1868 Arica earthquake

Tectonic setting

The earthquake occurred along the boundary between the Nazca plate and the South American plate. The earthquake was likely a result of thrust-faulting, caused by the subduction of the Nazca plate beneath the South American plate.

The coasts of Peru and Chile have a history of great megathrust earthquakes originating from this plate boundary, such as the 1960 Valdivia earthquake and the 2010 Chile earthquake.

Damage

The earthquake caused almost complete destruction in the southern part of Peru, including Arica, Tacna, Moquegua, Mollendo, Ilo, Iquique, Torata and Arequipa, resulting in an estimated 25,000 casualties, and many shipwrecks.

The tsunami drove three ships anchored in port nearly 800 m inland: the 1,560-ton Peruvian corvette , the U.S. gunboat Wateree and the U.S. store ship , which was completely destroyed. The brig Chañarcillo and two schooners, Rosa Rivera and Regalon, were also lost. Okal et al. (2006) suggested that the tsunami also severely affected the port city of Pisco, although later studies have regarded this as weak evidence, instead concluding that Pisco and Callao likely experienced only mild inundation.

The tsunami caused considerable damage in Hawaii, washing out a bridge along the Waiohi River. In New Zealand, it is the only fatal tsunami on record, causing substantial damage on the Chatham Islands and an estimated 20 people washed out to sea. On the mainland, Banks Peninsula was hardest hit with a Maori village and two houses washed away and boats damaged, and one death was recorded.

Characteristics

Earthquake

Two separate earthquakes have been described; they may both refer to the same event.

The earthquake was felt over a wide area, up to 1400 km to the northwest in Samanco, Peru and 224 km to the east in Bolivia.

Estimates of its magnitude have varied. Okal et al. (2006) suggested a broad range of 8.5–9.3 based on tsunami modeling. However, Carvajal et al. (2025), using trans-Pacific tide gauge records from the United States and Australia together with tsunami modeling, argued that a narrower range of 8.8–9.1 is more plausible, and that the lower and upper extremes of earlier estimates are unlikely. A rupture length of about 600 km has been inferred from the pattern of isoseismals, making it one of the largest fault breaks in modern times.

About 400 aftershocks were recorded by 25 August of that year.

Contemporary accounts say that the earthquake shaking lasted somewhere between five and ten minutes.

Tsunami

Although this event generated a tsunami that was noted across the Pacific, most of the associated damage was localised along the coasts of southern Peru and what is now northernmost Chile. The first wave arrived at Arica 52 minutes after the earthquake, with a 12 m height, followed by the largest 16 m wave 73 minutes later.

Future risk

In 2001, the Arica area was identified as forming part of a seismic gap between 15° and 24°S, with no major earthquake since 1877. In accordance with this theory, a major earthquake was considered likely to happen in the near future. More specifically, in 2005, a magnitude 8.6 event was forecast for the northern Chile part of the gap, the location of the subsequent 2014 Iquique earthquake. An earthquake affecting the same sector of the plate boundary as the 1868 event with a magnitude of 8.8 was also forecast as likely to occur by 2126. A repeat of the 1868 event would probably cause more casualties, because of the increase of population in areas at risk.

References

References

1. IISEE. "Catalog of Damaging Earthquakes in the World (Through 2007)".
2. (2025). "Large Size of Two 19th-Century Chile-Peru Earthquakes Inferred From Trans-Pacific Tsunami Records". Geophysical Research Letters.
3. Okal, E.A.. (2006). "Evaluation of Tsunami Risk from Regional Earthquakes at Pisco, Peru". Bulletin of the Seismological Society of America.
4. (26 October 2009). "Arica, Peru (now Chile) 1868 August 13 21:30 UTC". United States Geological Survey.
5. [http://paperspast.natlib.govt.nz/cgi-bin/paperspast?a=d&cl=search&d=TS18680829.2.13&srpos=160&e=13-08-1868-----10--151-byDA---0wave-ARTICLE- Latest from Australia], ''Star'', Issue 92, 29 August 1868, Page 3
6. Zamudio, Y.. (2005). "Seismic hazard assessment in the Peru-Chile border region". 6th International Symposium on Andean Geodynamics.
7. Allen, G.W.. (April 1869). "The Great South American Earthquakes of 1868".
8. Morton, Jamie. (13 August 2018). "NZ's only killer tsunami: What it means today". The New Zealand Herald.
9. (13 August 2018). "Only deadly NZ tsunami on record hit the Chathams, 150 years ago".
10. [http://paperspast.natlib.govt.nz/cgi-bin/paperspast?a=d&cl=search&d=ODT18680828.2.18&srpos=147&e=13-08-1868-----10--141-byDA---0wave-ARTICLE- "Arrival of the schooner ''Rifleman'' from the Chatham Islands"], ''Otago Daily Times'', Issue 2048, 28 August 1868, p. 3
11. National Geophysical Data Center / World Data Service (NGDC/WDS): NCEI/WDS Global Significant Earthquake Database. NOAA National Centers for Environmental Information.. (1972). "Significant Earthquake Information". NOAA National Centers for Environmental Information.
12. Rabinovich, A.B.. (2001). "Tsunami risk estimation for the coasts of Peru and northern Chile". ITS 2001 Proceedings, Session 1.