Pacific Coastal & Marine Science Center
Coastal and Marine Earthquake Studies
|SHIPS: Seismic Hazards Investigation in Puget Sound
SHIPS Preparations at the USGS Marine Facility
February 10, 1998.
Preparations are underway at the USGS Marine Facility at Redwood City, California (near San Francisco). The equipment shown below will be shipped to Seattle and installed on the University of Washington Research Vessel Thompson.
Hal Williams (left) takes a break from work on the air compressors to talk to visitors. These compressors will deliver 600 cubic feet of high-pressure air per minute to the airguns. The compressors will be trucked to Seattle and mounted on the back deck of the R/V Thompson; they will supplement University of Washington compressors of equivalent size that are already onboard.
Kevin O'Toole works on the airgun gantry. The airgun array will be towed from this gantry, which will be mounted on the stern of the R/V Thompson. The gantry weighs about 20 tons and is made up of 10-inch diameter steel pipe. It is being specially made for the SHIPS survey. It was fabricated in Redwood City, and is shown here during final welding and assembly. Tarps obscure most of the structure because arc-welding can occur only during the infrequent breaks in the el nino rains. Kevin is working on one of the 16 hydraulic motors, each of which will be used to deploy an airgun. After being assembled and tested, the gantry will be disassembled, mounted onto three large trucks and shipped to Seattle.
Each airgun will be deployed by a separate winch on the gantry. This will allow each gun to be recovered and serviced independently without halting the data collection operations.
Parts for the airgun array that are being prepared for shipment to Seattle. Hal Williams has his hand on one of the larger airguns, and others can be seen in the basket near him. Airguns of various sizes will be used together to produce sound energy with an optimal frequency and energy.
February 17, 1998.
Welding of the airgun gantry is complete. Sixteen airguns will be attached to this gantry so they can be towed behind and fired from the R/V Thompson. Each coil of stainless steel wire that is mounted along the upper part of the gantry will have one airgun attached. The total tip-to-tip width of this gantry is 84 feet, and it weighs about 20 tons. The gantry was fabricated in Redwood City, California; it was assembled during breaks in the heavy, el nino rains. The gantry will be disassembled in late February, mounted on three heavy trucks, and shipped to Seattle, where it will be installed on the fantail of the R/V Thompson.
March 2, 1998.
The equipment is loaded on the truck and headed for the University of Washington.