Earthquakes at Sea Ranch?!
If you’ve spent time in California, especially along the coastal regions, then you most likely have felt it…EARTHQUAKE!
So you may be asking yourself as you get ready to book Sea Ranch Abalone Bay, “Sea Ranch is on the coast, does that mean we could have an earthquake here too🤔…😳…😱?”
Yes, indeed, it does! In fact this morning, January, 28,2021 there was a small rumble (magnitude 3.7) near Point Arena. The United States Geological Survey detected the quake at 8:25 a.m. with an epicenter 30.7 miles southwest of Point Arena, California. With a magnitude of 3.7 and depth of 2.49 miles, this quake could be felt near the epicenter but no damage was reported.
Not to Worry, Much
However, the number of earthquakes that have occurred in the area have not been that many nor that strong…so far.
According to EarthquakeTrack.com, there have been only 38 earthquakes along the Northern California Coast over the last year. The USGS database shows that there is a 74.17% chance of a major earthquake within 50km of Sea Ranch, CA within the next 50 years. The largest earthquake within 30 miles of Sea Ranch, CA was a 4.4 Magnitude in 2001. But if you are not used to them one may be one too many.
Nonetheless, after living through the 8.8 earthquake in Santiago, Chile that lasted 3 minutes in 201o, our family rarely flinches at anything under a 6.0 magnitude.
The San Andreas Fault
The San Andreas Fault is the sliding boundary between the Pacific Plate and the North American Plate. It slices California in two from Cape Mendocino to the Mexican border. San Diego, Los Angeles, and Big Sur are on the Pacific Plate. San Francisco, Sacramento, and the Sierra Nevada are on the North American Plate. And despite San Francisco’s legendary 1906 earthquake, the San Andreas Fault does not go through the city. But communities like Desert Hot Springs, San Bernardino, Wrightwood, Palmdale, Gorman, Frazier Park, Daly City, Point Reyes Station, and Bodega Bay l
After the San Andreas Fault leaves San Francisco, it plays tag with the California coast. The fault comes ashore at the Point Reyes Peninsula, Bodega Bay where they lie squarely on the fault and are sitting ducks, then at a stretch of the coast from Fort Ross to Manchester Beach. The rocks in this last segment are mostly sedimentary and were deposited in the Gualala Basin during late Cretaceous to Miocene time. We don’t know exactly where the Gualala Basin was when it started its trip north, but it was probably somewhere in southern California or Baja California.
Explore the Sea Ranch Earthquake Trail
One of our six self-guided Interpretive Trails is that of the San Andreas Fault Trail (pdf). The trailhead is located just above the Hot Spot on River Beach Road. Swales and hummocks (created by parallel faults) comprise the four ridges. Delight in the discovery of a sag pond. And make note of the broken trees and displaced/recaptured drainage channels from 1906 and earlier earthquakes. The trail also features historical remnants from 1890’s logging of original ancient redwoods (such as springboard notches and skid trails), as well as forest ecology of unique overstory, understory, and ground cover, as well as stump islands colonized by redwood sorrel (oxalis). Park at the Hot Spot and walk up River Beach Road to the trailhead.
Learn more about the Geology of the Sea Ranch and the San Andreas Fault
Places to See the Rocks
For the earthquake buff or rock hound, these trips within Sea Ranch may be the perfect vacation activity. Below are three areas you may want to explore in greater depth. The Pdfs attached here will help guide you and provide you with added information to make your discoveries more meaningful.
- Bluff (pdf): A geologic trip along the Sea Ranch bluff provides a good opportunity to visit these well-traveled rocks.
- Meadows and Hillside Terraces (pdf): The meadow and hillside at the Sea Ranch have been sculptured by wave action to form a series of wave-cut terraces during the last 500,000 years.
- San Andreas Fault in Sea Ranch: Walk along the San Andreas fault at the Sea Ranch and see ridges and sag ponds that were formed by movement along the fault.
- San Andreas Fault in Sea Ranch and Bowling Ball Beach, by Ted Konigsmark
It is important to remember, The Sea Ranch is private property. Non-residents should contact the Sea Ranch Association for access. However, as a guest of Abalone Bay enjoy your hike and exploration. Just pack your guest pass, your parking tag, a few snacks, and a water bottle. Oh and don’t forget your camera and geologic notebook too!
What to Do In Case of an Earthquake
Sonoma County is bounded on the west and the east by earthquake faults. For your emergency information, there are four active or potentially active earthquake faults are identified within the County’s boundaries.
Other Websites and Resources
Sonoma County Regional Parks:
Aerial Photographs of the California Coastline:
US Geological Survey:
For further resource visit Information http://www.geologictrips.com/index.htm