Haiti dealt another destructive blow by Mother Nature

Satellite image from USGS.

By UM News

Satellite image from USGS.

Haiti dealt another destructive blow by Mother Nature

By UM News
UM marine geoscientist answers questions about the 5.9-magnitude quake that stuck the island nation Saturday.

Still reeling from a 2010 earthquake that killed hundreds of thousands of people and destroyed its capital city, Haiti was dealt another destructive blow on Saturday when a 5.9-magnitue temblor struck the northern portion of the island nation, killing at least 12 and injuring more than 180. 

And making matters worse, a 5.2-magnitude aftershock hit the island on Sunday, even as survivors were attempting to recover from the previous day’s quake.

Saturday’s earthquake, which hit near the port city of Port-de-Paix, where most of the deaths were concentrated, is one of the latest in a series of natural disasters that have devastated Haiti. Two years ago Hurricane Matthew battered southwestern Haiti, leaving widespread damage in the poorest country in the Western Hemisphere. 

Falk Amelung, professor in the Department of Marine Geosciences at the University of Miami’s Rosenstiel School of Marine and Atmospheric Science, explains the nature of plate tectonics indicative of the area where Haiti is located and why the country is so vulnerable to seismic activity: 

Why does it is seem Haiti gets hit with powerful and deadly earthquakes on a regular basis? 

Haiti, which shares the island of Hispaniola with the Dominican Republic, is located in the boundary zone between the North American and Caribbean tectonic plates. The Caribbean moves at a rate of 2 centimeters a year with respect to North America. So there is a total of 2 meters of plate displacement every 100 years that somehow has to be accommodated in earthquakes.

This quake hit the northern area of the country. That seems a remote spot. Is there anything significant about the location?

Tectonics in this area is mostly strike-slip (horizontal movements), with a component of contraction. There are two major strike-slip fault systems on Hispaniola: the Enriquillo Plantain Garden Fault zone in the south, along which the 2010 earthquake occurred, and the Septentrional-Oriente Fault in the north. The latter passes through northern Dominican Republic, offshore north of Haiti, and offshore south of eastern Cuba. The crustal contraction is accommodated by very slow subduction of the North American Plate under the Caribbean further north and crustal thrust or oblique faulting. The earthquake occurred on or near the offshore section of the Septentrional-Oriente fault. According to seismic data, it was a crustal thrust earthquake. This is a mystery, as we would expect a strike-slip or oblique-slip earthquake in this area.

Given the location of the epicenter, did Cuba also experience damage from this earthquake? 

I don’t think so. At 150 kilometers distance, it is unlikely that Cuba sustained any damage from an earthquake of this size, but people must have felt it.

The aftershock of the quake registered at 5.2, almost as powerful as the initial 5.9-magnitude quake. Is that common, or is it indicative of this area? 

Nothing unusual. But what has to be considered is that there is always a possibility that an earthquake is a foreshock to something bigger. The probability for a larger earthquake in the first three days after the quake is 6 percent. After a few days the probability for a larger quake to occur goes down.

With earthquakes in the Caribbean Basin, is there any possibility of tsunamis forming that would threaten other areas? 

The vertical motion associated with the earthquake was not enough to generate a tsunami. Given the dominant strike-slip tectonics it is unlikely that crustal earthquakes in this area generate large regional tsunamis. However, the subduction megathrust fault, although it is relatively small compared to the circum-pacific subduction zones, has the potential of generating a tsunami. Furthermore, as we have seen in Sulawesi, there is always the possibility of ground shaking-induced submarine landslides.