SCEC INSTANeT
News
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SCEC INSTANeT
News |
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SCEC scientists Dr. Chris Goldfinger (Oregon State University) and Dr. Mark Legg (Legg Geophysical) were aboard the Woods Hole Oceanographic Institute R/V Atlantis for 9 days at the end of March this year studying the active offshore San Clemente fault zone. Five submersible dives, aboard DSV Alvin, were made to a seafloor escarpment along the southern flank of the Navy Submarine Fan, located about 60 west of Punta Descanso, Baja California, Mexico. This location is where Scripps scientist, Dr. Peter Lonsdale, first discovered evidence of hydrothermal (actually a cold seep), including barite precipitates, tube worm colonies and clams, along a steep seafloor scarp associated with the San Clemente fault zone. During the last three dives, the scientists aboard Alvin found multiple seafloor fault scarps up to 2-3 meters high, vertical with possible evidence of sub-horizontal striations, in the turbidite muds and sands of Navy Fan. These scarps are likely associated with prehistoric earthquakes on the San Clemente fault, at least Magnitude=6 and greater. The Orange County News channel (OCN), which is channel 42 on Time-Warner cable TV in Huntington Beach, will be discussing these recent discoveries with Dr. Mark Legg, and showing brief videotapes of some of the scarps at 7pm on the program Prime Story, Tuesday, April 18. In addition, some SeaBeam maps of the seafloor bathymetry showing about 200 km of the lateral extent of the San Clemente fault zone studied during this and previous cruises will be shown. At last, marine geologists can confidently state that "We have seen the San Clemente fault, and it is truly awesome!" |
Phone 213/740-5843 Fax 213/740-0011 e-mail: SCECinfo@usc.edu |