The 8.5–9.0 Mw  Arica earthquake struck southern Peru with a maximum Mercalli intensity of XI (Extreme), causing 25,000+ deaths and a destructive basin wide tsunami that affected Hawaii and New Zealand.

The 1868 Arica earthquake occurred on 13 August 1868, near Arica, then part of Peru, now part of Chile, at 21:30 UTC. It had an estimated magnitude between 8.5 and 9.3. A tsunami in the Pacific Ocean was produced by the earthquake, which was recorded in Hawaii, Japan, Australia, and New Zealand.

Peru, officially the Republic of Peru, is a country in western South America. It is bordered to the north by Ecuador and Colombia, to the east by Brazil, to the southeast by Bolivia, to the south by Chile, and to the south and west by the Pacific Ocean. Peru is a megadiverse country, with habitats ranging from the arid plains of the Pacific coastal region in the west, to the peaks of the Andes mountains extending from the north to the southeast of the country, to the tropical Amazon basin rainforest in the east with the Amazon River. Peru has a population of over 32 million, and its capital and largest city is Lima. At 1,285,216 km² (496,225 sq mi), Peru is the 19th largest country in the world, and the third largest in South America.

The Modified Mercalli intensity scale measures the effects of an earthquake at a given location. This is in contrast with the seismic magnitude usually reported for an earthquake.

A tsunami is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Earthquakes, volcanic eruptions and underwater explosions above or below water all have the potential to generate a tsunami. Unlike normal ocean waves, which are generated by wind, or tides, which are in turn generated by the gravitational pull of the Moon and the Sun, a tsunami is generated by the displacement of water from a large event.