Quake myths rely on cloudy facts

Nancy Huang and her son, James, were driving on state Route 56 toward their Carmel Valley home on March 31 when they noticed some striking cloud patterns set aglow by the setting sun. They snapped a few photos.

“I told James they looked like earthquake clouds,” said Huang, who remembered reports of such clouds appearing just before a major temblor in Sichuan, China, in 2008. “We talked about being prepared for a quake. We made a bet about what might happen next.”

Virtually everybody in San Diego County, if not Southern California, knows what happened next.

Four days after the Huangs’ cloud sighting, a series of quakes struck south of Mexicali, about 110 miles east of San Diego. The largest measured 7.2 in magnitude.

Hundreds of aftershocks followed and continue to occur. Seven have reached magnitude 5 or greater, including a 5.3 quake yesterday at 9:44 a.m.

So, did Huang and her son see earthquake clouds?

The short answer, at least based on credible scientific research, is no. Still, the idea of earthquake clouds and other quake myths persist.

The cloud concept is promulgated by people such as Zhonghao Shou, a retired Chinese chemist living in Seattle. He explains the phenomenon this way: Accumulating stresses in an earthquake fault produce fissures and cracks in rock, which allows water to collect. As pressures accumulate, the water heats, vaporizes and rises to the surface, where it escapes into the atmosphere to form unusual cloud patterns.

These clouds can appear — and disappear — hours, days, even months before an earthquake occurs, Zhou said. He claims he has made more than 50 quake predictions by discerning certain cloud patterns from satellite images, with a 68 percent accuracy rate.

Most seismologists are skeptical.

“No statistical correlation between earthquakes and meteorology has ever been demonstrated,” said Greg Lyzenga, a physicist at Harvey Mudd College in Claremont. “And if it were, it would take some mighty strenuous theoretical gymnastics to figure out a plausible cause-and-effect relation.”

Here are four other false, dubious or overhyped ideas regularly unearthed after a big quake:

Myth 1: Earthquakes always happen in the morning, usually when it’s hot and dry.

Earthquake weather is perhaps the most common misconception, said John Ebel, a geophysicist at Boston College.

“There’s a human tendency to try to explain phenomena like earthquakes based on things we’re familiar with. People pay great attention to the weather because it affects daily lives. They’re very familiar with changes in the weather,” he said.

So when a quake happens, Ebel said, people automatically associate the sudden shaking with something they think they’ve been paying attention to.

Quakes actually take place at all hours, in diverse places with different climates. The 7.2 temblor last Sunday occurred at 3:40 p.m. under partly sunny skies.

Myth 2: Animals sense earthquakes coming and behave strangely.

It’s true that some animals possess sensory abilities beyond those of humans, said Rulon Clark, an assistant professor of biology at San Diego State University.

Bats and whales hear sounds at frequencies higher or lower than people. Birds detect light and colors invisible to human beings. Rodents, snakes and other creatures that spend their lives close to the ground — or under it — are naturally more sensitive to vibrations, which may be clues to nearby food or predators.

“It’s possible that some of these animals can detect (earthquake) waves arriving seconds, maybe a minute, before the real shaking,” Clark said.

But the supporting evidence is almost entirely anecdotal. And like the weather, Clark said, people tend to remember things that support their beliefs and forget the conflicting evidence.

Myth 3: Lots of little quakes will help prevent a big one from striking.

Don’t kid yourself: The Big One will happen. It’s just that scientists can’t say with certainty whether it will happen tomorrow or 50 years from now.

Small quakes — those in the range of magnitude 2 to 4 — are not strong enough to significantly relieve tectonic stresses for long periods.

California experiences dozens, often hundreds, of quakes each day. Most are too weak to be felt, and it would take a lot of them to equal even one medium-sized temblor. Each whole-number rise in magnitude represents about 30 times more energy released.

A small quake might relieve some local pressure, but it might also shift that pressure to another part of the fault zone.

Myth 4: When the Big One occurs, California will fall into the ocean.

This is a Hollywood favorite, most recently seen in last year’s disaster epic “2012,” where large chunks of upended California coastline slid into the blue Pacific.

But the ocean isn’t a big hole of water with the state teetering on its edge, just waiting for a good jolt to send everything west of Arizona plummeting to a splashy doom, said Erin Beutel, a professor of geology at the College of Charleston in South Carolina.

She describes California as sitting atop a continental plate bumping and grinding against the somewhat lower, larger, water-covered Pacific plate. Both plates are floating on a deeper sea of molten rock, bobbing and banging against each other like boats lashed together.

“In this analogy,” Beutel said, “California can’t ‘fall’ anywhere.”

Except for a good myth.