The 1868 Arica earthquake occurred on 13 August 1868, near Arica, then part of

Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = National seal , national_motto = "Firm and Happy f ...

, now part of

Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the eas ...

, at 21:30 UTC. It had an estimated magnitude between 8.5 and 9.3. A

tsunami A tsunami ( ; from ja, 津波, lit=harbour wave, ) 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 other underwater exp ...

(or multiple tsunamis) in the

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the conti ...

was produced by the earthquake, which was recorded in

Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only stat ...

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the n ...

Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...

, and

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island coun ...

Tectonic setting

The earthquake occurred along the boundary between the

Nazca Plate The Nazca Plate or Nasca Plate, named after the Nazca region of southern Peru, is an oceanic tectonic plate in the eastern Pacific Ocean basin off the west coast of South America. The ongoing subduction, along the Peru–Chile Trench, of the N ...

and the South American Plate. The earthquake was likely a result of thrust-faulting, caused by the

subduction Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, ...

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 Tacna is a city in southern Peru and the regional capital of the Tacna Region. A very commercially active city, it is located only north of the border with Arica y Parinacota Region from Chile, inland from the Pacific Ocean and in the valley of ...

Moquegua Moquegua (, founded by the Spanish colonists as Villa de Santa Catalina de Guadalcázar del Valle de Moquegua) is a city in southern Peru, located in the Department of Moquegua, of which it is the capital. It is also capital of Mariscal Nieto P ...

Mollendo Mollendo is a town bordering the Pacific Ocean in southern Peru. It is located in the Arequipa Region and is the capital of both the Islay Province and the Mollendo District. Mollendo was the main port in the Peruvian southern coast until Matara ...

Ilo The International Labour Organization (ILO) is a United Nations agency whose mandate is to advance social and economic justice by setting international labour standards. Founded in October 1919 under the League of Nations, it is the first and ol ...

, Iquique, Torata and

Arequipa Arequipa (; Aymara and qu, Ariqipa) is a city and capital of province and the eponymous department of Peru. It is the seat of the Constitutional Court of Peru and often dubbed the "legal capital of Peru". It is the second most populated city ...

, resulting in an estimated 25,000 casualties, and many shipwrecks. The tsunami drove three ships anchored in port nearly inland: the 1560-ton Peruvian

corvette A corvette is a small warship. It is traditionally the smallest class of vessel considered to be a proper (or " rated") warship. The warship class above the corvette is that of the frigate, while the class below was historically that of the slo ...

, the U.S. gunboat ''Wateree'' and the U.S. store ship , which was completely destroyed. The

brig A brig is a type of sailing vessel defined by its rig: two masts which are both square-rigged. Brigs originated in the second half of the 18th century and were a common type of smaller merchant vessel or warship from then until the latter part ...

''Chañarcillo'' and two

schooner A schooner () is a type of sailing vessel defined by its rig: fore-and-aft rigged on all of two or more masts and, in the case of a two-masted schooner, the foremast generally being shorter than the mainmast. A common variant, the topsail schoo ...

s, ''Rosa Rivera'' and ''Regalon'', were also lost. The port city of Pisco was razed. 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 The Chatham Islands ( ) (Moriori: ''Rēkohu'', 'Misty Sun'; mi, Wharekauri) are an archipelago in the Pacific Ocean about east of New Zealand's South Island. They are administered as part of New Zealand. The archipelago consists of about t ...

and an estimated 20 people washed out to sea. On the mainland,

Banks Peninsula Banks Peninsula is a peninsula of volcanic origin on the east coast of the South Island of New Zealand. It has an area of approximately and encompasses two large harbours and many smaller bays and coves. The South Island's largest city, ...

was hardest hit with a Maori village and two houses washed away and boats damaged, and one death was recorded.Arrival of the schooner Rifleman from the Chatham Islands
Otago Daily Times, Issue 2048, 28 August 1868, Page 3

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 to the northwest in Samanco, Peru and to the east in

Bolivia , image_flag = Bandera de Bolivia (Estado).svg , flag_alt = Horizontal tricolor (red, yellow, and green from top to bottom) with the coat of arms of Bolivia in the center , flag_alt2 = 7 × 7 square p ...

. Estimates of its magnitude range from 8.5 to 9.3. A rupture length has been estimated from the pattern of isoseismals making it one of the largest fault breaks in modern times. About 400

aftershock In seismology, an aftershock is a smaller earthquake that follows a larger earthquake, in the same area of the main shock, caused as the displaced crust adjusts to the effects of the main shock. Large earthquakes can have hundreds to thousa ...

s 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 height, followed by the largest 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

External links

{{DEFAULTSORT:1868 Arica Earthquake Arica Megathrust earthquakes in Peru Megathrust earthquakes in Chile E Arica earthquake Arica earthquake 1868 tsunamis Arica Arica Arica Earthquake Tsunamis in New Zealand August 1868 events 1868 disasters in South America