PORT-AU-PRINCE, Haiti — An aftershock that measured 5.9 rolled through parts of Haiti early Wednesday morning, rattling buildings and scaring Haitians still reeling from last week's 7.0-magnitude quake.
A second, compounding concern in a possible one-two punch Wednesday is the threat of rain in and around Port-au-Prince.
Locals say that while it doesn't rain much in Haiti during this season, when it does, it pours. Extensive rains could wash out or expose more corpses, send unwanted torrents of water into damaged areas and hamper ongoing relief and recovery efforts.
Wednesday's quake was the largest aftershock yet in the wake of the Jan. 12 earthquake that killed an estimated 200,000 people in Haiti, left 250,000 injured and made 1.5 million homeless, according to the European Union Commission.
The extent of additional damage or injuries was not immediately clear.
The U.S. Geological Survey said the quake was centered about 35 miles (60 kilometers) northwest of Port-au-Prince and 6.2 miles (9.9 kilometers) below the surface.
The Associated Press reported wails of terror in the capital city as clouds of dust rose from the aftershock.
The medical team of volunteer doctors and nurses sponsored in Haiti by The Church of Jesus Christ of Latter-day Saints was housed Tuesday night at a multibuilding compound some 20 miles north of the capital city. It is owned by a friend of the LDS Church who does extensive contracting and construction work for the church in Haiti.
The aftershock hit shortly after 6 a.m. Haiti time (4 a.m. Mountain) and lasted about 15 to 20 seconds. Haitian workers staying throughout the compound — all veterans of last week's quake — scrambled to gather in a wide-open area, well away from buildings and trees.
The battered nation has felt more than 40 aftershocks since the Jan. 12 quake, with Wednesday's temblor the strongest.
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.
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. "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.
While Wednesday's tremors didn't cause any damage at the compound where the LDS relief team is staying, it did result in the waters of a large swimming pool sloshing over the pool edges like a mini-tsunami.
Medical team members scattered throughout the compound to sleep Tuesday night after a long day of work and a fitful overnight bus ride into Haiti that began late Monday night from the Dominican Republic. Some slept in the main house, some on mattresses in a small guest house and others in tents from survival bags given each team member.
Some team members were so exhausted they slept through Wednesday's aftershock.
David Sindel, a critical-care nurse from Provo, slept on a mattress out in a large patio-like covered area with all the bags of pharmaceuticals, medical supplies and survival bags. Immediately after the aftershocks hit Wednesday morning, he and another member of the team hurried to move clinical supplies outside in case any subsequent follow-up quakes might level the patio area and bury critical supplies under concrete columns and a heavy metal roof.
Elsewhere, at the central University Hospital facility, Dr. Evan Lyon of the U.S.-based Partners in Health, messaged that the facility was within 24 hours of running out of key operating room supplies. Troops of the 82nd Airborne Division were providing security at the hospital. A helicopter landing pad was designated nearby for airlifting the most critical patients to the U.S. Navy hospital ship Comfort.
The great white ship, 894 feet (272 meters) long, with a medical staff of 550, was anchored in Port-au-Prince harbor and had taken aboard its first two surgical patients by helicopter late Tuesday even as it was steaming in.
It joined the aircraft carrier Carl Vinson and other U.S. warships offshore, along with the French landing craft Francis Garnier, which carried a medical team, hundreds of tents and other aid.
The Garnier offloaded pallets of bottled water and prepared meals at the city's quake-damaged port, while U.S. Army divers surveyed the soundness of the main pier, where trucks drove only on the edges because of damage down its center.
The seaborne rescue fleet will soon be reinforced by the Spanish ship Castilla, with 50 doctors and 450 troops, and by three other U.S.-based Navy vessels diverted from a scheduled Middle East mission. Canadian warships were already in Haitian waters, and an Italian aircraft carrier, the Cavour, also will join the flotilla with medical teams and engineers.
U.N. humanitarian chief John Holmes said at U.N. headquarters in New York that it's believed that 3 million people are affected, with 2 million of those needing food for at least six months.
Between the U.N. World Food Program and deliveries by the Red Cross and other private aid groups, about a half-million Haitians should have been reached with "reasonable quantities of food," he said. "That's still very far short of what's needed."
At the hillside tent camp, set up on a golf course where an 82nd Airborne unit has its base, the lines of hungry and thirsty stretched downhill and out of sight as paratroopers handed out bottled water and ready-to-eat meals as fast as helicopters brought them in.
Contributing: Paul Haven, Mike Melia, Malcolm Ritter, Associated Press