yee@trident.arc.nasa.gov (Peter E. Yee) (03/17/89)
Charles Redmond
NASA Headquarters, Washington, D.C. March 15, 1989
Mary Hardin
Jet Propulsion Laboratory, Pasadena, Calif.
RELEASE: 89-33
NEW EARTHQUAKE FAULTS DISCOVERED WITH LANDSAT IMAGES
Several previously unknown geological faults, some of which
may be active, have been discovered in the central and eastern
Mojave Desert in California by geologists at NASA's Jet
Propulsion Laboratory (JPL), Pasadena, Calif., and Louisiana
State University analyzing images from an Earth-orbiting Landsat
satellite.
The strike-slip faults were identified by images taken by
the Thematic Mapper (TM) instrument on Landsat 5, which obtains
images simultaneously in seven bands at optical and infrared
wavelengths. Scientists used the TM images as a "map" which
pointed them in the right direction to locate and confirm the
faults in the field.
JPL's Dr. John Ford, who helped locate and verify the faults
in the field, said that "without Thematic Mapper images we would
not have found the faults and TM images may enable us to find
many more unmapped faults in the Mojave."
The newly observed faults are located in and near the
unpopulated Bristol Mountains and Cady Mountains. Scientists
have determined that the faults in the Bristol Mountains are
overlain by unconsolidated alluvial fan debris (gravel) and are
probably inactive. In contrast, faults lying to the west (Cady
Mountains) cut all deposits and are seismically active. The
faults all form part of a complex regional network of right-slip
faults that run between the Death Valley region and the San
Andreas Fault System.
The newly observed faults are much smaller and less active
than the San Andreas Fault but they all show evidence of a strike
slip, Ford said. During an earthquake, movement on a strike-slip
fault is dominantly horizontal and parallel to the trend of the
fault. Scientists are now trying to determine how the newly
observed faults fit into the regional structure in this part of
the Earth's crust.
The faults add new pieces to the geological puzzle of how
the Death Valley Fault zone and the San Andreas Fault system are
related in space and time. The presence of these newly observed
faults indicates that there are other yet-to-be discovered faults
in the area.
The research is being conducted by geologists, Dr. John P.
Ford, Dr. Robert E. Crippen and Dr. Ronald G. Blom of JPL and
Professor Roy K. Dokka of the Department of Geology and
Geophysics, Louisiana State University.
The project is funded by NASA's Land Processes Branch of the
Office of Space Science and Applications, Washington, D.C.