Facts About Haiti’s Earthquakes

1. On August 14, 2021, at 8:29 a.m. local time, a magnitude 7.2 earthquake strikes southwestern Haiti at a depth of 6.2 miles (9.98km). According to USAID, the temblor left 2,248 deaths and 12,763 injuries. 1 It occurred as the result of oblique reverse motion along the Enriquillo-Plantain Garden fault zone (EPGFZ), about 125 km west of the Haitian capital Port-au-Prince. 2 It was at this same fault line, that the devastating earthquake of January 2010 also occurred, which left over 300 000 people dead. 3 The EPGFZ had produced a series of major earthquakes in both instrumentally and historical time periods. In addition to the two earthquakes mentioned above, it is likely the source of historical large earthquakes in 1860, 1770, and 1751, though none of these has been confirmed in the field as associated with this fault.

 

2. A brief history of catastrophic earthquakes in Haiti 4

– Nov. 21, 1751: A major earthquake destroys Port-au-Prince and causes major destruction in nearby towns.

– June 3, 1770: An earthquake hits Port-au-Prince again. Researchers described the event as one of the strongest shocks recorded on the island of Haiti. An estimated 200 people in the nation’s capital died because of the earthquake. The 2021 earthquake was reported to be near the site of the 1770 quake, which, at an estimated magnitude 7.5, is the largest known to ever strike within the EPGFZ.

– April 8, 1860: This earthquake occurred farther west of the 2010 earthquake, near Anse-à-Veau, and was accompanied by a tsunami.

 

3. Overall, the EPGFZ accommodates about 7mm per year of motion, nearly half of the total oblique convergence between the Caribbean and North America plates (~20mm per year). 2 Although this system had been free of any significant seismic activity for about two centuries, the strain that has been building up along the faults is now being released as huge bursts of energy, as Haiti has seen in 2010 and now once again. 4 It’s well established that the energy released by one earthquake alters the stress patterns elsewhere along the fault line. As the fault ruptures both vertically and laterally (see Figure 2.), it is hard to predict the exact location of the next earthquake.

 

4. The main factors that determine the severity of the outcome of an earthquake are the depth and location of the rupture, the time it occurred and the quality of construction. 3 Compared to the Earthquake that struck the coast of Tohoku, Japan, in February this year, the powerful magnitude 7.3 earthquake was estimated to be at a depth of about 55 kilometers, at least 100 injuries were reported, but none serious were confirmed. 7 The quake was believed by the official to be an aftershock from the Great East Japan Earthquake (M 9.0) that struck the same region on March 11, 2011. 7 Although the two earthquakes are similar in magnitude, the deeper depth of the Japanese earthquake and Japan’s dedication to structural stability led to minimizing casualties and structural damage.

 

5. The deadliness of the quakes in Haiti is the result of the structures on the surface as much as the shaking underground. 5 Many rural homes, churches, and schools were more affected than those in cities because many of them were built before 2010 when improved building codes were adopted nationwide after that year’s earthquake devastated Port-au-Prince. 9 Many structures in these rural regions use concrete, which is inexpensive and can be used to create heavy walls and roofs that resist hurricane winds. Since much of the concrete is unreinforced, it readily crumbles under the shaking of an earthquake. 5 Compounded by the inaccessibility of these rural regions and deteriorating security situation, it remains a challenge to get humanitarian aid to those who need it the most.

 

6. Since the August 14th earthquake, another 38 earthquakes of magnitude 3.8-5.8 have been recorded by the United States Geological Survey, occurring all around and along the EPGFZ. 2 About 600 aftershocks have been detected so far by Calais and colleagues, who are seismologists at the École Normale Supérieure in Paris. 11 Although the seismic risk remains high in the region, a different major geological region in Haiti’s north, knowns as the Septentrional fault zone, has also been getting many scientists’ attention. It unleashed a major quake in 1842, and many worry about the potential for producing another devastating earthquake.

 

References

1. USAID. (2021). Haiti – Earthquake Fact Sheet #13, Fiscal Year (FY) 2021. Retrieved September 20, 2021, from https://reliefweb.int/report/haiti/haiti-earthquake-fact-sheet-13-fiscal-year-fy-2021
2. United States Geological Survey. (2021). M 7.2 – Nippes, Haiti. Retrieved September 20, 2021, from https://earthquake.usgs.gov/earthquakes/eventpage/us6000f65h/executive
3. The New York Times. (2021). The latest Haiti earthquake was more powerful than the devastating quake in 2010. Retrieved September 20, 2021, from https://www.nytimes.com/2021/08/14/world/americas/haiti-earthquake-2021-2010.html
4. NPR. (2021). Why Earthquakes In Haiti Are So Catastrophic. Retrieved September 20, 2021, from https://www.npr.org/2021/08/16/1027990749/haiti-earthquake-why-deadly-explainer
5. National Geography. (2021). Here’s what makes earthquakes so devastating in Haiti. Retrieved September 21, 2021, from https://www.nationalgeographic.com/science/article/heres-what-makes-earthquakes-so-devastating-in-haiti
6. ArcGIS StoryMaps. (2020). The Clashing Dinner Plates- Haiti, 2010. Retrieved September 20, 2021, from https://storymaps.arcgis.com/stories/cd854d7d98e24838bccad8636bff633f
7. The Japan Times. (2021). Powerful magnitude 7.3 earthquake jolts Tohoku area. Retrieved September 21. 2021, from https://www.japantimes.co.jp/news/2021/02/14/national/earthquake-fukushima/
8. Cushman & Wakefield. (2017). Learning from the best: How the Japanese earthquake-proof their buildings. Retrieved September 21, 2021, from https://www.cushmanwakefield.com/en/singapore/insights/blog/learning-from-the-best-how-the-japanese-earthquake-proof-their-buildings
9. The Guardian. (2021). ‘A forgotten disaster’: earthquake-hit Haitians left to fend for themselves. Retrieved September 21, 2021, from https://www.theguardian.com/global-development/2021/sep/17/a-forgotten-disaster-earthquake-hit-haitians-left-to-fend-for-themselves
10. International Medical Corps. (2021). 2021 Haiti EARTHQUAKE Situation Report #3 – September 21, 2021. Retrieved September 21, 2021, https://reliefweb.int/report/haiti/2021-haiti-earthquake-situation-report-3-september-20-2021
11. Nature. (2021). Home seismometers provide crucial data on Haiti’s quake. Retrieved September 22, 2021, https://www.nature.com/articles/d41586-021-02279-y
12. NPR. (2010). The Anatomy Of A Caribbean Earthquake. Retrieved September 22, 2021, https://www.npr.org/templates/story/story.php?storyId=122531261

Written by Jennifer ShuPing Chen