US: For the first time, scientists are using advanced technology and an innovative vessel to study, image and map the unexplored offshore Northern San Andreas Fault from north of San Francisco to the junction of three tectonic plates off Mendocino, California, US.
The team includes scientists from NOAA’s National Marine Fisheries Service, Oregon State University, the California Seafloor Mapping Program, the US Geological Survey and Woods Hole Oceanographic Institution. The expedition is sponsored by NOAA’s Office of Ocean Exploration and Research.
While the fault on land is obscured by erosion, vegetation and urbanisation in many places, scientists expect the subsea portion of the fault to include deep rifts and high walls, along with areas supporting animal life. The expedition team is using high-resolution sonar mapping, subsurface seismic data and imaging with digital cameras for the first-ever 3D bathymetric-structural map that will model the undersea Northern San Andreas Fault and its structure. Little is known about the offshore fault due to perennial bad weather that has limited scientific investigations.
“By relating this 3D model with ongoing studies of the ancient record of seismic activity in this volatile area, scientists may better understand past earthquakes — in part because fault exposure on land is poor, and the sedimentary record of the northern California offshore fault indicates a rich history of past earthquakes,” said Chris Goldfinger, co-principal investigator and marine geologist and geophysicist at Oregon State University in Corvallis, Oregon, US. “The model will also benefit geodetic studies of the build-up of energy to help better understand the potential for earthquakes.”