1912 Acambay earthquake explained

1912 Acambay earthquake
Local-Time:07:55
Timestamp:1912-11-19 13:55:03
Isc-Event:16958218
Anss-Url:iscgem16958218
Local-Date:19 November 1912
Magnitude:6.7
Type:Normal
Affected:Mexico
Aftershocks:60
Casualties:140–1,200 killed
Countries Affected:Mexico

The 1912 Acambay earthquake affected central Mexico on 19 November at 07:55 local time. It had a moment magnitude of 6.7 and an epicenter in the Acambay graben, northwest of Mexico City. Damage was severe in Acambay and several nearby villages, and the casualty toll ranged between 140 and 1,200. There was also significant damage in Mexico City and one fatality. The earthquake occurred along three fault zones that bound the Acambay graben, an extensional tectonic feature located within the Trans-Mexican Volcanic Belt. Surface ruptures were observed on these fault zones.

Tectonic setting

The Trans-Mexican Volcanic Belt (TMVB) which spans across central Mexico, from near the Pacific coast to the Gulf of Mexico, for more than . It is the product of ongoing volcanism related to subduction of the Cocos and Rivera plates beneath the North American plate. As a result, volcanoes erupt through the North American plate. Within the TMVB, active extensional tectonics is ongoing, particularly prominent west of the 100°W latitude. The cause of this extension may be caused by the North American plate reaching a state of isostatic equilibrium because of the large load exerted by the TMVB.[1] Within the central part of the TMVB, east–west trending normal faults can produce earthquakes. Some of these faults form escarpments visible for . The overlying Holocene alluvium and Quaternary cinder cones have shown displacements caused by these faults.[2]

Earthquake

The earthquake, with a magnitude of 6.7, occurred within the Acambay graben in the central region of the TMVB. It had an epicenter near the graben's southern margin. This graben, located northwest of Mexico City,[3] measures long and across. A maximum Modified Mercalli intensity of XI (Extreme) was observed at several locations within the graben. The graben features three faults; the Acambay–Tixmadejé and Pastores faults which forms its northern and southern boundary, and a central fault inside the structure. The Acambay–Tixmadejé Fault is a, normal fault that dips at 60–70° southwards while the Pastores Fault extends and features tall scarps. The intragraben fault zone stretches across the Temascalcingo volcano featuring multiple strands that rupture through the volcano.[4]

Surface ruptures were observed along all three fault zones. The Acambay-Tixmadejé Fault produced a surface rupture, starting west at San José Solís, passing north of Acambay, and terminating near the Huapango reservoir. The largest vertical displacement of occurred near Tixmadejé village, about midway along the rupture between Acambay and San José Solís. East of the reservoir, a northwest–southeast trending rupture, likely an extension of the Acambay–Tixmadejé Fault, stretched with vertical displacements of . On the Pastores Fault, a rupture trending east–west occurred between Santiago Coachochitlán and Mayé el Fresno. Within the graben, three parallel ruptures were recorded near Temascalcingo, corresponding to the intragraben fault zone, with the longest extending .[5] Sixty aftershocks were recorded between 19 November 1912 and 15 April 1913.

Impact

The number of casualties varied across newspaper reports. According to the Mexican government, citing El Imparcial on 21 November, at least 140 people died.[6] Citing the Mexican interior secretariat, Meriden Daily Journal reported on 22 November that over 1,200 people were killed.[7] An additional nine deaths was reported in Temaxculcingo, three in Atlacomulco and one in Eloro.[8] Many of the dead were never recovered from the rubble and their decomposing bodies attracted pests.[9] An unspecified number of people died the following year from starvation.[10] The town of Acambay was levelled as few buildings remained undamaged. Several surrounding villages were also destroyed.[11] Over 100 church worshippers died when the building collapsed onto the crowd.[12] Wells, springs and streams dried up following the earthquake so some survivors resorted to ponds for water. Their frequent reliance made these ponds a breeding ground for contagious and deadly viruses. Rebels from outside the area looted the affected communities and attacked its residents.[13] In response to these rebel presence, the Mexican government said they would deploy soldiers to defend the area and allow outside assistance to enter. In parts of Mexico City, the earthquake knocked out gas and water services.[14] Cracks appeared in the walls of the National Palace while some poorly-constructed homes collapsed. On the streets, water pipes ruptured and roads buckled.[15] One person died and many others were injured in the city.[16]

See also

Notes and References

  1. Ferrari . Luca . Orozco-Esquivel . Teresa . Manea . Vlad . Manea . Marina . The dynamic history of the Trans-Mexican Volcanic Belt and the Mexico subduction zone . Tectonophysics . 2012 . 522–523 . 122–149 . 10.1016/j.tecto.2011.09.018.
  2. Gerardo . Suárez . Gema V. . Caballero‐Jiménez . David A. . Novelo‐Casanova. 30 August 2019. Active Crustal Deformation in the Trans‐Mexican Volcanic Belt as Evidenced by Historical Earthquakes During the Last 450 Years. Tectonics. 38. 10. 3544–3562. 10.1029/2019TC005601. 2019Tecto..38.3544S . 202923598 . John Wiley & Sons. free.
  3. 1996. Bulletin of the Seismological Society of America. Macroseismic Study of Shallow Earthquakes in the Central and Eastern Parts of the Trans-Mexican Volcanic Belt, Mexico. 10.1785/BSSA0860061952. 86. 6. 1952–1963. M.. Suter. M.. Carrillo-Martfnez. O.. Quintero-Legorreta. 1996BuSSA..86.1952S. 132743263.
  4. Langridge . Robert Max . Weldon II . Ray J. . Moya . Juan Carlos . Suárez . Gerardo . Paleoseismology of the 1912 Acambay earthquake and the Acambay‐Tixmadejé fault, Trans‐Mexican Volcanic Belt . Journal of Geophysical Research: Solid Earth . 2000 . 105 . B2 . 3019-3037 . 10.1029/1999JB900239.
  5. Suter . Max . Quintero-Legorreta . Odranoel . López-Martinez . Margarita . Aguirre-Díaz . Gerardo . Farrar . Edward . The Acambay graben: Active intraarc extension in the trans-Mexican volcanic belt, Mexico . Tectonics . 1995 . 14 . 6 . 1245–1262 . 10.1029/95TC01930.
  6. Web site: A 108 años del sismo de Acambay. 108 years after the Acambay earthquake. es . . 4 December 2024 . 19 November 2020.
  7. News: 1,200 were killed by earthquake . 4 December 2024 . The Meriden Daily Journal . 22 November 1912 . 7.
  8. News: Whole Mexican town destroyed by earthquake . 4 December 2024 . . 22 November 1912 . 7. 3247.
  9. News: Thousands dead in earthquake . 4 December 2024 . Warsaw Daily Times . 30 November 1912 . 3.
  10. News: Earthquake victims starving . 4 December 2024 . Warsaw Daily Times . 1 January 1913 . 4.
  11. News: 1,200 may have lost lives in Mexican quake . 4 December 2024 . . 22 November 1912. 17. 1. 6.
  12. News: 1000 died in Mexico earthquake . 4 December 2024 . . . 22 November 1912.
  13. News: Thousands die in earthquake . 4 December 2024 . Greensburg Daily Tribune . 30 November 1912 . 3.
  14. News: One hundred dead by earthquake . 42. 19. 4 December 2024 . The Evening News . 21 November 1912.
  15. News: Severe earthquake. 279. 142 . 16 . 4 December 2024 . . 20 November 1912.
  16. News: Earthquake in Mexico . 4 December 2024 . . 21 November 1912 . 9.