50 Fun Facts About San Andreas Fault

The San Andreas Fault's plates slide past each other about as fast as what grows on your body?

Fingernails grow at about the same pace as the plates move, a few centimetres a year. Over millions of years that crawl has carried rocks hundreds of miles along the fault.

Which city west of the San Andreas Fault is riding the Pacific Plate slowly toward San Francisco?

Los Angeles sits west of the fault, so it travels with the Pacific Plate while San Francisco stays on the continental side. In millions of years the two cities should be neighbours.

In Superman (1978), which villain targets the San Andreas Fault to sink California's coast?

Lex Luthor has bought up cheap desert, so sinking everything west of the fault would turn his land into prime coastline. One of his two missiles is sent astray by his bumbling assistant, Otis.

Despite the sinking-California myth, which way does land west of the San Andreas Fault really move?

Northwest is the heading, and the motion is horizontal: the two sides slide past each other, so there is nowhere for California to fall. The coast is shifting along the continent, never dropping off it.

When the San Andreas Fault ruptured in April 1906, what did most of the damage to San Francisco?

Fires did the worst of it: ruptured gas mains fed more than 30 blazes that burned for four days and nights. Up to 95 percent of the destruction is blamed on them, not on the shaking.

Which sports event was about to start in San Francisco when a 1989 San Andreas Fault quake hit?

The World Series was minutes from its third game at Candlestick Park when the shaking began. With so many fans already home to watch, rush-hour freeways were unusually empty, which saved lives.

Which action star plays a rescue helicopter pilot in the 2015 disaster film San Andreas?

Dwayne Johnson's pilot crosses a shattered state by helicopter and boat to reach his daughter. The film's magnitude 9 shocks outsize anything the real fault is thought capable of producing.

The San Andreas Fault is the boundary where the Pacific Plate grinds past which other plate?

North American Plate rock lies east of the fault and Pacific Plate rock west of it. Most boundaries of this sliding kind hide on the seafloor, which makes this one a rare example you can walk across.

On Point Reyes' Earthquake Trail, what structure shows how far the San Andreas Fault jumped in 1906?

A fence there stands in two halves about 16 feet apart, built by the Park Service to show the 1906 offset. The two sides of the fault lurched that far past each other in a single earthquake.

Which Italian tenor was jolted awake in San Francisco when the San Andreas Fault ruptured in 1906?

Enrico Caruso had sung in Carmen the night before, then fled the ruined city clutching a signed photo of President Theodore Roosevelt. He vowed never to return.

Which novelist covered the 1906 San Andreas Fault earthquake in San Francisco for Collier's?

Jack London hurried to the ruined city and filed an eyewitness report for the magazine. The house where he was born, near Third and Brannan Streets, was among the thousands of buildings lost.

Which city's double-deck freeway fell in the 1989 San Andreas Fault earthquake, killing 42 people?

Oakland's Cypress Street Viaduct pancaked, its upper level dropping onto the cars below. The road stood on loose soil, where the shaking was stronger and lasted longer than on rocky ground.

Which university's Memorial Church was badly damaged when the San Andreas Fault ruptured in 1906?

Stanford had to demolish a new library and gymnasium after the shaking, and some original features of its church and Quad were never restored. The campus had opened only 15 years earlier.

Along the east side of which desert basin, home to Indio, does the southern San Andreas Fault run?

Coachella Valley is a trough shaped by the fault together with the seafloor rift that runs up the Gulf of California. The fault follows the hills along its eastern edge.

The North Anatolian Fault, often likened to the San Andreas, passes about 20 km from which Turkish city?

Istanbul sits about 20 km north of Turkey's great fault, which is the same sideways-slipping kind as the San Andreas, with a similar length and speed.

Facing the San Andreas Fault during an earthquake, which way would you see the far side move?

To the right, whichever side you stand on, which is why streams and roads crossing the fault all jog the same way. In 1906 one road at the head of a bay was offset almost 21 feet.

Near Bombay Beach, the San Andreas Fault reaches its southern end at which salty desert lake?

Salton Sea is where sideways sliding gives way to spreading, as the crust pulls apart toward the Gulf of California. The modern lake only formed in 1905, when the Colorado River flooded in.

Which James Bond film has Max Zorin plotting to flood Silicon Valley using the San Andreas Fault?

A View to a Kill has Christopher Walken's villain planting explosives along the faults to drown his rivals and corner the microchip market. It was Roger Moore's seventh and final turn as Bond.

Which landmark collapses in a Nevada earthquake at the start of the 2015 film San Andreas?

Hoover Dam bursts when a previously unknown fault ruptures beneath seismologists testing a prediction model there. The disaster is the first link in a chain that soon reaches California's most famous fault.

About how long is the San Andreas Fault, which runs most of the length of California?

750 miles takes it from a desert lake near Mexico to a meeting of three plates off the redwood coast. Only one section breaks at a time, so no single earthquake rips the whole length.

What natural record suggests an 1812 earthquake began on the San Andreas Fault near Wrightwood?

Tree rings in trunks along the fault show sudden distress from that time, the strongest clue that the shaking began there. Earlier studies had blamed a fault nearer the ruined coastal missions.

What did PG&E stop building at Bodega Head in 1964 because the San Andreas Fault ran so close?

A nuclear power plant was to stand on the headland just west of the fault, and locals fought it for years. The abandoned foundation pit filled with water and was nicknamed the Hole in the Head.

Near Indio, what marks the line of the San Andreas Fault where groundwater is forced to the surface?

Palm oases appear where the fault lets underground water rise, feeding groves of native California fan palms. From the desert floor they show as a line of greenery along the hills.

Which San Francisco crossing lost part of its upper deck in the 1989 San Andreas Fault earthquake?

Bay Bridge traffic stopped for a month after a slab of the upper deck dropped onto the roadway below. Ferries across the water, gone for decades, were revived to carry commuters.

Plates slide sideways past each other at the San Andreas Fault, making it which kind of boundary?

Transform boundaries neither build new crust nor swallow old crust; the plates just grind past each other. The idea came from Canadian geophysicist Tuzo Wilson.

Both sides of the San Andreas Fault move sideways, not up or down, making it which type of fault?

Strike-slip motion carries one block sideways past the other. Geologists estimate the two sides have slid at least 350 miles since the fault was born.

Which 1989 San Andreas Fault system earthquake is named after a peak in the Santa Cruz Mountains?

Loma Prieta is the range's highest summit, though the rupture actually began five miles away on the far side of the fault. The magnitude 6.9 shock never broke the surface.

Which tiny town on the San Andreas Fault gets a magnitude 6 earthquake about every 22 years?

Parkfield's steady rhythm led scientists to forecast a shock before 1993 and pack the area with instruments. The earthquake finally arrived in 2004, eleven years late.

Near which headland does the San Andreas Fault end, at an offshore junction of three plates?

Cape Mendocino is where the fault turns west and stops. Past it, the plate boundary changes character, from sideways sliding to one plate diving beneath another.

Which Berkeley geologist first identified and named the San Andreas Fault, eleven years before 1906?

Andrew Lawson at first knew only the stretch near San Francisco; mapping the 1906 damage showed him the fault ran on into Southern California. He took the name from a valley south of the city.

Which theory of how faults cause earthquakes grew out of the San Andreas Fault's 1906 rupture?

Elastic rebound says rock on both sides of a fault flexes for decades, storing strain, then snaps back in seconds. Harry Fielding Reid worked it out from surveys made before and after the shock.

Which remote California grassland around Soda Lake is a classic place to see the San Andreas Fault?

Carrizo Plain is so dry and bare that the fault shows as a crisp line at the foot of the hills, with stream beds visibly knocked out of line where they cross it.

Which national park holds half of an extinct volcano that the San Andreas Fault carried 195 miles?

Pinnacles National Park keeps the western half of the volcano, while the matching rocks sit far to the south in the desert. The fault took about 23 million years to drag the two halves apart.

What do geologists call the central San Andreas Fault's slow, steady sliding without big shocks?

Creep lets the fault shed its strain a little at a time, so this stretch has produced no great earthquake in recorded history. The sections that stay locked are the ones that break violently.

Which mission town filmed for Hitchcock's Vertigo sits on the edge of the San Andreas Fault?

San Juan Bautista's old mission lies beside a fault scarp, and an unpaved stretch of the original El Camino Real runs along it. Earthquakes in 1800 and 1906 both damaged the mission.

Which long, narrow bay north of San Francisco fills a drowned stretch of the San Andreas Fault?

Tomales Bay is a straight, flooded trench along the fault, dividing the Point Reyes Peninsula from the mainland. The land on its far shore belongs to a different tectonic plate.

In which mountain gap near San Bernardino does the San Andreas Fault cross Interstate 15?

Cajon Pass owes its existence to the fault, whose movement opened the low gap between two mountain ranges. Two railroads and the freeway to Las Vegas all squeeze through it.

The great 1857 San Andreas Fault earthquake is named after which Army post, where damage was worst?

Fort Tejon gave the earthquake its name even though the rupture began far to the north and ran on for more than 200 miles. Only two deaths were reported in what was then thinly populated country.

Which sister fault of the San Andreas Fault runs beneath the football stadium at UC Berkeley?

Hayward Fault movement had shifted the walls of California Memorial Stadium by 13 inches since 1923, so by 2012 the stands were cut into four independent sections.

Which part of Mexico rides the Pacific Plate along with the land west of the San Andreas Fault?

Baja California was once joined to mainland Mexico, until the plate boundary cut in behind it about 12 to 15 million years ago. The widening gap became the Gulf of California.

Which subduction zone takes over where the San Andreas Fault ends and runs up to Vancouver Island?

Cascadia is a different beast: there one plate dives beneath another, which can produce magnitude 9 earthquakes. Its past ruptures may have set off shocks on the northern San Andreas.

What do geologists call the kink in the San Andreas Fault near Frazier Park, where it locks up?

The Big Bend makes the plates press together instead of sliding cleanly past, so strain builds there and mountains are squeezed upward. Large earthquakes recur on it roughly every 140 to 160 years.

What do geologists call the small lakes that fill sunken ground along the San Andreas Fault?

Sag ponds form where ground between strands of the fault drops and collects water. San Andreas Lake, which shares the fault's name, began as one before it was enlarged into a reservoir.

Which usually dry stream has a channel that jogs about 130 metres along the San Andreas Fault?

Wallace Creek drains straight across the fault, whose movement has carried its lower channel far out of line. It is among the most spectacular of the many creeks the fault has offset.

Which California mountains beside the San Andreas Fault are named after earthquakes?

Temblor Range takes its name from the Spanish for tremor and lives up to it: the fault runs along the western foot of the hills and has left visible fractures in the ground there.

Which fault meets the San Andreas Fault in the Antelope Valley but slides in the opposite direction?

Garlock Fault blocks shift to the left, the reverse of almost every other large fault in California. It runs east along the edge of the Mojave Desert toward Death Valley.

Which vanished ocean plate, named for islands off San Francisco, gave way to the San Andreas Fault?

Farallon Plate crust sank beneath the continent until almost none was left, bringing two other plates into sideways contact. Its last scraps survive as small plates such as the Juan de Fuca.

A circular sheep corral astride the San Andreas Fault reportedly ended up looking like what in 1857?

An S-shape was all that remained of the round pen, because one half slid sideways past the other. The same earthquake shifted stream channels by as much as 29 feet.

Which reservoir beside Interstate 280 fills a valley carved by the San Andreas Fault near San Mateo?

Crystal Springs Reservoir sits in the fault's rift valley yet stores drinking water for San Francisco. The concrete barrier holding it back came through the 1906 rupture with minimal damage.

Which San Francisco suburb is where the San Andreas Fault leaves land and heads out to sea?

Daly City's Mussel Rock is the fault's last landfall before it runs under the ocean, and the closest point on shore to where the 1906 rupture began.