By Rick Wilson
Engineering Geologist, California Geological Survey
"The difference between truth and fiction: fiction has to make sense."
-- Mark Twain
Even if truth is stranger than fiction, sometimes movies blur the lines between the two.
Whether we view movies as an educational experience or simply entertainment, we all value the ability of movies to help us escape reality for a little while. Sometimes, however, because a movie uses science and technology as a backdrop, the story will be more believable to its viewers, helping them form opinions that might affect their view of reality and, ultimately, the way they live their lives.
Some moviemakers have relied on a perception of reality that has been fostered over the years by, in many cases, watching other movies. They do this instead of developing equally interesting story lines based on the truth.
This is the case with the upcoming NBC miniseries entitled “10.5,” a reference to an imminent earthquake of that magnitude. The four-hour miniseries airing over two nights, May 2-3, is a melodrama starring Beau Bridges, Kim Delaney, and Fred Ward. The story is about a number of large earthquakes that devastate the western United States and the efforts of the government to stop the "Big One" that threatens to send part of California off into the ocean.
Escaping reality, we do get to see the destruction of some well-known West Coast landmarks. However, the overall plot and some of the other special effects in “10.5” play on a number of misconceptions and urban legends regarding earthquakes that have a long history in Hollywood (though Canada seemed to be the filming location of most of this movie).
As a matter of fact (so to speak), this movie incorporates several of the biggest myths that scientists have been trying to dispel about earthquakes in California. These include California falling into the ocean, holes opening up and swallowing people and things, and the use of nuclear weapons to stop or start an earthquake.
A movie like “10.5” does make people wonder just what is fact and what is fiction, and gives scientists the opportunity to address these myths once again. It is important to note that although we find in nature that things once thought to be impossible sometimes are found to be true, we are getting better at determining what is realistic and what is not. Here we will try and distinguish between what is science fact and what we consider science fiction.
Can a magnitude 10.5 earthquake really occur?
Based on our existing knowledge of plate tectonics -- where the Earth's crust is broken into many solid "plates" that typically collide and push under (subduct) or scrape by each other to create the largest earthquakes -- there is not a large enough single crustal plate boundary to create a magnitude 10.5 earthquake.
The largest measured earthquake, so far, is the 1960 magnitude 9.5 Chilean earthquake, which occurred along a subduction zone. California's largest earthquake was the 1857 magnitude 7.9 Fort Tejon earthquake. While both of those quakes are very strong in their own rights, they are significantly smaller than a magnitude 10.5 earthquake. A magnitude 10.5 earthquake would release about 32 times more energy than a magnitude 9.5.
There are two types of tectonic plate boundaries along the West Coast of the U.S. and Canada. The San Andreas fault forms a plate boundary where the plates scrape along each other (a transform boundary) from the Imperial Valley in the south to Cape Mendocino in the north. North of Cape Mendocino, the oceanic plate is subducted or pushed under the continental plate along a plate boundary running parallel to and off the Northern California coast all the way to Aleutian Islands of Alaska. Although big earthquakes can occur along each of these plate boundaries, even if both of these boundaries ruptured at once – so unlikely as to almost be impossible -- it wouldn't be enough to produce a magnitude 10.5 earthquake.
Based on information gathered from the world's largest earthquakes, it would take a rupture 6,000 miles long along a subduction boundary to produce a magnitude 10.5 earthquake. That would be a rupture from the North Pole to the Equator, and that type and size boundary doesn't exist.
Though very large earthquakes can still occur in California – a fact that should not be ignored -- an earthquake of the magnitude presented in the miniseries is impossible. The potential for a magnitude 10.5 earthquake should be categorized as pure science fiction.
Will California fall off into the ocean during a huge earthquake? Where can I get beachfront property when it happens?
Before you go out and buy that land in the desert because it will someday be "beachfront property" (as Lex Luthor does in the 1978 "Superman: The Movie"), you should know that there is no chance of California falling off into the ocean and disappearing, or portions of it becoming an island all at once (as in the miniseries "10.5" or the movie “Escape from L.A.”).
In California, the San Andreas fault forms the boundary between two huge tectonic plates. The movement along the fault is sideways, or lateral, where the land on the west side is moving north relative to the land on the east. Because of this very slow lateral movement, which has a component of compression also, millions of years from now the cities of San Francisco and Los Angeles might be nearly adjacent to one another but neither will fall off into the ocean.
This is the biggest "urban legend" that has survived despite all the efforts of scientists to dispose of it. California falling into the ocean is strictly science fiction.
Can nuclear explosions cause or prevent earthquakes?
There is no evidence that a nuclear explosion could help cause or prevent earthquakes of a significant magnitude. The idea proposed in the miniseries "10.5," that nuclear explosions would "fuse" a fault or prevent it from rupturing, is wrong. You can't "spot weld" to hold a fault the size of the San Andreas.
Having said that, there is one instance where a 1968 nuclear test explosion caused a relatively small (less than a mile long) fault to rupture. However, seismographic records showed that the seismic waves produced by the fault movement were significantly smaller than those of the blast itself. There are also some records of very minor "aftershocks" occurring after a nuclear explosion. Still, the energy generated by a nuclear weapon and its effects on the subsurface are significantly smaller than what movies would have us believe.
In any case, the use of a nuclear explosion to cause or prevent a significant earthquake is considered science fiction.
Can the ground open up and/or close during an earthquake like they show in movies?
The ground typically doesn't open up and/or close like the movies so often show. In “10.5,” the ground "chases" and swallows a moving train, a city is swallowed up whole, and a car sinks into gravelly dirt. It’s not going to happen.
Earthquakes certainly can have ground-changing effects at the surface: rupture of the fault plane; liquefaction and lateral spread, where relatively flat ground can crack, flow, and turn into a kind of quicksand; and landslides and rock falls. Fault rupture and landslides typically don't open up holes in the ground. As a matter of fact, both usually result in the buildup of the dirt and rock. Of the three effects, liquefaction is the most likely to cause "holes" in the ground, but there are not many cases where liquefaction actually swallows up individual people. It typically causes most of its damage to structures that don't have an adequate foundation to resist settlement.
Overall, the science fact is that liquefaction opens holes in the ground but the perception in movies that the Earth opens up and swallows people is science fiction.
Does the San Andreas fault go through downtown Los Angeles as they show in the miniseries?
The San Andreas fault is located north of the San Gabriel Mountains on its closest approach to downtown Los Angeles, more than 30 miles northeast as the crow flies. This much is a fact, though: the San Andreas fault has been and will likely be the source for the largest earthquakes to affect the San Francisco Bay Area as well as portions of Southern California.
As you watch and enjoy “10.5,” keep the above facts (and fictions) in mind. Though an earthquake of such a "magnitude" is not realistic, all Californians need to be aware of and prepared for large earthquakes.
Though much of the "science" in the miniseries may seem right compared to what other movies have programmed us to think, reality is suspended much of the time. On a scale of 1 to 100, I'd have to give this movie a rating of only 10.5 on the reality scale. It seems appropriate to borrow a scene from “10.5” in which a mother utters to her daughter, scared after watching the news, “Honey, just forget about what you saw on TV.”
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