GMEG - Geology and Geophysics
|Geophysics is "the study of the earth's physical properties and of the physical processes acting upon, above, and within the earth. It includes seismology, geomagnetism, meteorology, and oceanography" (Collins English Dictionary, 2003). About half of the Geology & Geophysics staff is involved in geophysical research and mapping. Mapping of the structure below the land surface is conducted using deep geophysical investigations measuring seismic, gravity, natural magnetic, and electrical properties of rocks. When combined with traditional surface geologic mapping, these geophysical models can help delineate three-dimensional (3D) interpretations of subsurface rock units and structures, such as the geometry of faults, sediment-filled basins, igneous intrusions, and other features that may have no apparent expression on the surface. G & G scientists have used geophysical mapping methods to model groundwater resources, geothermal energy resources, and the geometry of earthquake faults in tectonically active regions, such as along the San Andreas Fault system, the Mojave Desert Region, and along the eastern Sierra Nevada region.
|Example of a gravity field map used to characterize the geometry of faults, bedrock structure, and alluvium-filled basins in the southern San Francisco Bay region. Click on images for a larger view.|
| Learn about the "Geophysical Unit of Menlo Park" (GUMP).
Learn about the USGS Rock- and Paleo-magnetics Laboratory - Facilities and Equipment
Located on the US. Geological Survey campus in Menlo Park, CA
See selected examples of geophysical mapping and modeling (gravity maps, magnetism maps), learn about the truck towed magnetometer, electrical methods in geophysics, Gravity Base Stations of the World (part of the World Relative Gravity Reference Network [WRGRN])
See selected references by G & G scientists about:3D modeling, geophysical studies, gravity mapping, magnetism and paleomagnetism, groundwater and geothermal resource studies, buried mineral deposit assessments
|Example of a magnetic field map used to characterize the geometry of faults, bedrock structure, and alluvium-filled basins in the southern San Francisco Bay region.|