The 1730 Valparaíso earthquake occurred at 04:45 local time (08:45

UTC Coordinated Universal Time (UTC) is the primary time standard globally used to regulate clocks and time. It establishes a reference for the current time, forming the basis for civil time and time zones. UTC facilitates international communica ...

) on July 8. It had an estimated

magnitude Magnitude may refer to: Mathematics *Euclidean vector, a quantity defined by both its magnitude and its direction *Magnitude (mathematics), the relative size of an object *Norm (mathematics), a term for the size or length of a vector *Order of ...

of 9.1–9.3 and triggered a major

tsunami A tsunami ( ; from , ) 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 (including detonations, ...

with an estimated

of 8.75, that inundated the lower parts of

Valparaíso Valparaíso () is a major city, Communes of Chile, commune, Port, seaport, and naval base facility in the Valparaíso Region of Chile. Valparaíso was originally named after Valparaíso de Arriba, in Castilla–La Mancha, Castile-La Mancha, Spain ...

. The earthquake caused severe damage from La Serena to Chillan, while the tsunami affected more than of

Chile Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, stretching along a narrow strip of land between the Andes, Andes Mountains and the Paci ...

's coastline.

Tectonic setting

The earthquake took place along the boundary between the Nazca and

South American South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

tectonic plates Plate tectonics (, ) is the scientific theory that the Earth's lithosphere comprises a number of large tectonic plates, which have been slowly moving since 3–4 billion years ago. The model builds on the concept of , an idea developed durin ...

, at a location where they

converge Converge may refer to: * Converge (band), American hardcore punk band * Converge (Baptist denomination), American national evangelical Baptist body * Limit (mathematics) In mathematics, a limit is the value that a function (or sequence) app ...

at a rate of seventy millimeters a year. Chile has been at a convergent plate boundary that generates

megathrust earthquake Megathrust earthquakes occur at convergent plate boundaries, where one tectonic plate is forced underneath another. The earthquakes are caused by slip along the thrust fault that forms the contact between the two plates. These interplate earthq ...

s since the

Paleozoic The Paleozoic ( , , ; or Palaeozoic) Era is the first of three Era (geology), geological eras of the Phanerozoic Eon. Beginning 538.8 million years ago (Ma), it succeeds the Neoproterozoic (the last era of the Proterozoic Eon) and ends 251.9 Ma a ...

(500 million years ago). In historical times the Chilean coast has suffered many megathrust earthquakes along this plate boundary, including the strongest earthquake ever measured. Most recently, the boundary ruptured in 2010 in central Chile.

Damage

The earthquake caused severe damage over a wide area,

Coquimbo Coquimbo is a port List of cities in Chile, city, Communes of Chile, commune and capital of the Elqui Province, located on the Pan-American Highway, in the Coquimbo Region of Chile. Coquimbo is situated in a valley south of La Serena, Chile, La S ...

Illapel Illapel () is a Chilean city, which is the capital of the Choapa Province, Coquimbo Region. It lies along the Illapel River and marks the country's narrowest point along a parallel (94 km). It is located to the east of Los Vilos. Admini ...

, Petorca and Tiltil were all affected. The parish church in La Serena was destroyed. Only a few deaths were recorded due to the earthquake, reportedly because a strong

foreshock A foreshock is an earthquake that occurs before a larger seismic eventthe mainshockand is related to it in both time and space. The designation of an earthquake as ''foreshock'', ''mainshock'' or aftershock is only possible after the full sequenc ...

had caused people to leave their homes. The same is also true for the following tsunami with the inhabitants running to higher ground after seeing the water recede, so that only a few were killed.

Characteristics

Earthquake

At about 01:00 local time in

Santiago Santiago (, ; ), also known as Santiago de Chile (), is the capital and largest city of Chile and one of the largest cities in the Americas. It is located in the country's central valley and is the center of the Santiago Metropolitan Regi ...

, there was a strong earthquake, followed by several smaller tremors. The main shock occurred at 4:45 local time. A long rupture has been estimated for this event, from the extent of severe damage.

Tsunami

The tsunami occurred immediately after the mainshock, with a maximum run-up height recorded at Concepción of 16 m. It was also observed at

Callao Callao () is a Peruvian seaside city and Regions of Peru, region on the Pacific Ocean in the Lima metropolitan area. Callao is Peru's chief seaport and home to its main airport, Jorge Chávez International Airport. Callao municipality consists ...

Peru Peru, officially the Republic of Peru, is a country in western South America. It is bordered in the north by Ecuador and Colombia, in the east by Brazil, in the southeast by Bolivia, in the south by Chile, and in the south and west by the Pac ...

and in

Honshu , historically known as , is the largest of the four main islands of Japan. It lies between the Pacific Ocean (east) and the Sea of Japan (west). It is the list of islands by area, seventh-largest island in the world, and the list of islands by ...

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

where fields were flooded in Rikuzen and the

Oshika Peninsula The also pronounced "Ojika" is a peninsula which projects southeast into the Pacific Ocean from the coast of Miyagi Prefecture in northeast Honshu, the main island of Japan. The peninsula is most often visited as the gateway to the island of Kin ...

References