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

for stuff like volcanoes and earthquakes.