A
Guide to Earthquake Tourism Along the San Andreas Fault
The San
Andreas Fault, the boundary between the Pacific and North American tectonic
plates, caused California's worst disaster in recorded history: the 1906 San
Francisco earthquake. To this day, scientists are still learning about numerous
other seismic events that happened through the ages.
If you'd like to get to know this
mischief-maker known as San Andreas before it makes itself known as the
"Big One," you won't have to go very far. More than 700 miles of it
stretch from Northern California to the Salton Sea. There are plenty of places
in its southern segment known as the Mojave section, where you can see signs of
the movement of the two plates on either side -- the Pacific plate to the west,
and the North American plate to the east.
However, to chase down our faulty friend, you have to look closely -- and you have to know what to look for. The San Andreas Fault is more than a mile wide in some locations, and its signs may be as subtle as a dip in the road, a bend in railroad tracks, or a change in direction in a creek or a stream. Most of the places that you can visit along the San Andreas Fault show signs like these of the crustal bending and fault slipping, but there are places where you can actually see -- and touch! -- the fault itself.
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| Channel Islands National Park |
Channel
Islands National Park: To go back to
where it all started, take a look at the Channel Islands. The Pacific Plate's tectonic movement that brought it to meet the North American Plate directly
caused their formation in the Pacific Ocean. Their current orientation and
elevation are a result of tectonic plate movement over the last five million
years, but the plates haven't actually stopped. Since being formed, the islands
have rotated clockwise about 100 degrees, and continue to turn and rise.
Although signs of San Andreas are usually
more visible from a bird's eye view, you can get a great visual of the islands'
geologic uplift from the deck of a boat. Island Packers is a company that frequently runs
ferries from Ventura and Oxnard to the islands for day trips, camping
overnights, and sea cruises. Channel Islands Kayak Center also conducts kayak tours of the sea
caves of Anacapa and Santa Cruz Islands.
Carrizo Plain
National Monument: One of the most
important geological sites in the world is one of Southern California's
best-kept secrets: Carrizo Plain National Monument. Located 65 miles west of
Bakersfield, Carrizo Plain features an alkaline lake that remains dry most of
the year, but when wet, it's fed by Wallace Creek, a small stream that also
happens to be a world-famous section of the fault. If you climb up atop a ridge
along the Wallace Creek Interpretive Trail, you can see a very well defined
surface expression of the fault trace -- basically, the plate boundary, in
plain view. And because it's so arid there, the fault hasn't suffered any
significant erosion.
The signs of it are also relatively recent.
In the 1857 Fort Tejon earthquake (magnitude 7.9), the fault moved 30 feet at
Wallace Creek, making the stream channel look crooked, as it does today. And,
like the Channel Islands, it's still moving -- as much as 1.3 inches a year.
Here, you can get both incredible first-hand accounts and views of plate
tectonics in action.
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| Highway 14 |
Antelope
Valley: There are several sites in and around
Palmdale where the San Andreas Fault is accessible. Just north of Avenue S,
CalTrans bisected the San Andreas Fault to make way for Highway 14. Folded
layers of rock strata, which have been contorted by compressional forces, were
henceforth exposed. About 25 miles southeast of the roadcut, investigators also
cut the fault at Pallett Creek, creating a trench along the banks of the creek
where radiocarbon dating earned it the nickname "the Rosetta Stone of
Paleoseismology." You can walk right up to the trench and analyze the
layers of rock, like counting rings on a tree stump. You can even put your
hands on it or lean against it -- and wait for the earth to move.
Another
five miles east, conspicuous signs of the San Andreas Fault are visible at Devil's Punchbowl Natural Area, which lies
within the fault zone and has its own fault called the Punchbowl Fault. Here,
you can also see how intense pressures created dramatic folding of rock, and
how ongoing uplift action caused steeply tiled geologic formations. Explore
this county park on your own, or join one of the Punchbowl naturalists on a San
Andreas Fault tour, conducted every Sunday at 1 p.m.
San Gabriel Mountains: The San Andreas
Fault not only forms the northern boundary of the San Gabriel Mountains, but it
also formed the mountains themselves. To see evidence of it, visit the Big
Pines Ranger Station, which actually sits on top of the fault trace. Drive
along Big Pines Highway, and along the side of the road you'll see piles of
exposed rock that have been ground into dust by seismic activity over the ages
(a "fault gouge").
You
have San Andreas to thank for some of the recreational areas in the San
Gabriels, including the fault-bounded Jackson Lake in Angeles National Forest
and Lost Lake in
San Bernardino National Forest. Both were created by the fault, and both run
along the fault line. Lost Lake, a body of water formed in a sunken patch of
land between two fault strands, is particularly intriguing as no streams empty
into it. The water just comes up out of the fault, fed by deep natural springs.
Legend has it that this sag pond is a "bottomless lake" -- and gets
its water from the center of the earth. Fishermen still try to throw a line in
there to see what they can catch, even though the lake hasn't been populated
with fish in decades. But there's plenty of other wildlife to view and enjoy, including
some endangered birds like Bell's vireo, the southwestern willow flycatcher.
Inland
Empire: After the San Andreas Fault works its
way through the eastern San Gabriels along the Cajon Pass, it then traverses
the southern boundary of the mountains as it moves farther east. In Highland,
just outside of San Bernardino, you can observe the fault's handiwork at Plunge
Creek, offset by more than 300 meters over time. Several trenches were dug here
along the fault, and radiocarbon dating indicates that an earthquake offset the
creek sometime between the 15th and 18th centuries. If you'd rather take a look
at the San Andreas Fault without the danger of it lurking directly underfoot,
visit the Hall of Geologic Wonders
at the San Bernardino County Museum in Redlands, which houses actual
peels from the Pallett Creek portion of the San Andreas Fault.
In
the Coachella Valley, you can take your earthquake tourism to a whole new level
with a jeep tour with Desert Adventures orCovered Wagon
Tours. If it's not too hot out, hoof it and explore the fault on
foot at Mission Creek Preserve and Thousand
Palms Oasis, both of which are along the fault line. Enjoy the hot
mineral springs any season, day or night, at Two Bunch Palmsin
Desert Hot Springs, whose healing waters are reportedly released from deep
beneath the earth's surface by geological activity related to San Andreas.
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| Boiling mud pots at the Salton Sea |
The
Salton Sea: The Salton Sea usually attracts a
certain kind of visitor -- "snow birds" who come for the winter,
photographers building their portfolios, and birdwatchers hoping to catch a
migration or two. But for earthquake tourists, there are plenty of signs of the
San Andreas Fault here, running along the North Shore and down to Bombay Beach
and the State Recreation Area to the east of the sea, where it terminates.
There is a high potential for seismic activity the Brawley Seismic Zone --
especially with the nearby Imperial Fault -- but the most fascinating thing to
see here is the effect of the San Andreas Fault within the Salton Sea
Geothermal Field.
Near the Sonny Bono National Wildlife Refuge at the southern tip of the sea, you
can find the "boiling mud pots," where high heat emanates from zones
of partially molten rock deep below the Earth's surface, causing first violent,
and then tiny, eruptions. Over time, this active volcanic activity -- the only
active volcanoes in Southern California -- create lava domes, officially known
as The Salton Buttes. Earthquake swarms are common and persistent here, making
your chances for experiencing seismic activity while you're touring the San
Andreas Fault very high. Just be careful of the sulfuric steam being spewed out
of the mud pots as you explore. And watch where you step across the fragile and
cracked landscape.
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ABOUT
THE AUTHOR
Sandi Hemmerlein is a writer and photographer. In addition to
her work for KCET, she also contributes to Discover Los Angeles and Atlas
Obscura. Constantly on the prowl for new adventure, she spends most of her time
in L.A. nurturing her interest in birds, animals, neon, historic theaters,
puppets, trains, folk art, and stained glass. Sandi is also a field agent for
the Los Angeles Obscura Society, and she documents everything on her own
website Avoiding Regret.
https://www.kcet.org/travel/a-guide-to-earthquake-tourism-along-the-san-andreas-fault
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