Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Purdue-led research team finds Haiti quake caused by unknown fault

26.10.2010
Researchers found a previously unmapped fault was responsible for the devastating Jan. 12 earthquake in Haiti and that the originally blamed fault remains ready to produce a large earthquake.

Eric Calais, a Purdue University professor of earth and atmospheric sciences, led the team that was the first on the ground in Haiti after the magnitude 7.0 earthquake, which killed more than 200,000 people and left 1.5 million homeless.

The team determined the earthquake's origin is a previously unmapped fault, which they named the Léogâne fault. The newly discovered fault runs almost parallel to the Enriquillo fault, which was originally thought to be the source of the earthquake, he said.

"This means that the Enriquillo fault is still capable of producing large earthquakes and that Haiti has to adapt to this seismic hazard," said Calais, who in September was appointed science adviser for the United Nations Development Program in Haiti. "The fault system is more complex than we originally thought, and we don't yet know how the January earthquake impacted the other faults. Preliminary measurements indicate that the Enriquillo fault did not release any accumulated seismic energy and, therefore, remains a significant threat for Haiti, and Port-au-Prince in particular. We need to investigate the fault system further to be able to determine where the next earthquakes might occur and how large they could be."

The shifting of the Earth's crust after a major earthquake can add to or reduce stresses building up in nearby faults and can apply pressures that effectively stop or release other earthquakes. Because of this, the earthquake along the Léogâne fault may have delayed or advanced the timing for the next earthquake on the Enriquillo fault, he said.

"For practical purposes, speculating on when the next earthquake might happen is not an effective strategy," Calais said. "We rather need to focus attention, energy and funds on proactive measures to help the country adapt to earthquake hazards and, eventually, reduce economic losses and save lives. Our finding raises many important scientific questions and we are working to find the answers, but we already know that the earthquake threat in Haiti is inexorable. The reconstruction process that is now starting in Haiti is an opportunity to build better, of course, but also to develop an effective prevention and mitigation strategy for the future."

The team analyzed data they recorded before the Jan. 12 earthquake and new measurements taken after the event. Their work is detailed in a paper that will be published in the November issue of Nature Geosciences.

Andrew Freed, paper co-author and a Purdue professor of earth and atmospheric sciences, said the absence of any surface rupture was the first clue that the earthquake did not happen along the Enriquillo fault.

"It was a big surprise that we couldn't find a surface rupture anywhere," Freed said. "We did find other physical changes that we expected after an earthquake of that magnitude, but in entirely the wrong location to have come from the Enriquillo fault."

For instance the team found that the epicenter area rose by a little more than half a meter and that the earthquake caused contraction of the Earth's crust opposite of what would be expected from the Enriquillo fault, he said.

The team used global positioning system equipment and radar interferometry to measure how the ground moved during the earthquake, which provides insight into what is happening as much as 20 kilometers below the surface. The team then used a computer model to determine what characteristics the source of the earthquake must have in order to produce the observed changes.

Through this work, the team discovered the previously unmapped Léogâne fault, which is located just to the north of the Enriquillo fault and dips by a 60-degree angle to the north. The fault is a blind thrust, meaning one side of the fault is being thrust over the other, but the fault does not reach the surface.

About 30 kilometers of the fault shifted during the January earthquake, and the sides of the fault moved by as much as five meters relative to each other below the Earth's surface. The full length of the fault is not known, Freed said.

"Only portions of a fault are affected during any given earthquake, and the length of the portion affected is relative to the magnitude of the event," Freed said. "Because this is a blind fault, we don't have some of the clues at the surface, like scars from past ruptures, that show where the fault runs. On the Enriquillo fault you can almost walk the line of the fault because scars from many past events reveal the fault below. That isn't the case with the Léogâne fault."

The team plans to continue to take measurements of the postseismic processes that allow them to understand changing stresses within the Earth's crust over time that could help point to areas where seismic hazard is increasing. In addition they plan to create models to better understand the fault systems, their behavior and why they exist at these particular locations, Freed said.

In addition to Freed, co-authors include Glen Mattioli of the University of Arkansas; Falk Amelung, Sang-Hoon Hong and Timothy Dixon of the University of Miami; Sigurjón Jónsson of the King Abdullah University of Science and Technology in Saudi Arabia; Pamela Jansma of the University of Texas at Arlington; Claude Prépetit of the Bureau of Mines in Haiti; and Roberte Momplaisir of the State University of Haiti.

Calais has studied the Enriquillo and Septentrional faults on the island of Hispaniola, which includes Haiti and the Dominican Republic, since 1989. His research team has been measuring the build up of energy along these faults using global positioning system technology for 10 years. The team first reported the risk for a major earthquake there in 2008.

This work was funded by the National Science Foundation and the National Disaster Risk Management System Development Program of the United Nations Development Program in Haiti. It was performed in collaboration with, and in support to, the Haitian National System for Disaster Risk Reduction.

Writer: Elizabeth K. Gardner, 765-494-2081, ekgardner@purdue.edu
Sources: Eric Calais, ecalais@purdue.edu
Andrew Freed, freed@purdue.edu

Elizabeth K. Gardner | EurekAlert!
Further information:
http://www.purdue.edu

More articles from Earth Sciences:

nachricht AWI researchers measure a record concentration of microplastic in arctic sea ice
24.04.2018 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung

nachricht Climate change in a warmer-than-modern world: New findings of Kiel Researchers
24.04.2018 | Christian-Albrechts-Universität zu Kiel

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Why we need erasable MRI scans

New technology could allow an MRI contrast agent to 'blink off,' helping doctors diagnose disease

Magnetic resonance imaging, or MRI, is a widely used medical tool for taking pictures of the insides of our body. One way to make MRI scans easier to read is...

Im Focus: BAM@Hannover Messe: innovative 3D printing method for space flight

At the Hannover Messe 2018, the Bundesanstalt für Materialforschung und-prüfung (BAM) will show how, in the future, astronauts could produce their own tools or spare parts in zero gravity using 3D printing. This will reduce, weight and transport costs for space missions. Visitors can experience the innovative additive manufacturing process live at the fair.

Powder-based additive manufacturing in zero gravity is the name of the project in which a component is produced by applying metallic powder layers and then...

Im Focus: Molecules Brilliantly Illuminated

Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.

Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...

Im Focus: Spider silk key to new bone-fixing composite

University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.

Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

World's smallest optical implantable biodevice

26.04.2018 | Power and Electrical Engineering

Molecular evolution: How the building blocks of life may form in space

26.04.2018 | Life Sciences

First Li-Fi-product with technology from Fraunhofer HHI launched in Japan

26.04.2018 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>