A RAPID response

The US National Science Foundation funded an NSF-EAR RAPID proposal (E. Calais, PI) for an integrated geodetic, geologic, and remote sensing field response to the January 12, 2010, Mw 7.0 earthquake in Haiti. The work is supported by the Geophysics Program (GEO/EAR) and the Americas Program in the NSF Office of International Science and Engineering (OISE). Technical support is provided by UNAVCO. Trimble, Inc., donated 6 sets of GPS erquipment to the project. Voila provided logistical support, safe locations and data communication for the continuous GPS instruments. The Bureau of Mines and Energy (BME), the National Center for Geospatial Information (CNIGS), the National Observatory for the Environment and Vulnerability (ONEV), the State University / School of Science (UEH/FDS), the Civil Protection AGency (DPC) provided essential collaboration and support. The field work included:
  1. Searching for, and possibly mapping, the surface rupture of the 01/12 event to help constrain a detailed slip distribution model. This work is coordinated by Paul Mann (Univ. of Texas, Austin), with the field assistance of Richard Koehler (Alaska Geological Survey) and performed in collaboration with imagery analysis by Carol Prentice (USGS Menlo Park). Preliminary results show that the earthquake rupture did not reach the surface, consistent with a slip inversion from radar interferometry data. Observations along the coastlines show subsidence in the area of Petit and Grand Goave (from sunken beaches) and uplift in the area of Legogane (from emerged coral heads), consistent with radar interferometry data. These observations corroborate those made by R. Bilham (Univ. Colorado) and W. Mooney (USGS). Historical accounts of the 1751 earthquake show a remarkable similarity in the areas of coastline subsidence along the Leogane to Petit Goave
  2. Surveying with GPS 30 geodetic benchmarks previously occupied in Haiti between 2003-2009 (E. Calais, A. Freed, G. Mattioli). These sites were the basis for a tectonic block model that showed ~7 mm/yr of interseismic strain accumulation on the EPGFZ. A new survey will provide 3D coseismic displacements that, together with geological mapping and radar interferometry will help determine the earthquake slip distribution. A total of 35 sites have been surveyed for 2 to 4 days each. All the sites located in the epicentral area have been recovered; only one site has been destroyed (Montrouis).
  3. Installing 6 continuously operating GPS stations to measure postseismic deformation processes, study interseismic strain accumulation, and possibly capture coseismic deformations from earthquakes to come. All stations are installed and operating. Locations are: Canape Vert (Port au Prince), Roussette (St Marc), Leogane, Petit Goave, Les Cayes, Jacmel. Data is open and made available via UNAVCO (www.unavco.org).
  4. Complementing the field effort by computing coseismic interferograms from radar data. This work is coordinated by Falk Amelung (Univ. Miami). Preliminary results from ALOS data (Japanese Space Agency) shows that coseismic deformation is concentrated between Carrefour and Petit Goave. First calculations indicate that the range change data is consistent with a combination of left-lateral strike slip and thrust motion on at least one north-dipping fault. The source appears quite compact, with up to 4 m of slip right under the eastern edge of the Leogane alluvial fan. This main be a zone of transpressional parallel to the main trace of the EPGFZ as recognized in a PhD dissertation by R. de Momplaisir in 1985.

In addition to the items described above, several other scientific efforts have taken place since the earthquake: