Scientists anxious about other big quakes

Published 19 January 2010

The Haitian earthquake may have increased the chance of a future quake in the neighboring Dominican Republic and other parts of the Caribbean; during the Haitian quake, only 30 to 60 miles of the 300-mile fault near Port-au-Prince ruptured and slid; the rest of it stayed stuck, still glued together by friction; the area that ruptured is likely to have increased the amount of strain — and the risk of quake — in other parts of the fault

Strike-slip fault // Source:

In the last several days, while the attention of the world has been focused on the human toll of Tuesday’s earthquake in Haiti, scientists have begun to look at the quake’s geological toll. What is the danger to populations living along other fault lines in the Caribbean, they are asking, and what other parts of the world are at risk?

ISNS reports that seismologists have just started the long process of analyzing the geological reverberations of the magnitude 7.0 quake. They are worried that this week’s natural disaster could increase the chance of another temblor in Haiti, though their computer models may ease their minds after all of the data has been crunched. “We’re most concerned about the Haitian peninsula, the area west of this fault rupture” said seismologist Carol Prentice of the U.S. Geological Survey (USGS) in Menlo Park, California, who studies the Caribbean.

Pending a more detailed analysis — which will take weeks and may be hampered by the lack of data-collecting equipment in Haiti — Prentice said that the Haitian earthquake may have increased the chance of a future quake in the neighboring Dominican Republic as well. She added that the likelihood of the event having repercussions for other Caribbean nations such as Jamaica, Cuba and Puerto Rico is extremely low, however. “Jamaica, Cuba, the whole area needs to worry about earthquakes for other reasons,” said Prentice. “But this particular earthquake is unlikely to change the stress in faults that far away.”


A history of violence

Worldwide, earthquakes of magnitude 7.0 and larger are reported about eighteen times each year, and at least a dozen of them occurred in the Caribbean over the last 500 years. In 1946 a magnitude 7.6 earthquake in the Dominican Republic left 20,000 homeless, and the 1843 earthquake in the Leeward Islands killed an estimated 5,000.

Connected to each other beneath the ocean, these island nations all sit on one large piece of the Earth’s crust called the Caribbean Plate. This tectonic plate is slowly sliding eastwards relative to the neighboring North American plate. But the edges of the two plates do not glide past each other smoothly. Instead, they lock up and a stick together, forming cracks or “faults” in which strain builds up. When the strain becomes too great, the rocks on either side of the fault slip past each other suddenly and, in extreme cases, produce a large earthquake. Two of these “strike-slip” faults