Haiti can expect more aftershocks in coming weeks, and while the usual pattern suggests they will become weaker and less frequent, another one as strong as Wednesday's jolt is certainly possible, scientists say.
The battered nation has felt more than 45 significant aftershocks since the Jan. 12 quake. Wednesday's event, originally estimated at magnitude 6.1 but later revised to a 5.9, tied an earlier aftershock as the strongest so far.
These events are a sign the land is adjusting to "the new reality of the rock layers," said Bruce Pressgrave, a geophysicist with the U.S. Geological Survey.
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The extent of additional damage or injuries caused by the magnitude-5.9 temblor was not immediately clear. Prime Minister Jean-Max said the government was sending a plane and an overland team to check on the situation in Petit-Goave, the center of this morning's aftershock.
The U.S. Geological Survey said Wednesday's quake was centered about 35 miles west-southwest of Port-au-Prince and 6.2 miles below the surface — a little further from the capital than last week's epicenter was.
"It kind of felt like standing on a board on top of a ball," said U.S. Army Staff Sgt. Steven Payne. The 27-year-old from West Virginia was preparing to hand out food to refugees in a tent camp of 25,000 quake victims when the aftershock hit.
Eric Calais of Purdue University, who has studied earthquake potential in the region, said aftershocks could continue for several weeks and that another jolt as strong as Wednesday's would not be surprising.
"They will be less and less frequent, but large ones can still strike," he said. So buildings are still at risk, especially those already weakened, he said.
Julie Dutton, a USGS geophysicist, agreed that more aftershocks are probable and that another event like Wednesday's was certainly possible. "More likely we see that the earthquakes decrease in size, but you definitely have the potential that you can have a larger earthquake," she said.
Paul Mann of the University of Texas said it's hard to predict whether another sizable quake is in the future, since "we are dealing with a natural system that is very complex."
Calais also said the fault zone responsible for last week's quake extends into the neighboring nation, the Dominican Republic. It's "somewhat of a concern to us" that that the Haiti quake may have raised the chances for a quake there. The two countries share the island of Hispaniola.
But scientists don't know enough to make any forecasts, he said. "There is so much uncertainty," Calais said. "At this point we're working really hard to understand last week's earthquake, and from there we can perhaps understand what might happen next."
Mann said Haiti's disaster should not raise the risk of earthquakes throughout the wider Caribbean region. The area is seismically active anyway, he said, and people who feel a temblor shouldn't assume it's a reaction to last week's Haiti quake.
For people living well away from Haiti, such as in Trinidad, Venezuela, Colombia or Central America, "I don't think they should be fearful that the Haiti earthquake is going to activate a fault in their own back yard," Mann said.
The Associated Press contributed to this report.
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