Seismic Activity Essay, Research Paper
California has 200 or more faults capable of producing large earthquakes. Some
of the faults are hidden and some visible at the surface. The biggest
concentration of faults are in the San Adreas fault zone and the San Jacinto
fault zone. Because of California?s large amount of Fault lines the United
States Geological Survey, the California division of mines and Geology, the
California Institute and other agencies have developed the Southern California
Earthquake Center and TriNet Seismic network. This organization monitors the
earthquake activity. The seismographs are linked to a computer using a mix of
GPS and Landlines . The seismography records are sent to a computer within a few
minutes. The information is a available to the public via the Internet. Data at
this site is saved to a catalog that are searchable by various parameters. After
creating the project using ArcView GIS or Arc View 3D analyst, the next step was
to determine the project?s objective and scope. Once the data was obtained and
converted, maps could be created and analysis performed. The projects objective
was to ascertain whether there was a pattern to the earthquakes in Southern
California. The area chosen stretches approximately 67 miles by 50 miles. The
time frames was 6 months. The SCEC Data center Earthquake and Hypocenter and
Phase database was queried for data. Available search parameters were data about
magnitudes, start and end date, minimum and maximum depths and Longitude and
Latitude. A second site from Cal Tech and the USGS was also used. Time
measurements from the SCEC site were converted to Pacific standard time for use
with Cal Tech/USGS data. Latittude and longitude measurement in degrees from Cal
Tech site were converted to decimal degrees. The highway and street data (from
arcview) were used. The highways around the area was selected. Data from the
internet was used to determine where the faults were located. Using the line
tool, as each line was drawn the name of the fault was added to the table. Once
the map was completed, a 3d theme could be created. The 3d theme was created to
show the depth of the faults (z axis). In order to make a TIN theme the themes
from the 1st view was pasted into the 2nd view. A breakline theme was created
parallel to and on each side of an observed pattern of earthquakes perpendicular
to the San Jacinto fault. Using the earthquake point theme and breakline theme,
an inverse distance weighting contour was created. The contour theme was used to
create the TIN theme. The addition of this TIN caused the scene to rotate slowly
and then the patterns became evident. There appears to be a pattern of quakes
parallel to the San Jose and Cucamunga faults and perpendicular to the San
Andreas and San Jacinto faults. This article was a excellent source to show the
capabilities of Arc View GiS and Arc View 3D analyst. It also taught me a lot
about all the wonderful uses and purposes for GIS. GIS will be used a lot more