USGS has several types of soil.
USGS soil types are a way to measure the potential of any location for shaking during earthquakes. Government geologists determine the kind of soil by examining results from a number of samples taken 30 feet below the surface with a special probe. According to the USGS (United Stated Geological Survey) experts, "Soil type greatly influences severity of damage from earthquakes, Does this Spark an idea?
USGS Soil Type A
Soil and rock at locations transmit shock waves from the epicenter of an earthquake which are measured in shear-wave velocity, or Vs. High Vs readings represent more stable locations, lower ones show where sever shaking will be a factor. USGS Soil Type "A" has a Vs rating of 1500 meters per second, meaning it will experience the least shaking during an earthquake. Type "A" locations feature "un-weathered intrusive igneous rock," according to the USGS experts. Soil type "A" is found in the Bay Area of San Francisco and represented by the color blue on the USGS map, where it is grouped with the second most stable type, "B."
USGS Soil Type B
USGS soil type "B" has a Vs rating of between 750 and 1500 meters per second. This slower rate of shock wave transmission makes it a good location for buildings of any kind. This type of soil is found in areas with ancient rocks between 64 and 245 million years old, including Franciscan bedrock, volcanic rocks and many locations with Mesozoic bedrock, such as the San Francisco Bay Area, represented by the color blue on the USGS map.
USGS Soil Type C
Areas with USGS soil type "C" have Vs ratings between 350 and 750 meters per second. Features of these locations include quaternary sands, limestone, sandstone, serpentinite, Franciscan melange and older mudstones between 24 and 64 million years old. Areas are represented by the color green on the USGS map. Locations with type "C" include the Point Reyes National Seashore and the majority of the San Francisco Bay Area.
USGS Soil Type D
USGS soil type "D" has a Vs rating of between 200 and 350 meters per second. It encompasses locations with features like muds, sands, silts, quaternary muds and gravels. As might be expected, this soil type is a less stable base during earthquakes, since it transmits shock waves quickly. Areas with USGS soil type "D" are represented by the color cream on the USGS map. Locations include the Rio Visto area of California.
USGS soil type E
USGS soil type "E" is the least stable kind and fastest to transmit shock waves at a Vs rating of 200 meters per second. Locations USGS soil type "E" with feature mud which is saturated with water and locations with artificially filled or raised land. This kind of soil experiences severe shaking during an earthquake and is the least suitable location for building projects. Areas with this type of soil are indicated by the color pink on the USGS map.
Tags: meters second, represented color, soil type, locations with, shaking during, shock waves, Soil Type
