Observations and Results

Scientific Equipment

Multibeam Bathymetry

Uses sound to determine the depth below and alongside the ship at over 100 places at a time.

  Photos of the multbeam sensor (Reson 8101ER) and the installation of the moiunting pole on the R/V Endeavor.

 

"Chirp" Seismics

High-frequency sound bouncing off layers of sediment are used to make images that are a vertical slice of layers beneath the se floor.  We used three different "chirp" systems.

  Photos showing the Edgetech chirp 512i on deck and being deployed, and the Knudson minichirp used on the inflatable zodiac.  The third system, also a Knudson, is permanently mounted on the bottom hull of the Endeavor.

 

Sidescan Sonar

Towed "fish" looks sideways with sound.  It produces images that look like photos of the sea floor on either side of the "fish".

         Yellow sidescan sonar fish being deployed fom the zodiac and hanging from a cable off the R/V Endeavor.

 

Sediment Cores

We also used several instruments to sample the sediments at the bottom of the sea.

  Recovering and examining a gravity corer (model 2171), which uses a heavy weight to push a tube into the sediments, and a mutlicorer MC-400, which fills the four transparent tubes with samples of the sediment-water interface.  We collected 27 gravity cores, 4 multicores and 4 grab core samples.

 

Scientific Results

Multibeam map of Baie de Grand Goâve, west of Port au Prince, that images where the EPGF goes offshore.  The arrows point to the ridge formed by the fault. Bends in the faut are associated with areas of uplift and subsidence.  The chirp confirmed the location of the fault by imaging offset sediment layers.  We also collected evidence of additional active structures.

 

The cores document deposits from the sediment shaken loose by the earthquake. There were many slumps at the coast and below the sea, as well as other sediment disturbances caused by the earthquake. At left is a multicore showing event layers from the most recent earthquake and from earlier earthquakes. On the right are two cores from several kilometers apart showing the same two event layers.