How does this work?
San Onofre State Beach, California, United States

San Onofre Trail 3 to the Cristianitos Fault

A moderate beach hike along a geologically significant area in San Onofre State Beach, visting the Cristianitos fault.

Content
provided by
Viewed 16613 times
    This guide contains photos
 (1 vote)
Difficulty: Moderate
Length: 3.8 miles / 6.1 km
Duration: 1-3 hours
 
Overview: The Cristianitos Fault is a major earthquake fault line located less than one mile from the San Onofre nuclear power plant. This hike takes you on a 3.8 mile loop through San Onofre State Beach to the site of the fault line. Along the way, you’ll see the Monterey Formation, which holds most of the oil and gas deposits known in the LA basin and off the coast, as well as the abrupt end of the San Mateo formation at the fault line.

Tips: Day use parking at San Onofre State Beach is $15 or you can use your annual day use parking pass.

The beach has stretches that are completely covered with cobblestones. Shoes with good ankle support would be advisable.

There isn't much shade, so bring a hat and wear sunscreen.

There are restrooms and water along the bluff campgrounds, but none on the beach. Bring water.

The bluffs are unstable and dangerous. Stay on marked trails.

Points of Interest

Parking
map

Parking

You can park in any unnumbered space along the bluffs. The numbered are reserved for camping.

For this hike, park near Trail 3.
Junction
map

Turn right down Trail 3

Trail 3 is one of six trails leading down to the beach from the bluffs.

Watch your footing on the downhill sections. The loose gravel can make it hazardous.
map

USGS Benchmark

Look for this USGS benchmark at the final turn before reaching the beach.
Information
map

Monterey Formation

Here you can see a section of the Monterey Formation exposed. This shale formation contains most of the oil and gas deposits in the LA basin. The oil platforms off the coast of Southern California drill down into this formation.

It's exposed here because of the activity on the Cristianitos Fault.
Viewpoint
map

The Cristianitos Fault

The Cristianitos Fault is easily found. The bluff to the north is identified by the wide light-colored band known as the San Mateo Formation. This band abruptly ends here.

Scramble 10-15 yards up this hill and see the strike plate of the Cristianitos Fault.

The layer of rubble above the San Mateo Formation, as well as the alluvial material above that, has been undisturbed. Geologists have dated that material to be 125,000 years old, so we know that the fault has not been active for at least 125,000 years.

This is why there were able to build the San Onofre nuclear plant less about a mile away from the fault line -- the fault is essentially "dead."

When you finish exploring the fault, head back south down the beach, retracing your steps.
Junction
map

Trail 1

Heading back, take Trail 1 up to the bluff and experience this area from a different perspective.
Junction
map

Stay right

The spur to the right leads to another parking area. Stick to right on the main trail here.
Junction
map

Bluff Trail

At the top of the bluff you have two options. You can walk along the pavement and the campsites, or follow this dirt trail which extends along much (but not all) of the bluff.

Take a right here the nicer bluff trail back to your car.
Restroom
map

Restrooms

Junction
map

Trail 2

An alternative route to the beach. If you want to shorten this trip, start here instead of Trail 3.
Restroom
map

Restrooms

Campground
map

Campsites

These are typical of the bluff campsites. There aren't very rustic, especially given their proximity to the freeway, but they all include a fire ring and picnic table, and you are a short hike from the beach.
Restroom
map

Restrooms

Pictures in this guide taken by: jeffhester, arellano21

San Onofre Trail 3 to the Cristianitos Fault Trail Map


POIs: numbers | icons View large Trail Map

Have an iPhone or Android?

  • Map your route while you move
  • Add trip photos to your map instantly
  • Share trips right from your phone
  • Find and follow trips from other travelers

Available For:
iPhone | Android

About the Author

jeffhester
jeffhester
20 guides
view jeffhester's profile
I live in Southern California, where most people are completely unaware of the hundreds of great hiking...

San Onofre Trail 3 to the Cristianitos Fault 3 Day Forecast

Extended Forecast
How To Get There
Get directions from: