The 1917 San Salvador earthquake occurred on June 7 at 18:55

local time Local time is the time observed in a specific locality. There is no canonical definition. Originally it was mean solar time, but since the introduction of time zones it is generally the time as determined by the time zone in effect, with daylight s ...

near the

Salvadoran Salvadorans (Spanish: ''Salvadoreños''), also known as Salvadorians (alternate spelling: Salvadoreans), are citizens of El Salvador, a country in Central America. Most Salvadorans live in El Salvador, although there is also a significant Salvado ...

capital. The

hypocenter In seismology, a hypocenter or hypocentre () is the point of origin of an earthquake or a subsurface nuclear explosion. A synonym is the focus of an earthquake. Earthquakes An earthquake's hypocenter is the position where the strain energy s ...

of the 6.7 was at a shallow depth of , and occurred along a shallow crustal fault near

San Salvador San Salvador (; ) is the capital and the largest city of El Salvador and its eponymous department. It is the country's political, cultural, educational and financial center. The Metropolitan Area of San Salvador, which comprises the capital i ...

. The earthquake caused significant destruction of the city and left approximately 1,050 dead. It was followed by an eruption on

that killed another 1,100. Only behind the earthquake of

1986 The year 1986 was designated as the International Year of Peace by the United Nations. Events January * January 1 ** Aruba gains increased autonomy from the Netherlands by separating from the Netherlands Antilles. **Spain and Portugal ente ...

, it is the second deadliest in El Salvador's history.

Earthquake

El Salvador lies atop the

Chortis Block The Chortis Block is a -wide continental fragment in Central America ( Honduras, Nicaragua, El Salvador, Guatemala, and the off-shore Nicaragua Rise) located in the northwest corner of the oceanic Caribbean Plate. Extent The northern margin of ...

, near its western margin. It is bounded by the

Motagua The Motagua River () is a river in Guatemala. It rises in the western highlands of Guatemala where it is also called Río Grande, and runs in an easterly direction to the Gulf of Honduras. The final few kilometres of the river form part of the ...

– Polochic Fault between the

North American North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Ca ...

–

Caribbean The Caribbean (, ) ( es, El Caribe; french: la Caraïbe; ht, Karayib; nl, De Caraïben) is a region of the Americas that consists of the Caribbean Sea, its islands (some surrounded by the Caribbean Sea and some bordering both the Caribbean Se ...

transform boundary A transform fault or transform boundary, is a fault along a plate boundary where the motion is predominantly horizontal. It ends abruptly where it connects to another plate boundary, either another transform, a spreading ridge, or a subductio ...

. Along the western margin, at the

Middle America Trench The Middle America Trench is a major subduction zone, an oceanic trench in the eastern Pacific Ocean off the southwestern coast of Middle America, stretching from central Mexico to Costa Rica. The trench is 1,700 miles (2,750 km) long an ...

, the

Cocos Plate The Cocos Plate is a young oceanic tectonic plate beneath the Pacific Ocean off the west coast of Central America, named for Cocos Island, which rides upon it. The Cocos Plate was created approximately 23 million years ago when the Farallon Plate ...

subduct 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 ...

s beneath it at /year. Subduction produces volcanism along the

Central America Volcanic Arc The Central American Volcanic Arc (often abbreviated to CAVA) is a chain of volcanoes which extends parallel to the Pacific coastline of the Central American Isthmus, from Mexico to Panama. This volcanic arc, which has a length of 1,100 kilometer ...

(CAVA) which stretches from

Costa Rica Costa Rica (, ; ; literally "Rich Coast"), officially the Republic of Costa Rica ( es, República de Costa Rica), is a country in the Central American region of North America, bordered by Nicaragua to the north, the Caribbean Sea to the no ...

Guatemala Guatemala ( ; ), officially the Republic of Guatemala ( es, República de Guatemala, links=no), is a country in Central America. It is bordered to the north and west by Mexico; to the northeast by Belize and the Caribbean; to the east by H ...

. Within the shallow crust of El Salvador, seismicity is associated with the El Salvador Fault Zone (ESFZ), a

shear zone In geology, a shear zone is a thin zone within the Earth's crust or upper mantle that has been strongly deformed, due to the walls of rock on either side of the zone slipping past each other. In the upper crust, where rock is brittle, the shear ...

. The ESFZ is located within the CAVA, measuring in length and across. The ESFZ consists of strike-slip and normal faults which have produced large destructive earthquakes in 1917, 1919,

1965 Events January–February * January 14 – The Prime Minister of Northern Ireland and the Taoiseach of the Republic of Ireland meet for the first time in 43 years. * January 20 ** Lyndon B. Johnson is Second inauguration of Lyndo ...

and

2001 The September 11 attacks against the United States by Al-Qaeda, which Casualties of the September 11 attacks, killed 2,977 people and instigated the global war on terror, were a defining event of 2001. The United States led a Participants in ...

. One of these faults, the Guaycume Fault, may have been the source of the earthquake. A slip rate of /yr was suggested along the fault, one of the most dangerous in El Salvador due to its closeness to San Salvador. Another possible source is a fault running beneath the San Salvador volcano that ruptured. The earthquake measured a

moment magnitude The moment magnitude scale (MMS; denoted explicitly with or Mw, 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. It was defined in a 1979 pape ...

of 6.7 and

surface-wave magnitude The surface wave magnitude (M_s) scale is one of the magnitude scales used in seismology to describe the size of an earthquake. It is based on measurements of Rayleigh surface waves that travel along the uppermost layers of the Earth. This ma ...

of 6.5 . About 30 minutes later, a 6.3 earthquake struck nearby, beneath the San Salvador volcano. An aftershock of 6.0 occurred in 1919.

Impact

The Colombian poet,

Porfirio Barba-Jacob Miguel Ángel Osorio Benítez (July 29, 1883 – January 14, 1942), better known by his pseudonym, Porfirio Barba-Jacob, was a Colombian poet and writer. Born in Santa Rosa de Osos, Antioquia, to parents Antonio María Osorio and Pastora B ...

, recorded a total of 1,050 fatalities and many injured. In the towns of

Armenia Armenia (), , group=pron officially the Republic of Armenia,, is a landlocked country in the Armenian Highlands of Western Asia.The UNbr>classification of world regions places Armenia in Western Asia; the CIA World Factbook , , and ''Ox ...

and Quezaltepeque, 40 people were killed and over 100 were injured. Damage in San Salvador was severe; described as "80 out of every 100 homes were razed". The business district of San Salvador was incinerated by fires. The large fires killed an estimated 100 people. Residents failed to douse the flames as the city's water systems were wrecked. Out of the 9,000 homes in San Salvador, only 200 remained standing. All government buildings with the exception of the national theater and palace withstood the earthquake. Hospitals, university buildings, schools, and other public structures were razed. The town of Santa Tecla and other nearby communities were levelled. Surviving buildings eventually toppled during the second major earthquake at 19:30. In addition to damaged buildings, the local

coffee plantation A plantation is an agricultural estate, generally centered on a plantation house, meant for farming that specializes in cash crops, usually mainly planted with a single crop, with perhaps ancillary areas for vegetables for eating and so on. The ...

s were ruined.

San Salvador eruption

The San Salvador volcano erupted about 35 minutes after the 6.3 earthquake. A

fissure A fissure is a long, narrow crack opening along the surface of Earth. The term is derived from the Latin word , which means 'cleft' or 'crack'. Fissures emerge in Earth's crust, on ice sheets and glaciers, and on volcanoes. Ground fissure A ...

was observed at 20:11 along the volcanic slope. Smoke bellowed from the fissure and lava was seen. An ash cloud was produced and accompanied by an -long

lava flow Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or und ...

along the northern slopes. An estimated of lava and scoria was ejected. The eruption was the largest since 1671, but was still considered small in size. It may have been triggered by the earthquakes disrupting plumbing within the

magma chamber A magma chamber is a large pool of liquid rock beneath the surface of the Earth. The molten rock, or magma, in such a chamber is less dense than the surrounding country rock, which produces buoyant forces on the magma that tend to drive it upw ...

. The lava flows destroyed homes and buried the railway tracks between Quezaltepeque and Sitio del Niño. The site of the eruption and its lava flows are known as Los Chintos. The eruption caused the Boquerón crater lake to evaporate and form a

cinder cone A cinder cone (or scoria cone) is a steep conical hill of loose pyroclastic fragments, such as volcanic clinkers, volcanic ash, or scoria that has been built around a volcanic vent. The pyroclastic fragments are formed by explosive eruptions o ...

in the crater named Boqueroncito—it ejected material up to high. Approximately 1,100 people were killed, including 500 who perished when they were caught in the lava flows. At least 200 people died from the

pyroclastic flow A pyroclastic flow (also known as a pyroclastic density current or a pyroclastic cloud) is a fast-moving current of hot gas and volcanic matter (collectively known as tephra) that flows along the ground away from a volcano at average speeds of bu ...

s while a further 100 died from

lahar A lahar (, from jv, ꦮ꧀ꦭꦲꦂ) is a violent type of mudflow or debris flow composed of a slurry of pyroclastic material, rocky debris and water. The material flows down from a volcano, typically along a river valley. Lahars are extreme ...

s. On 10 June, 300 residents were killed by another lava flow. The eruption rated a 3 on the Volcanic explosivity index.

Aftermath

The book '' El terremoto de San Salvador: narración de un superviviente'' (''The San Salvador Earthquake: A Survivor's Narrative'') written by Porfirio Barba-Jacob documents the events of 1917.

Earthquake

Impact

San Salvador eruption

Aftermath

See also

References

Further reading