San Andreas Fault
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50 free San Andreas Fault trivia questions with answers — science & nature quiz, new questions added Oct 2026.
The San Andreas Fault is the best-known crack in the Earth's crust, a long scar where two giant slabs of rock grind past each other for most of the length of California. It has levelled cities, moved mountains and inspired more disaster films than any other piece of geology. This quiz collects the fun facts people look for: how fast the fault moves and which way, where it starts and ends, the famous earthquakes of the last two centuries, the odd landmarks along its line, and the myths that films and comic-book villains have built around it. Questions run from easy to expert, each with a short explanation, so the quiz suits curious beginners, earth science students and Californians who live beside the fault every day.
30 of 50 questions with answers and explanations. Play the quiz
Q 01The San Andreas Fault's plates slide past each other about as fast as what grows on your body?
Fingernails
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.
Q 02Which city west of the San Andreas Fault is riding the Pacific Plate slowly toward San Francisco?
Los Angeles
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.
Q 03In Superman (1978), which villain targets the San Andreas Fault to sink California's coast?
Lex Luthor
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.
Q 04Despite the sinking-California myth, which way does land west of the San Andreas Fault really move?
Northwest
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.
Q 05When the San Andreas Fault ruptured in April 1906, what did most of the damage to San Francisco?
Fires
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.
Q 06Which sports event was about to start in San Francisco when a 1989 San Andreas Fault quake hit?
The World Series
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.
Q 07Which action star plays a rescue helicopter pilot in the 2015 disaster film San Andreas?
Dwayne Johnson
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.
Q 08The San Andreas Fault is the boundary where the Pacific Plate grinds past which other plate?
North American
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.
Q 09On Point Reyes' Earthquake Trail, what structure shows how far the San Andreas Fault jumped in 1906?
A fence
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.
Q 10Which Italian tenor was jolted awake in San Francisco when the San Andreas Fault ruptured in 1906?
Enrico Caruso
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.
Q 11Which novelist covered the 1906 San Andreas Fault earthquake in San Francisco for Collier's?
Jack London
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.
Q 12Which city's double-deck freeway fell in the 1989 San Andreas Fault earthquake, killing 42 people?
Oakland
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.
Q 13Which university's Memorial Church was badly damaged when the San Andreas Fault ruptured in 1906?
Stanford
Q 21What natural record suggests an 1812 earthquake began on the San Andreas Fault near Wrightwood?
Tree rings
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.
Q 22What did PG&E stop building at Bodega Head in 1964 because the San Andreas Fault ran so close?
A nuclear power plant
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.
Q 23Near Indio, what marks the line of the San Andreas Fault where groundwater is forced to the surface?
Palm oases
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.
Q 14Along the east side of which desert basin, home to Indio, does the southern San Andreas Fault run?
Coachella Valley
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.
Q 15The North Anatolian Fault, often likened to the San Andreas, passes about 20 km from which Turkish city?
Istanbul
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.
Q 16Facing the San Andreas Fault during an earthquake, which way would you see the far side move?
To the right
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.
Q 17Near Bombay Beach, the San Andreas Fault reaches its southern end at which salty desert lake?
Salton Sea
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.
Q 18Which James Bond film has Max Zorin plotting to flood Silicon Valley using the San Andreas Fault?
A View to a Kill
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.
Q 19Which landmark collapses in a Nevada earthquake at the start of the 2015 film San Andreas?
Hoover Dam
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.
Q 20About how long is the San Andreas Fault, which runs most of the length of California?
750 miles
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.
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.
Q 24Which San Francisco crossing lost part of its upper deck in the 1989 San Andreas Fault earthquake?
Bay Bridge
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.
Q 25Plates slide sideways past each other at the San Andreas Fault, making it which kind of boundary?
Transform
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.
Q 26Both sides of the San Andreas Fault move sideways, not up or down, making it which type of fault?
Strike-slip
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.
Q 27Which 1989 San Andreas Fault system earthquake is named after a peak in the Santa Cruz Mountains?
Loma Prieta
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.
Q 28Which tiny town on the San Andreas Fault gets a magnitude 6 earthquake about every 22 years?
Parkfield
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.
Q 29Near which headland does the San Andreas Fault end, at an offshore junction of three plates?
Cape Mendocino
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.
Q 30Which Berkeley geologist first identified and named the San Andreas Fault, eleven years before 1906?
Andrew Lawson
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.