{"id":7387,"date":"2024-09-22T23:08:56","date_gmt":"2024-09-22T23:08:56","guid":{"rendered":"http:\/\/www.backroadswest.com\/blog\/san-andreas-fault-in-san-bernardino-copy\/"},"modified":"2025-12-28T22:39:10","modified_gmt":"2025-12-28T22:39:10","slug":"san-jacinto-fault-tour","status":"publish","type":"post","link":"http:\/\/www.backroadswest.com\/blog\/san-jacinto-fault-tour\/","title":{"rendered":"San Jacinto Fault Tour"},"content":{"rendered":"\n
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Along with our other road trips along California\u2019s San Andreas Fault, this tour is a bit different as it visits a sister fault to the San Andreas – the San Jacinto Fault.<\/strong> The San Jacinto is a major parallel fault sharing much of the stored-up energy from the sliding action between the North American and Pacific Plates. The San Jacinto is just as active as the San Andreas and has had more recent earthquake events.<\/p> <\/div>\n<\/div>\n <\/div>\n

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\n Click image<\/strong> to watch Virtual Video Tour and see viewer comments.\nThen come back to get the rest of the story. <\/div>\n <\/div>\n \n <\/div>\n \n<\/div>\n\n\n
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Forward<\/h2>\n

For those that have watched the virtual video tour above, reading this blog post will give you more insight into the San Jacinto Fault. It also explains the touring route as well as more details about each stop that we\u2019ll visit.<\/p>\n

Like our other tours, see the Trip Map<\/a> for an interactive map of our touring route and a link to download the GPX file we created containing the places covered in the tour. Using Gaia GPS\u2019s Bedrock Geology<\/em> layer plots the paths of both the San Jacinto and San Andreas, making it easy to find many of the features described in this tour.<\/p>\n

Fault Terminology<\/h2>\n

This section on terminology is duplicated from our San Andreas Fault in San Bernardino post<\/a>. The difference with the San Jacinto is that it isn’t a plate boundary like the San Andreas. However, it shares all of the characteristics of the San Andreas and probably shares a lot of same stored-up energy of the two plates sliding past each other, as do other related faults in the L.A. area such as the Elsinore\/Whittier, Newport\/Inglewood, and Palos Verdes Fault zones. Then there’s the Eastern California (or Mojave) Shear Zone, which is a series of faults also similar to the San Andreas that cover the Mojave Desert and stretch up into Owens Valley.<\/p>\n

Throughout this tour, we\u2019ll be visiting places where we can see signs of the San Jacinto Fault. Those \u201csigns\u201d are what we call \u201cfault features\u201d. Here are some of those features explained.<\/p>\n

Keep in mind that the San Andreas and San Jacinto isn\u2019t just a regular fault like many others, it is a significantly large fault. It\u2019s actually a plate boundary<\/em> \u2013 the boundary between the North American Plate and the Pacific Plate. Both of these plates are experiencing what\u2019s called continental drift<\/em> and are literally sliding past (or rubbing against) each other very, very slowly. This edge or division between the two plates is the San Andreas Fault. Earthquakes occur when that sliding turns into a sudden jerk of movement. Explaining further involves a lengthy discussion of plate tectonics<\/em>, which is out of scope of this article. Learn more by Googling \u201cplate tectonics\u201d.<\/p>\n

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Global plate tectonics – San Andreas Fault pointed out<\/figcaption><\/figure>\n

The San Jacinto is known as a right-lateral strike-slip fault<\/em>. That means, if you are standing on one side of the fault and looking towards the other side, the land on the other side of the fault would be moving to the right. That means, the land on the Pacific Plate, which would include the Los Angeles area, is moving northwest. The land on the North American Plate, including the San Bernardino Mountains and Mojave Desert to the north, is either stationary or moving very slowly to the southeast.<\/p>\n

The fault isn\u2019t always a single line or deep \u201ccrack\u201d in the ground dividing the two plates. This is especially true with the San Jacinto as compared to the San Andreas. It can also be a \u201cfault zone\u201d. This zone can be anywhere from a hundred feet thick to 2-3 miles across. These zones consist of many factures or strands that are all related to each other.<\/p>\n

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Along the San Jacinto, the fault zone splits several times and becomes two separate faults, with one fading out. In the San Jacinto Valley and the town of Hemet, a split occurs where both faults on the map are labeled as the San Jacinto Zone. In the Anza-Borrego area though, each strand has separate names, neither of them with the word San or Jacinto. However, geologists recognize they are related to the San Jacinto.<\/p>\n

Here are some of the fault features we\u2019ll see in this tour:<\/p>\n