The 1979 Tumaco earthquake occurred at on 12 December with a moment magnitude 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. Surface damage Before the instrumental pe ...

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 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 ...

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

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 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, the ...

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 Mi ...

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 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 ...

, is moving to the east relative to South America at a rate of 58 mm per year. North of the Carnegie Ridge, 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 , motto = Por Guayaquil Independiente en, For Independent Guayaquil , image_map = , map_caption = , pushpin_map = Ecuador#South America , pushpin_re ...

, Esmeraldas and

Quito Quito (; qu, Kitu), formally San Francisco de Quito, is the capital city, capital and largest city of Ecuador, with an estimated population of 2.8 million in its urban area. It is also the capital of the province of Pichincha Province, Pichincha ...

) 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 period and between 1991 and 2000, is the capital city of Colombia, and one of the largest ...

Cali Santiago de Cali (), or Cali, is the capital of the Valle del Cauca department, and the most populous city in southwest Colombia, with 2,227,642 residents according to the 2018 census. The city spans with of urban area, making Cali the secon ...

Popayán Popayán () is the capital of the Colombian department of Cauca. It is located in southwestern Colombia between the Western Mountain Range and Central Mountain Range. It has a population of 318,059 people, an area of 483 km2, is located ...

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, near central Colombia, led to the development of a national building code for

earthquake-resistant structures Earthquake-resistant or aseismic structures are designed to protect buildings to some or greater extent from earthquakes. While no structure can be entirely immune to damage from earthquakes, the goal of earthquake-resistant construction is to ...

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 1979 tsunamis December 1979 events in South America Megathrust earthquakes in Colombia Megathrust earthquakes in Ecuador Tsunamis in Colombia Tsunamis in Ecuador