The 1959 Coatzacoalcos earthquake (also known as the Jáltipan earthquake) occurred at 02:25

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 ...

on August 26 near the

Mexican Mexican may refer to: Mexico and its culture *Being related to, from, or connected to the country of Mexico, in North America ** People *** Mexicans, inhabitants of the country Mexico and their descendants *** Mexica, ancient indigenous people ...

state of

Veracruz Veracruz (), formally Veracruz de Ignacio de la Llave (), officially the Free and Sovereign State of Veracruz de Ignacio de la Llave ( es, Estado Libre y Soberano de Veracruz de Ignacio de la Llave), is one of the 31 states which, along with Me ...

. The earthquake measured 6.4 at a depth of , and had a maximum Modified Mercalli intensity of VIII (''Severe''). It had an

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 ...

immediately off the coast of

Coatzacoalcos Coatzacoalcos () is a major port city in the southern part of the Mexican state of Veracruz, mostly on the western side of the Coatzacoalcos River estuary, on the Bay of Campeche, on the southern Gulf of Mexico coast. The city serves as the munic ...

(in the

Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an oceanic basin, ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of ...

). The shallow back-arc thrust faulting earthquake damaged the cities of

Acayucan Acayucan is a city in the Mexican state of Veracruz, located in the state's southeast, in the Olmeca region. It serves as the municipal seat for the Acayucan Municipality. At the 2005 INEGI Census, Acayucan reported a population of 49,945. Ref ...

, Coatzacoalcos,

Jáltipan Jáltipan is a municipality in Veracruz, Mexico. It is located in the southern part of the state of Veracruz, about 380 km from state capital Xalapa. It has a surface of 331.48 km2. It is located at . The municipality of Jáltipan is delimited ...

and Minatitlán. A total of 25 people died, including 10 from Jáltipan while a further 200 were injured. The Middle America Trench, a subduction zone that borders the southwestern coast of Mexico and Central America, accounts for much of the seismicity in Mexico. The eastern side of the country near the Gulf of Mexico rarely experiences large earthquakes although they have been recorded around the Veracruz area, where seismicity is higher compared to other parts of the gulf. Seismicity in the gulf is attributed to back-arc compression due to subduction.

Tectonic setting

Mexico is one of the most seismically active regions in the world; located at the boundary of at least three tectonic plates. The west coast of Mexico lies at a

convergent plate 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 ...

between 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 ...

and

North American Plate The North American Plate is a tectonic plate covering most of North America, Cuba, the Bahamas, extreme northeastern Asia, and parts of Iceland and the Azores. With an area of , it is the Earth's second largest tectonic plate, behind the Pacific ...

. The Cocos Plate, consisting of denser oceanic lithosphere, subducts to the northeast beneath the less dense continental crust of the North American Plate. Most of the Mexican landmass is situated on the North American plate and is moving westward. Because oceanic crust is relatively dense it subducts beneath the buoyant continental crust of the Mexican landmass. Subduction off the Pacific coast of Mexico occurs along 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 ...

along the southern coast of Mexico. The subduction zone is

seismically active An active fault is a fault (geology), fault that is likely to become the source of another earthquake sometime in the future. Geologists commonly consider faults to be active if there has been movement observed or evidence of seismic activity duri ...

and responsible for large earthquakes—a magnitude 8.1 earthquake in 1985 caused over 9,500 fatalities.

Earthquake

The earthquake had a

focal mechanism The focal mechanism of an earthquake describes the deformation in the source region that generates the seismic waves. In the case of a fault-related event it refers to the orientation of the fault plane that slipped and the slip vector and is ...

corresponding to thrust faulting at a depth of . The source fault is characterized by a high-angle

plane Plane(s) most often refers to: * Aero- or airplane, a powered, fixed-wing aircraft * Plane (geometry), a flat, 2-dimensional surface Plane or planes may also refer to: Biology * Plane (tree) or ''Platanus'', wetland native plant * ''Planes' ...

oriented parallel to the Veracruz coast. A similar earthquake in the same area in 1967 demonstrated thrust faulting mechanism at depth. In 1946, a magnitude 6.0 also struck the same place with a similar focal mechanism. These earthquakes are not associated with rupture on the subduction zone off Mexico's west coast. The focal depth of these events are unusually deep for most intracontinental earthquakes, where the depth is usually shallower than . This suggests the earthquakes occurred inside the mantle, beneath the -thick transitional crust. The Gulf of Mexico, where the Jáltipan earthquake occurred, is a region of low seismicity. This area represents a

passive margin A passive margin is the transition between oceanic and continental lithosphere that is not an active plate margin. A passive margin forms by sedimentation above an ancient rift, now marked by transitional lithosphere. Continental rifting creat ...

and is considered aseismic. At the

Isthmus of Tehuantepec The Isthmus of Tehuantepec () is an isthmus in Mexico. It represents the shortest distance between the Gulf of Mexico and the Pacific Ocean. Before the opening of the Panama Canal, it was a major overland transport route known simply as the Te ...

, intermediate-depth earthquakes associated with the subducting Cocos Plate are common. However, there is a region of shallow seismicity around Veracruz and Tabasco in the southwestern part of the gulf where earthquakes are of low magnitude. Shallow seismic activity on the

isthmus An isthmus (; ; ) is a narrow piece of land connecting two larger areas across an expanse of water by which they are otherwise separated. A tombolo is an isthmus that consists of a spit or bar, and a strait is the sea counterpart of an isthmu ...

is associated with

back-arc A back-arc basin is a type of geologic basin, found at some convergent plate boundaries. Presently all back-arc basins are submarine features associated with island arcs and subduction zones, with many found in the western Pacific Ocean. Most o ...

compression within the shallow crust. Deformation of the crust is accommodated by crustal shortening on

thrust fault A thrust fault is a break in the Earth's crust, across which older rocks are pushed above younger rocks. Thrust geometry and nomenclature Reverse faults A thrust fault is a type of reverse fault that has a dip of 45 degrees or less. If ...

s. This compressive force is brought on by west coast subduction, as well as subduction of the

Tehuantepec Ridge The Tehuantepec Ridge is a linear undersea ridge located off the west coast of Mexico in the Pacific Ocean. It is the remnant of an old fracture zone, and not a tectonic spreading center ridge (''see'' mid-ocean ridge). It extends from the easte ...

Damage

An estimated 25 people died and 200 were injured. The combined effects of structural or foundation failure and

soil liquefaction Soil liquefaction occurs when a cohesionless saturated or partially saturated soil substantially loses strength and stiffness in response to an applied stress such as shaking during an earthquake or other sudden change in stress condition, in ...

earned the earthquake a maximum

Modified Mercalli intensity The Modified Mercalli intensity scale (MM, MMI, or MCS), developed from Giuseppe Mercalli's Mercalli intensity scale of 1902, is a seismic intensity scale used for measuring the intensity of shaking produced by an earthquake. It measures the eff ...

of VIII (''Severe''). Intensity VIII was assigned in Jáltipan, Coatzacoalcos and Minatitlán, where these effects were observed. Building failures occurred at Coatzacoalcos and Minatitlán. Ground

subsidence Subsidence is a general term for downward vertical movement of the Earth's surface, which can be caused by both natural processes and human activities. Subsidence involves little or no horizontal movement, which distinguishes it from slope move ...

due to

liquefaction In materials science, liquefaction is a process that generates a liquid from a solid or a gas or that generates a non-liquid phase which behaves in accordance with fluid dynamics. It occurs both naturally and artificially. As an example of the ...

was observed at the port of Coatzacoalcos. Altogether, 450 homes and other dwellings, a school, two churches and a railroad station were total losses. Twenty five people died and 200 were injured.

was nearly destroyed—10 people were killed and 138 were injured, including 45 in serious condition. A navy workshop in Coatzacoalcos subsided by a meter, cracking its floor. Petrol storage facilities at the port were damaged. A highway and the city streets suffered cracks. The tower of the San Francisco de Asís church was severely compromised and needed to be demolished. In Minatitlán, an oil pipeline ruptured and spilled. In

, 20 percent of the city's buildings were demolished and there were 20 wounded. The highway between Coatzacoalcos and Minatitlán were filled with cracks up to wide and deep. From Santa Marta, residents reported a large flame towering over the

Sierra de los Tuxtlas The Sierra de Los Tuxtlas (Tuxtlas Mountains) are a volcanic belt and mountain range along the southeastern Veracruz Gulf coast in Eastern Mexico. The Los Tuxtlas Biosphere Reserve (Biósfera Los Tuxtlas) includes the coastal and higher elevations ...

range.

Aftermath

Volunteers rushed to the

fire brigade A fire department (American English) or fire brigade (Commonwealth English), also known as a fire authority, fire district, fire and rescue, or fire service in some areas, is an organization that provides fire prevention and fire suppression se ...

in response to those injured and to remove bodies from the rubble. Ambulances from Red Cross organizations arrived shortly. The Governor of Veracruz, Antonio Modesto Quirasco, along with members of his cabinet, arrived at Jáltipan on the night of August 26. An establishment (Patronato Pro Recuperación Social de Jáltipan) was formed to help raise funds for the reconstruction of Jáltipan. The representative of President

Adolfo López Mateos Adolfo López Mateos (; 26 May 1909 – 22 September 1969) was a Mexican politician who served as President of Mexico from 1958 to 1964. Beginning his political career as a campaign aide of José Vasconcelos during his run for president, Lóp ...

, Fernando López Arias, arrived the following day to overlook and manage reconstruction projects. Many

socialite A socialite is a person from a wealthy and (possibly) aristocratic background, who is prominent in high society. A socialite generally spends a significant amount of time attending various fashionable social gatherings, instead of having traditio ...

s contributed to food distribution.

References

External links

* {{Earthquakes in Mexico 1959 earthquakes Earthquakes in Mexico History of Veracruz 1959 in Mexico August 1959 events in North America History of the Gulf of Mexico Gulf of Mexico 1959 disasters in Mexico