Rapid response science missions assess potential for another major Haiti earthquake

Map of area of January 12 earthquake and aftershocks.  The colors show calculated differences from before and after the earthquake in radar images.  The close bands of color indicate greater deformation. Notice how a set of  colored rings are centered over the offshore region near where the tsunami also occurred.
Map of area of January 12 earthquake and aftershocks. The colors show calculated differences from before and after the earthquake in radar images. The close bands of color indicate greater deformation. Notice how a set of colored rings are centered over the offshore region near where the tsunami also occurred.

To help assess the potential threat of more large earthquakes in Haiti and nearby areas, scientists at The University of Texas at Austin’s Institute for Geophysics are co-leading three expeditions to the country with colleagues from Purdue University, Lamont-Doherty Earth Observatory, the U.S. Geological Survey and five other institutions.

Rapid response missions can be critical for assessing future risks because a fault can continue to displace the ground for weeks and months after a large earthquake. At the same time, natural weathering processes and human activities can erase valuable geologic evidence.

The goal of the Haiti missions, researchers say, is to understand which segments of the earthquake fault ruptured during the Jan. 12 quake and how much fault movement and uplift of coastal features occurred in locations along or near the fault.

  • Expedition 1: Eric Calais of Purdue University led the first expedition, which has ended, collecting Global Positioning System (GPS) data to determine how land moved as a result of the earthquake. A second team participating in the expedition, led by Paul Mann of the Institute for Geophysics and Rich Koehler of the Alaska Division of Geological & Geophysical Surveys, used a helicopter and fieldwork to search for signs of ruptures-cracks at the surface along the main trace of the suspected earthquake fault. They found no signs of surface rupture but evidence for lateral spreading and liquefaction-a phenomenon in which soils behave like a liquid instead of a solid. Earthquakes most likely caused by the same fault and resulting in the same kind of lateral spreading and liquefaction destroyed the Jamaican capital of Kingston in 1692 and 1907. Funding was provided by the Rapid Response Research Program of the National Science Foundation (NSF).

  • Expedition 2: The second expedition, beginning Feb. 24, will for the first time use a scientific research vessel to examine the underwater effects of the quake. Chief scientist for the expedition is Cecilia McHugh at the City University of New York and Lamont-Doherty Earth Observatory with co-chief scientists Sean Gulick of the Institute for Geophysics and Milene Cormier of the University of Missouri. For two weeks, a team onboard the RV Endeavor will use sonar to map shifted sediments on the seafloor and seismic sensors to examine faults beneath the seafloor. The scientists hope to solve a mystery about how the earthquake unleashed a tsunami that killed seven people and to explain why corals along the coast have now been uplifted above sea level. The 185-foot Endeavor is owned by the NSF and operated by the University of Rhode Island. Funding is provided by the NSF and The University of Texas at Austin’s Jackson School of Geosciences.

  • Expedition 3: The third expedition, led by Fred Taylor of the Institute for Geophysics, will focus on large coral heads exposed by coastal uplift during the earthquake. Taylor will use a specialized chainsaw to collect the now dead coral for study of its tree ring-like structure to reveal clues on recent uplift and previous uplifts extending back hundreds of years. He will be assisted by Mann along with Rich Briggs and Carol Prentice of the U.S. Geological Survey (USGS). The Jackson School of Geosciences and USGS are jointly funding the coral study.

The Jackson School places a special emphasis on mounting rapid response missions to the scenes of geo-hazards, supporting previous missions after the earthquake and tsunami in the Solomon Islands (2007) and Hurricane Ike along the Texas Gulf Coast (2008). Few academic organizations have the infrastructure, equipment and expertise to mount a large field expedition on a few weeks’ notice, yet they can yield valuable insights to prepare communities for future hazards.

“We expect a whole raft of studies about the Haiti earthquake coming out based on remote sensing data from satellites and airplanes,” said Sean Gulick of the Institute for Geophysics. “But there’s no substitute for getting on the ground and in the water to look directly at its immediate effects.”

While collecting information that can save lives in the near future is a top priority of the expeditions, the scientists are also working to help cultivate local earthquake expertise. Two Haitian scientists have been invited to participate-Nicole Dieudonne, a representative of the Haitian Bureau of Mines and Energy, and Steeven Smyithe, a student from the State University of Haiti.

“We’re trying to engage the Haitian science community,” said Mann, who will return to Haiti for the second expedition. “They can help us communicate better with Haitian policy makers and people about the geology behind this devastating earthquake and about the risks going forward.”

In 2008, Mann, Calais and colleagues presented a paper at the Caribbean Conference forecasting a 7.2 magnitude earthquake in the area of Haiti, Jamaica and the Dominican Republic. The forecast was based on an integration of geologic information on the Enriquillo-Plantain Garden fault zone with GPS data collected in the region. David Manaker, Calais and colleagues published an article on the same topic in Geophysical Journal International.

New satellite maps of Haiti coming in

This is a damage evaluation map based on satellite data over the Port-au-Prince area of Haiti, following a 7.0 magnitude earthquake and several aftershocks that hit the Caribbean nation on 12 January. Map based on data from CNES's SPOT-5, JAXA's ALOS and the US-based GeoEye-1 satellites; this was processed by SERTIT. -  CNES, JAXA, GeoEye, SERTIT
This is a damage evaluation map based on satellite data over the Port-au-Prince area of Haiti, following a 7.0 magnitude earthquake and several aftershocks that hit the Caribbean nation on 12 January. Map based on data from CNES’s SPOT-5, JAXA’s ALOS and the US-based GeoEye-1 satellites; this was processed by SERTIT. – CNES, JAXA, GeoEye, SERTIT

As rescue workers scramble to provide assistance to hundreds of thousands of people following Haiti’s earthquake, Earth observation satellite data continues to provide updated views of the situation on the ground.

Following the 7.0-magnitude earthquake that hit Haiti on 12 January, international agencies requested satellite data of the area from the International Charter on ‘Space and Major Disasters’.

The Charter, an international initiative aimed at providing satellite data free of charge to those affected by disasters anywhere in the world, immediately began re-tasking their satellites to get the data urgently needed.

Data are being collected by various satellites including Japan’s ALOS, CNES’s Spot-5, the U.S.’s WorldView and QuickBird, Canada’s RADARSAT-2, China’s HJ-1-A/B and ESA’s ERS-2 and Envisat.

These data are being processed into maps that show the degree of destruction. As soon as new data arrives, updated maps will be produced and made available to the international community.

Haiti quake occurred in complex, active seismic region




The Haiti earthquake epicenter is marked by the star along the displaced portion (shown in red) of the Enriquillo-Plantain Garden Fault. The 7.0 magnitude quake struck along about one-tenth of the 500-km-long strike-slip fault. The region sits on a complex  seismic area made up of numerous faults and plates. The fault lines with small arrows denote a different kind of fault called thrust faults, where one plate dives under another. Strike-slip faults grind past one another. The dotted lines at bottom denote complex seafloor formations. (Source: Jansma, P. and Mattioli, G., 2005, GPS results from Puerto Rico and the Virgin Islands: constraints on tectonic setting and rates of active faulting, Geol. Soc. Amer. Spec. Paper 385 (ed. Paul Mann), 13-30.)
The Haiti earthquake epicenter is marked by the star along the displaced portion (shown in red) of the Enriquillo-Plantain Garden Fault. The 7.0 magnitude quake struck along about one-tenth of the 500-km-long strike-slip fault. The region sits on a complex seismic area made up of numerous faults and plates. The fault lines with small arrows denote a different kind of fault called thrust faults, where one plate dives under another. Strike-slip faults grind past one another. The dotted lines at bottom denote complex seafloor formations. (Source: Jansma, P. and Mattioli, G., 2005, GPS results from Puerto Rico and the Virgin Islands: constraints on tectonic setting and rates of active faulting, Geol. Soc. Amer. Spec. Paper 385 (ed. Paul Mann), 13-30.)

The magnitude 7.0 earthquake that triggered disastrous destruction and mounting death tolls in Haiti this week occurred in a highly complex tangle of tectonic faults near the intersection of the Caribbean and North American crustal plates, according to a quake expert at the Woods Hole Oceanographic Institution (WHOI) who has studied faults in the region and throughout the world.

Jian Lin, a WHOI senior scientist in geology and geophysics, said that even though the quake was “large but not huge,” there were three factors that made it particularly devastating: First, it was centered just 10 miles southwest of the capital city, Port au Prince; second, the quake was shallow-only about 10-15 kilometers below the land’s surface; third, and more importantly, many homes and buildings in the economically poor country were not built to withstand such a force and collapsed or crumbled.

All of these circumstances made the Jan. 12 earthquake a “worst-case scenario,” Lin said. Preliminary estimates of the death toll ranged from thousands to hundreds of thousands. “It should be a wake-up call for the entire Caribbean,” Lin said.

The quake struck on a 50-60-km stretch of the more than 500-km-long Enriquillo-Plantain Garden Fault, which runs generally east-west through Haiti, to the Dominican Republic to the east and Jamaica to the west.

It is a “strike-slip” fault, according to the U.S. Geological Survey, meaning the plates on either side of the fault line were sliding in opposite directions. In this case, the Caribbean Plate south of the fault line was sliding east and the smaller Gonvave Platelet north of the fault was sliding west.

But most of the time, the earth’s plates do not slide smoothly past one another. They stick in one spot for perhaps years or hundreds of years, until enough pressure builds along the fault and the landmasses suddenly jerk forward to relieve the pressure, releasing massive amounts of energy throughout the surrounding area. A similar, more familiar, scenario exists along California’s San Andreas Fault.

Such seismic areas “accumulate stresses all the time,” says Lin, who has extensively studied a nearby, major fault , the Septentrional Fault, which runs east-west at the northern side of the Hispaniola island that makes up Haiti and Dominican Republic. In 1946, an 8.1 magnitude quake, more than 30 times more powerful than this week’s quake, struck near the northeastern corner of the Hispaniola.

Compounding the problem, he says, is that in addition to the Caribbean and North American plates, , a wide zone between the two plates is made up of a patchwork of smaller “block” plates, or “platelets”-such as the Gonvave Platelet-that make it difficult to assess the forces in the region and how they interact with one another. “If you live in adjacent areas, such as the Dominican Republic, Jamaica and Puerto Rico, you are surrounded by faults.”

Residents of such areas, Lin says, should focus on ways to save their lives and the lives of their families in the event of an earthquake. “The answer lies in basic earthquake education,” he says.

Those who can afford it should strengthen the construction and stability of their houses and buildings, he says. But in a place like Haiti, where even the Presidential Palace suffered severe damage, there may be more realistic solutions.

Some residents of earthquake zones know that after the quake’s faster, but smaller, primary, or “p” wave hits, there is usually a few-second-to-one-minute wait until a larger, more powerful surface, or “s” wave strikes, Lin says. P waves come first but have smaller amplitudes and are less destructive; S waves, though slower, are larger in amplitude and, hence, more destructive.

“At least make sure you build a strong table somewhere in your house and school,” said Lin. When a quake comes, “duck quickly under that table.”

Lin said the Haiti quake did not trigger an extreme ocean wave such as a tsunami, partly because it was large but not huge and was centered under land rather than the sea.

The geologist says that aftershocks, some of them significant, can be expected in the coming days, weeks, months, years, “even tens of years.” But now that the stress has been relieved along that 50-60-km portion of the Enriquillo-Plantain Garden Fault, Lin says this particular fault patch should not experience another quake of equal or greater magnitude for perhaps 100 years.

However, the other nine-tenths of that fault and the myriad networks of faults throughout the Caribbean are, definitely, “active.”

“A lot of people,” Lin says, “forget [earthquakes] quickly and do not take the words of geologists seriously. But if your house is close to an active fault, it is best that you do not forget where you live.”