Hello.

I'm standing on one of the most active parts of the Earth's surface.

It doesn't look like much when you're on the ground, but when you get in the air, it's a whole different story.

♪ Welcome to the San Andreas Fault of California.

♪ Doug, voice-over: This gash in central California marks the boundary between two of Earth's tectonic plates.

The San Andreas fault is not always noticeable on the Earth's surface, but it runs non-stop for nearly 800 miles, all in California.

Movement on this notorious fault over millions of years has sculpted a very unusual strip of land along its length, and there are many great, even surprising places that I can show you.

I've lived on this fault for most of my life, so I consider it my fault.

This is Doug's Geology Journal.

We're gonna go up and down the San Andreas Fault.

Let's go explore.

♪ ♪ Announcer: Funding for this program was provided by the National Science Foundation.

♪ [Loud sigh] Oh, where's the bus?

Wonder when it's coming.

Oh, never.

So, I'm sitting at a bus stop at an interesting place called Bombay Beach.

Lot of artwork here.

Doug, voice-over: The San Andreas Fault technically begins right about here below the tiny artist enclave of Bombay Beach on the Salton Sea.

From here, the fault goes northwest past Palm Springs into the mountains north of Los Angeles, then into the Coast Range towards the San Francisco Bay.

It skirts San Francisco to the West, then stays close to the coast until it ends just offshore at Cape Mendocino.

Often, the fault line hides below the surface, covered over by loose sediments like at Bombay Beach.

It runs along the east side of the Salton Sea, but there's no gash or anything out on the landscape.

It's just pretty flat out there next to the sea, but if the bus doesn't come within 2 hours, I don't know what I'm gonna do.

[Loud humming] Doug voice-over: Well, if the bus never comes, This would be a great way to leave Bombay Beach and see the San Andreas Fault from the air as it goes north.

Pretty soon, just east of Palm Springs, you would come to unlikely pockets of palm trees In the otherwise very dry desert landscape.

You might ask yourself, "What are they doing here?"

This is a really amazing place where some native palm trees are growing in an incredibly dry wash. And besides the palm trees, there's nothing but low shrubs.

Is this oasis in the Coachella Valley Preserve a mirage?

Nice and cool in here.

It's amazing.

It's so hot in the sun and in here, it's like 20 degrees cooler.

Incredible.

Something happened to let enough water collect to let these beautiful palm trees grow.

And that something is the San Andreas Fault.

So, right here, the San Andreas Fault goes right under my feet and under those palm trees.

And because the ground is all ground up and cracked apart there, there's a lot of water seepage in the ground.

Doug, voice-over: The water collects at the fault line because it is blocked by the Pacific Plate as it slides by the North American Plate.

Occasionally, the plates lurch abruptly, causing violent earthquakes.

But the plates don't always jerk past each other in earthquakes.

Sometimes they move very slowly.

I'm on the creeping segment of the San Andreas Fault.

The San Andreas Fault is right underneath me here.

Doug, voice-over: This creeping part of the fault is in central California, near a tiny town called Parkfield.

This is called the creeping section because the two plates on either side of the fault are actually creeping by each other, so slowly that most of the time, they don't even register any earthquakes on the seismic instruments.

Doug, voice-over: The people of Parkfield are well aware that the San Andreas fault runs right by their town.

Let's see, now, I know the San Andreas Fault is somewhere around here.

Oh!

That way.

Cool.

Doug, voice-over: But what's this about being the Earthquake Capital of the World?

Every 20 to 25 years or so, there is a pretty big, like, 6.0 or bigger earthquake along this creeping section.

And that's because, as it creeps along like this, it's building up stress in the crust between the two plates, and then eventually it breaks.

But meanwhile, the two plates are just creeping by each other really slowly.

So, why is the San Andreas fault creeping along kind of like a serpent right here?

Well, scientists drilled into the fault some years ago and actually found pieces of rock called serpentine.

Now, serpentine is a rock that's very, very slippery and it's partly causing those two plates that come together to actually just creep by each other, kind of like a serpent.

♪ Doug, voice-over: From Parkfield, we go south for a while on a road that follows the San Andreas Fault in a valley that the fault created.

Soon, the road and the fault meet the busy Route 56.

This intersection was the scene of a tragic accident now commemorated by a memorial.

Right here is where James Dean, the famous young actor, was killed in a car crash in the year 1955.

He was only 24 at the height of his career.

And it just so happens that the San Andreas Fault runs right under this highway right here in this area.

♪ Doug, voice-over: Not far from the James Dean Memorial, the San Andreas Fault, goes through the Carrizo Plain, where it has carved the striking gash seen in most textbooks about earthquakes.

But just beyond the Carrizo Plain, it makes a bend, a curve with dramatic effect on the Pacific Plate.

I'm standing on the San Andreas Fault where it is at its highest point, and it's really cold up here.

And the mountains here are a very high mountain range.

They get over 10,000 feet, and so it's--it's a very unusual part of the fault, and it's beautiful.

Doug, voice-over: This is the San Gabriel Range, just north of Los Angeles.

The fault is actually turning a bend here.

So, as the Pacific Plate kind of rounds this bend, it's crunching up these mountains higher than they would be normally.

So you get up here and it's very dramatic as the fault climbs up into these mountains and runs right along the back side of the mountains.

Doug, voice-over: The bend in the San Andreas Fault actually affected the Pacific Plate all the way to the coastal city of Santa Barbara, 40 miles away.

This is Santa Barbara, the beach, and when you're on the beach here, look out at the ocean, you don't look West like you do on most of the West Coast.

You're actually looking south, due south.

Doug, voice-over: That's because a chunk of the Pacific Plate has been rotated 90 degrees by movement on the San Andreas Fault.

Amazing things happen to the land here because of movement on the fault.

This road runs east-west now.

Well, there was a time when this road, if it was here millions of years ago, would have been faced north-south.

I better draw you a picture to show you how that happened.

Doug, voice-over: As the Pacific Plate ground northwest along the North American Plate, a big chunk of crust, including the ground where Santa Barbara is now located got bogged down at its north end as it rounded the bend in the San Andreas Fault.

This made the south end swing outward, and over tens of millions of years, it has rotated 90 degrees so far.

Even the gorgeous mountains rising high above Santa Barbara were caught up in this rotation.

We're at the top of the Santa Ynez mountains, which rise so dramatically behind Santa Barbara.

They rise up to about 4,000 feet, and they're so high because the Pacific Plate is being squeezed as it's going around this turn and rotating this piece of crust which is causing these mountains to be pushed up a little higher than they would be normally.

♪ Torquing the crust and building mountains are signatures of movement on many parts of the San Andreas Fault.

Another is the hauling of rocks on the Pacific Plate a long way from where they formed.

There you are.

I'm hiking in the Pinnacles in Pinnacles National Park central California.

The San Andreas Fault is right behind these rocks.

So this side of the fault is the Pacific Plate, and these rocks are amazing.

They actually didn't form right here.

They were created about 200 miles to the south, and then the San Andreas Fault movement wrapped them up here on the Pacific Plate to where they are today.

The other thing about these rocks is they're volcanic.

They're not actually a volcano.

They're a big bunch of erupted materials that came out of an ancient volcano.

So I'm gonna draw a picture to show how these rocks had moved 200 miles from the south up to this place here at Pinnacles National Park.

Doug, voice-over: The ancient volcano was a giant stratovolcano that rose on the Pacific coast millions of years ago.

It erupted many times, piling up lava and ash flows on the ocean floor.

Then, 23 million years ago, the Pacific Plate started moving north along the newly created San Andreas Fault.

It took a big chunk of the volcanic field north with it, and it ended up at Pinnacles National Park.

Oh!

So, another fabulous thing about being in the Pinnacles-- is you can see condors, and there's one right up there.

Wow!

Hello!

Can you see me?

Yes!

So, here the Pacific Plate is pretty wide, the part that's on land.

The San Andreas Fault is just on the other side of these boulders and then it's probably about 20, 30 miles to the coast from here.

So, it's a nice wide stretch, and all of that land is moving north.

♪ Doug, voice-over: Due west is the peninsula of Monterey where the bright granite rocks contrast deeply with the Waters of the Pacific.

The granite is rare on the coast, but Californians may feel like they've seen this rock somewhere else, and they have.

I'm at Lovers Point in Monterey.

It's a great name because lovers come here all the time.

And I must admit that I came here today because I'm in love with this granite rock.

And this rock is very special.

If you ever been to Yosemite National Park in the Sierra Mountains, you see a lot of beautiful granite rocks.

Most of the rock in Yosemite National Park is granitic.

Well, this granite right here actually came from the Sierra Mountains, the same mountain range as Yosemite.

[Waves crashing] This rock, it formed at the same time and from the same process, but the San Andreas Fault came along and started moving the Pacific Plate north.

It ripped off these rocks from the Sierra Mountains and brought them up here about 180 miles to the north, where they are here right here now at Lovers Point and I can give them a nice hug.

Doug, voice-over: And then I can go to the other side of the Monterey Peninsula to Carmel to sample a gorgeous by-product of the far-traveled granite.

I'm sitting on a white sand beach in Carmel.

White sand beaches are rare in California, and this one is white because the granite rocks around here are eroding from forming this beach in the sand.

And when it arose, it's white.

So, I'm gonna go see how-- Hey there!

I'm gonna go see how cold the water is.

Doug, voice-over: The ocean here is freezing.

That's no secret.

But around the peninsula and Monterey Bay, there lurks a deep secret unseen from the shore.

This is a harbor in the town of Monterey.

It's on Monterey Bay and in the middle of the bay is one of the deepest underwater canyons on the entire planet.

It's over 5,000 feet deep.

It's right out there, and it's--actually gets a lot deeper as you get further out to sea.

Doug, voice-over: But a look at a map reveals a problem.

What created this super-deep gulch?

There should be a mighty river emptying into the bay where the canyon starts, but the biggest river around is the Salinas River, which is not a major river.

This river is just too shallow.

It just doesn't carry enough sediment or power to carve such a deep canyon.

So, the Salinas River, though, at one time, was extremely way more powerful than it is today.

Doug, voice-over: And that's when the Salinas River was actually connected to the Colorado River-- Colorado River's entire watershed with all its sediments coming out of the whole western United States, drained out to the ocean through this waterway, carving the massive underwater canyon that is now here in Monterey Bay.

But that was 20 million years ago when the Salinas River was located some 200 miles to the south.

Since then, the Salinas River, the canyon under Monterey Bay, and the granite rocks by the bay all wrapped it up on the Pacific Plate by movement along the San Andreas Fault.

♪ Doug, voice-over: Running north from central California, the San Andreas Fault climbs into the Santa Cruz Mountains, Where fault movement helped create something very special.

This is the Santa Cruz Mountains here, and the San Andreas Fault runs right through this mountain range.

In fact, it created this mountain range, and one special thing that happened as a result of that is an amazing redwood forest.

Redwood trees are a very unique and rare ecosystem.

This ecosystem here along the California coast was created by the upward movement along the San Andreas Fault that created these mountains, and then climatic forces coming in off the ocean meet with the mountains, and then they created the perfect conditions for redwood trees.

[Waves crashing] Doug, voice-over: Below the forest, all along the coast, the mountains give way to flat, wide terraces.

The town of Santa Cruz was built on a terrace.

This is Santa Cruz, it's one of my favorite towns in the whole world.

I went to college here, got my geology degree.

So I always love to come back here.

And Santa Cruz is built on a terrace.

And when you're standing on one of these flattop terraces along the coast, you're actually standing on what was once the floor of the ocean.

This used to be the ocean floor, and sea level at one time, was way higher than this.

And the reason these terraces exist is because sea level has been going up and down hundreds of feet during the ice ages.

The terraces are also growing out of the sea really slowly, and that's because of the movement of the Pacific Plate, grinding along the North American Plate here.

So, it's a combination of the fault movement and sea level going up and down that creates these beautiful terraces.

So, here in Santa Cruz, one of the best surfing spots on the entire planet.

And the reason why the waves are so great here for surfing is because of this terrace.

♪ So, it's got this huge cliff, and the waves are coming around this terrace and they're getting focused right here on this awesome surfing spot.

♪ Doug, voice-over: Sea level is going up again, but this time it's not because of the ice ages.

It's because of human-induced climate change.

This is where the road used to be out here, but the cliff has been eroding really fast along here, and now the road is way back there.

And the reason it's eroding is because of sea level rising because of climate change.

Doug, voice-over: The San Andreas Fault heads north from the Santa Cruz Mountains and drops into the San Francisco Bay Area.

It runs below San Andreas Lake, for which the fault was named.

Then it heads offshore, just before it reaches San Francisco.

This bridge is-- guess what bridge this is?

Right.

It's the Golden Gate Bridge, and San Francisco is just past the bridge.

The San Andreas Fault in this area runs just offshore here.

It runs along the ocean floor as it goes past San Francisco.

San Francisco is world famous for being a very hilly city, and the reason it's so hilly is partly because of movement on the San Andreas Fault over millions of years.

Doug, voice-over: The fault doesn't stay offshore for long before coming back onshore at a place where few people are thinking about faults or earthquakes.

This is definitely the life.

I'm here on a beach in Northern California.

It's a sunny, warm day.

Everything's perfect as long as there's no earthquake.

This is Stinson Beach, just north of San Francisco, and it's a very beautiful beach, very popular beach, because it's so close to San Francisco.

And it just so happens that it's sitting right on top of the San Andreas Fault.

Doug, voice-over: At the end of the beach is a telltale sign that an earthquake fault is nearby.

Some of these gigantic rocks are serpentine, and as we have seen, serpentine and faults often go hand-in-hand.

The serpentine here is similar to the rock in the creeping section of the San Andreas near Parkfield, but these rocks are way bigger on the surface here, and the earthquakes are much larger, too, like the devastating San Francisco earthquake of 1906 which was centered just a few miles from this beach.

Visitors to Point Reyes National Seashore can still see the effects of that enormous earthquake today.

So this is that famous fence that got offset in the 1906 earthquake.

This part of the fence is on the North American Plate, but then the big earthquake happened... and the fence was split, and this part of it, which is on the Pacific Plate, moved 15 to 20 feet in a split-second.

That's incredible.

Doug, voice-over: So, what is a split second?

How fast did the fault rip open?

A lot faster than I can run, that's for sure.

Consider that the fastest commercial jets cruise at about 550 miles per hour.

Well, faults break at 8,300 miles per hour, 15 times faster than a speeding jet.

Continuing our journey along the San Andreas Fault, if you are flying north out of San Francisco, you might soon spot the long, straight Tomales Bay, which was carved by movement along the fault.

The fault then begins hugging the coastline.

Well, this sure is gorgeous.

This is a place where the San Andreas Fault runs right along the coastline.

So, the Pacific Plate is really the Pacific Ocean, which is really what most of the Pacific Plate is.

In fact, there's only two places on the entire Pacific Plate that are on land.

And that is here in California on the coast, and the other place is all the way over on the other side of the Pacific Plate, and that's New Zealand.

Right now, we're on the North American Plate and we're about to step onto the beach and be on the Pacific Plate.

♪ Ta-da, the Pacific Plate ♪ What an amazing beach.

Gosh!

♪ Doug, voice-over: North of Bodega Bay, movement on the San Andreas Fault has again helped create wide terraces that end dramatically at shoreline cliffs.

Toward Point Arena and this lighthouse, the cliffs are made out of sedimentary rocks.

There is no serpentine in sight, which tells me that the San Andreas Fault does not run close to the ocean here, and in fact, it cuts a straight valley into the forested mountains a few miles inland.

♪ Heading north, Highway 1 goes through the small town of Manchester where it's time to visit Alder Creek Beach to meet up with the San Andreas Fault for the last time.

But first, a selfie with my fault.

Right back there is the San Andreas Fault on that hillside, cutting right up that hill.

So, I'm gonna do a selfie and point right at the fault.

Let's see, right there.

Smile!

[Shutter clicks] Doug, voice-over: The cliff at the beach reveals the furthest point north where you can actually see the fault on land.

There's these grayish, greenish rocks right here, which is the Pacific Plate, and over here are some brownish rocks and that's the North American Plate.

So, I think I'm just gonna climb up the San Andreas Fault!

OK, Pacific Plate foot... North American Plate, Pacific Plate, North American Plate, Pacific Plate.

Doug, voice-over: And then the fault goes into the Pacific Ocean, where it eventually ends about 100 miles north of here.

Bye, San Andreas Fault!

This is where the San Andreas Fault leaves the land and goes offshore.

Bon voyage!

Bye, San Andreas Fault!

Have a good voyage!

♪ ♪ ♪