1976 Guatemala earthquake

Seismic data

The quake's epicentre was located near the town of Los Amates, in the eastern part of the Motagua Fault, a left-lateral strike-slip fault that forms part of the tectonic boundary between the North American plate and the Caribbean plate. Ground shaking was felt during approximately 39 seconds, and caused visible rupturing over 230 km along the Motagua fault, while the inferred length of faulting—based on aftershock registration—was estimated at 300 km. Average horizontal displacement along the Motagua fault was 100 cm with a maximum displacement of 326 cm.

Maximum seismic intensity (MMI IX) was located in the Mixco area, some sections of Guatemala City and in Gualán. A seismic intensity of MM VI covered an area of 33,000 km2. Soil liquefaction and sand boils were observed in several locations with high seismic intensity. The main quake activated secondary fault zones, including the Mixco fault, located in a densely populated area just north-west of Guatemala City.

Victims and damage

The most heavily affected area covered some 30,000 km2, with a population of 2.5 million. In addition to the 23,000 reported fatalities and injuries to 77,000 people, approximately 258,000 houses were destroyed, leaving about 1.2 million people homeless. 40% of the national hospital infrastructure was destroyed, while other health facilities also suffered substantial damage.

International reaction

Immediately after the earthquake, President Kjell Eugenio Laugerud García invited most of the foreign ambassadors to tour the affected regions by helicopter, which prompted them to quickly ask for help in their home countries. For example, the United States of America rebuilt most of the roads, and Canada and Belgium each rebuilt a village.

Within days of the initial rupture the USGS sent a team of geologist to document the fault rupture and its effects. This team headed by George Plafker traveled the entire length of the fault by helicopter and was able to clearly trace its location. During this expedition several thousand photographs were collected including 1:10,000 aerial photographs collected by plane. In 2021 this analog data was digitized and georeferenced in order to build a database to assist in relocating the initial rupture location. During the summer of 2021 a team of geologist successfully relocated the fault rupture at 10 different locations. At the locations no evidence of post 1976 fault creep was observed.2021, McEnaney T., and Niemi, T.M., Building a georeferenced database for the 1976 Guatemalan Earthquake rupture of the Motagua fault system along the North American- Caribbean Plate Boundary: Geological Society of America Abstracts with Programs, v. 53, no. 6, https://doi.org/10.1130/abs/2021AM-370687

Aftershocks

Several aftershocks, ranging from 5.2 to 5.8 caused additional casualties and hampered relief efforts.

Source: Wayerly Person, William Spence, and James W. Dewey. Main event and principal aftershocks from teleseismic data. In: Guatemalan Earthquake of February 4, 1976, A Preliminary Report.

In popular culture

Scenes of the earthquake's aftermath, filmed on February 6, 1976, were featured in the Italian Mondo film Savana violenta, directed by Antonio Climati and Mario Morra.

Image gallery

Image:GuateQuake1976HotelTerminalA.jpg|Hotel Terminal Image:GuateQuake1976CiudadFoundationFailures.jpg|Landslide in Guatemala City Image:GuateQuake1976Ciudad50.jpg|Guatemala City centre

File:Companiadejesus.jpg|Society of Jesus church ruins in 1896. File:La Compania de Jesus.jpg|Jesuit church façade, stabilized in the 21st century. Note the damage to the structure after the 1976 earthquake. File:Señoradelcarmen.jpg|"Nuestra Señora del Carmen" Church in 1896. File:Iglesia_del_Carmen_(3746568616).jpg|Same church in 2010, after the 1976 earthquake. File:Recoleccion1875a.jpg|Iglesia de La Recolección in 1875. The only surviving arch was a symbol of Antigua Guatemala ruins for many years. File:LaRecoleccion.Antigua.jpg|La Recolección in 2005. The 1917 and 1976 earthquakes destroyed what was left of the iconic arch.

Image:GuateQuake1976BentRailsA.jpg|Bent rails in Gualán Image:Guatemala1976Earthquake14ct.jpg|Motagua Fault in Gualán Image:GuateQuake1976Patzicia.jpg|Patzicía destroyed File:Puente de Agua Caliente - on road to Coban.jpg|Puente de Agua Caliente, on the road to Cobán

Notes

References

References

1. [https://earthquake.usgs.gov/regional/world/events/1976_02_04.php Historic Earthquakes] {{webarchive. link. (2007-04-10)
2. "Significant Earthquake Information". National Geophysical Data Center / World Data Service (NGDC/WDS): NCEI/WDS Global Significant Earthquake Database. NOAA National Centers for Environmental Information..
3. Olcese (e.a.), 1977