Scientists have been studying and monitoring the Sand Andreas fault line that started moving about 30 million years ago and has since then horizontally slipped a total of 186-220 miles (300-350 kilometers). According to the United States Geological Survey (USGS), the San Andreas Fault Zone (SAFZ) is the main part of the boundary between the Pacific tectonic plate on the west and the North American plate on the east.
The fault consists of a system that is aside from the main fault. It has sub-parallel faults, such as in northern and southern California, that could take up motion between the two plates. So, which cities will be greatly affected when The Big One happens?
San Andreas Fault Line Map
The California Earthquake Authority wrote on their website that the San Andreas Fault line is one of the largest in the world that runs more than 800 miles from the Salton Sea to Cape Mendocino. It divides California into two in which San Diego, Los Angeles, and Big Sur are on the Pacific Plate, whereas Sacramento, San Francisco, and the Sierra Nevada are on the North American Plate.
The fault line runs deep under some of California's most populated areas, such as Daly City, Desert Hot Springs, Frazier Park, Palmdale, Point Reyes, San Bernardino, Wrightwood, Gorman, and Bodega Bay.
Meanwhile, experts warn that the southern San Andreas fault which slices through Los Angeles County and north of the San Gabriel Mountains could cause powerful earthquakes of up to magnitude 8 and would likely affect populated communities in Southern California.
Which Areas in California Are at the Greatest Risk of the Big One?
Experts have identified the areas in California that are at the greatest risk of getting hit by powerful earthquakes when the Big One happens. They used distance, elevation, location, and population data and focused on which cities would receive the highest number of casualties.
In the map presented by Haley Christianson, she only included those areas in California with a population of over 100,000 because they are the most likely to have more people affected by an earthquake compared to small towns. All in all, she was able to locate 71 cities in California with a population greater than 100,000.
The area with the highest population in Los Angeles, which is home to 3887,115 people, while the city with the lowest population is San Mateo with 100,361 people.
She classified the areas based on elevation and assigned them colors. Those in red were between -105 and 637 feet above sea level, while those in green lives 638 to 1,274 feet above sea level, and those living in an elevated area of more than 1275 feet above sea level were in green which mainly consists of mountainous areas and was given the lowest rank because fewer people would be affected by the earthquake there.
According to Christianson's map, most of the larger cities are in the Moderate Impact zone. This includes California's capital city of Sacramento, and the most populated city in the state, which is Los Angeles. Meanwhile, the High Impact Zone is mostly composed of low elevation areas that are 20 miles from the San Andreas fault line. There are no large cities in this zone because they would automatically be classified as Severe Impact if they are in the 20-mile buffer zone.
Christianson identified 15 cities that are ranked as Sever Impact with a combined population of 3.8 million people excluding areas with less than 100,000 people. In the event that a major earthquake happens, areas in this one will experience the highest amount of casualties, damage, and impact.
RELATED ARTICLE: San Andreas Fault: What Will Happen If It Breaks? When Will the Next California Earthquake Happen?
Check out more news and information on San Andreas Fault on Science Times.
