos Islands in the Pacific, about 1,000 kilometers (621 mi) west of the mainland. The country's capital is Quito and its largest city is Guayaquil.

February 4 is the 35th day of the year in the Gregorian calendar; 330 days remain until the end of the year.