The 1979 Tumaco earthquake occurred at on 12 December with a

moment magnitude The moment magnitude scale (MMS; denoted explicitly with or Mwg, and generally implied with use of a single M for magnitude) is a measure of an earthquake's magnitude ("size" or strength) based on its seismic moment. was defined in a 1979 paper ...

of 8.2 and a maximum Mercalli intensity of IX (''Violent''). The

epicenter The epicenter (), epicentre, or epicentrum in seismology is the point on the Earth's surface directly above a hypocenter or focus, the point where an earthquake or an underground explosion originates. Determination The primary purpose of a ...

was just offshore from the border between Ecuador and Colombia, near the port city of

Tumaco Tumaco is a port city and municipality in the Nariño Department, Colombia, by the Pacific Ocean. It is located on the southwestern corner of Colombia, near the border with Ecuador, and experiences a hot tropical climate. Tumaco is inhabited main ...

. It 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, ...

, which was responsible for most of the estimated 300–600 deaths. The hardest hit area was Colombia's

Nariño Department Nariño () is a department of Colombia named after independence leader Antonio Nariño. Its capital is Pasto. It is in the west of the country, bordering Ecuador and the Pacific Ocean. Nariño has a diverse geography and varied climate acc ...

Tectonic setting

Coastal parts of Ecuador and southern Colombia lie above the

convergent boundary A convergent boundary (also known as a destructive boundary) is an area on Earth where two or more lithospheric plates collide. One plate eventually slides beneath the other, a process known as subduction. The subduction zone can be defined by a ...

where the Malpelo plate

subducts Subduction is a geological process in which the oceanic lithosphere and some continental lithosphere is recycled into the Earth's mantle at the convergent boundaries between tectonic plates. Where one tectonic plate converges with a second pla ...

beneath the

South American plate The South American plate is a major tectonic plate which includes the continent of South America as well as a sizable region of the Atlantic Ocean seabed extending eastward to the African plate, with which it forms the southern part of the Mid ...

along the Colombia–Ecuador Trench. At this location the Malpelo plate, the microplate northeast of the

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

, is moving to the east relative to South America at a rate of 58 mm per year. North of the

Carnegie Ridge The Carnegie Ridge is an aseismic ridge on the Nazca plate that is being Subduction, subducted beneath the South American plate. The ridge is thought to be a result of the passage of the Nazca Plate over the Galápagos hotspot. It is named for th ...

, the subduction interface has four recognisable segments, from south to north, the Esmeraldas, Manglares, Tumaco and Patia segments. This plate boundary has been the location of several great historical earthquakes, most associated with damaging tsunamis. In 1906, a 5–600 km long segment of the plate interface ruptured, causing a M 8.8 earthquake (rupturing all four segments) and a trans-Pacific tsunami.

Earthquake

This event was the last of three earthquakes that ruptured adjacent parts of the plate interface, forming a northeastward migrating sequence. The 1942 earthquake ruptured the Esmeraldas segment, the 1958 earthquake ruptured the Manglares segment and the 1979 event ruptured the Tumaco and Patia segments. Together they ruptured the same part of the megathrust as the 1906 earthquake. The rupture area of the 1979 earthquake measured 280 km long by 130 km wide. The earthquake was widely felt in both Ecuador (including

Guayaquil Guayaquil (), officially Santiago de Guayaquil, is the largest city in Ecuador and also the nation's economic capital and main port. The city is the capital (political), capital of Guayas Province and the seat of Guayaquil Canton. The city is ...

, Esmeraldas and

Quito Quito (; ), officially San Francisco de Quito, is the capital city, capital and second-largest city of Ecuador, with an estimated population of 2.8 million in its metropolitan area. It is also the capital of the province of Pichincha Province, P ...

) and Colombia (including

Bogotá Bogotá (, also , , ), officially Bogotá, Distrito Capital, abbreviated Bogotá, D.C., and formerly known as Santa Fe de Bogotá (; ) during the Spanish Imperial period and between 1991 and 2000, is the capital city, capital and largest city ...

Cali Santiago de Cali (), or Cali, is the capital of the Valle del Cauca department, and the most populous city in southwest Colombia, with 2,280,522 residents estimate by National Administrative Department of Statistics, DANE in 2023. The city span ...

Popayán Popayán () is the capital of the Colombian department of Cauca. It is located in the Pubenza Valley in southwestern Colombia between the Western Mountain Range and Central Mountain Range. The municipality has a population of 318,059, an a ...

and Buenaventura). The coast in the epicentral region subsided by up to 1.6 m during the earthquake and the land movement locally disrupted river drainage.

Tsunami

The coast nearest the epicenter was hit by the first wave of the tsunami about three minutes after the earthquake. Three to four waves were observed, with the third being the highest. The third wave coincided with low tide, greatly reducing the extent of the inundation and the likely death toll. The maximum observed water height was 6.0 m at San Juan de la Costa, northeast of Tumaco. The tsunami was observed on the east coast of Japan, in Hawaii, Tahiti and Mexico.

Damage

The earthquake caused widespread damage, particularly in Tumaco, where about a tenth of all buildings were destroyed, including 1,280 houses, and 25 people were reported either dead or missing. The fishing village of Charco was almost completely destroyed by the tsunami, the waves washing the houses inland into a nearby lake. 93 of the original population of 4,000 were reported either dead or missing. The tsunami also destroyed all the houses in San Juan de la Costa, with 199 reported either dead or missing. The total death toll was estimated to be 500–600 with another 4,000 injured.

Aftermath

The damage caused by this earthquake and the

1983 Popayán earthquake 1983 saw both the official beginning of the Internet and the first mobile cellular telephone call. Events January * January 1 – The migration of the ARPANET to TCP/IP is officially completed (this is considered to be the beginning of the ...

, near central Colombia, led to the development of a national building code for earthquake-resistant structures for Colombia, which came into law in 1984.

References

External links

* {{Portal bar, Ecuador, Colombia, Earth sciences 1979 earthquakes 1979 in Colombia 1979 in Ecuador 1970s tsunamis December 1979 in South America Megathrust earthquakes in Colombia Megathrust earthquakes in Ecuador Tsunamis in Colombia Tsunamis in Ecuador