Potential Earthquake Impact in California, USA

Which areas in California are at the greatest risk of acquiring high negative impact from earthquakes? That's what I wanted to find out. Using elevation, distance, location, and population data I found the cities and general areas in California that would be most impacted by an earthquake from the San Andreas Fault.

Concerning this study, the focus on impact was specific towards levels of human impact (i.e. which cities would receive the highest number of casualties or have the highest number of people effected).

I was not surprised to see that none of the cities in the study were located in the high elevation areas. Of the 71 cities, only three of them were in the mid-elevation range. The three cities are Lancaster (Pop: 164,664), Palmdale (Pop: 159,649), and Victorville (Pop: 115,903).

There were a surprising amount of cities within 20 miles of the San Andreas fault line. Of the 71 cities, 15 were within that range. Of those 15 cities, both San Francisco and San Jose were included which boast populations greater than 800,000 people respectively.

All of the 'Little to No Impact' areas consist of mountainous, low populated areas. Most of the green sections are also a considerable distance away from the fault line. I would expect to see very minimal impact in these green areas.

The 'Small Impact' section takes up the greatest amount of space. I would expect to see only a small amount of impact in the yellow areas, based on their distance away from the fault line.

The 'Moderate Impact' zone is where most of the larger cities reside, which is okay. Both California's capital city (Sacramento) and highest populated city (Los Angeles) are in this zone. I would expect to see moderate impact in the light orange areas, and most of the danger comes from having such large populations in a fairly close proximity to the fault line.

The 'High Impact' zone is mostly composed of low elevation areas that are within 20 miles of the fault line. There are no large cities included in this zone because if a city were to be placed within the 20 mile buffer, it would automatically be categorized as 'Severe Impact.'

Areas labeled 'Severe Impact' are threatened the most by a possible San Andreas earthquake. There are 15 cities that are ranked as 'Severe Impact.' Combined, these cities have a population of around 3,800,000 people (this number does not even include cities with populations less than 100,000). In the event of a major earthquake, these cities would experience the highest amount of impact, damage, and casualties.

If I were to continue further analysis into earthquake impact in California, here are some of the things I would consider (in no particular order).

• All fault lines across the state, instead of just the San Andreas Fault.
• All cities in the state, instead of just those with a population greater than 100,000.
• Multiple-Ring buffers around fault lines with decreasing ranks the farther the distance.
• More in depth analysis into what makes an area particularly vulnerable to earthquake damage.
• More variables (Location of previous earthquakes, cities with high number of earthquake casualties, geology & how certain types of rock layers behave during earthquakes, etc.)

I want to personally thank UW-Eau Claire's Geography and Anthropology Department and, more specifically, Peter Strand for allowing me the opportunity to conduct this study and provide me with the knowledge and materials to successfully complete it.

Cities in California:

California Cities.  https://services.arcgis.com/Wl7Y1m92PbjtJs5n/arcgis/rest/services/California_WFL1/FeatureServer 

North American DEM:

Consbio (2014). 30 Arc-Second DEM of North America. H:\Documents\ArcGIS\Packages\d2198be9d2264de19cb93fe6a380b69c_674913\commondata\data0\

 San Andreas Fault Line:

Ferrar@FracTracker.org (2013). San Andreas Fault.  http://services.arcgis.com/jDGuO8tYggdCCnUJ/arcgis/rest/services/San%20Andreas%20Fault/FeatureServer 

California Boundary:

U.S. States (Generalized). H:\Documents\ArcGIS\Packages\USA States_69B4FAE9-93D6-4567-A173-31888E77455B\v10\states.gdb 

Population & Elevation Data:

Cohen, J. E., & Small, C. (1998, November 24). Hypsographic demography: The distribution of human population by altitude. Retrieved from  https://www.pnas.org/content/95/24/14009 .