Quantcast
Climate
Collapsed Santa Monica Freeway bridge across La Cienega Boulevard, Los Angeles after the Northridge earthquake, Jan. 17, 1994. Robert A. Eplett / FEMA

California’s Other Drought: A Major Earthquake Is Overdue

By Richard Aster

California earthquakes are a geologic inevitability. The state straddles the North American and Pacific tectonic plates and is crisscrossed by the San Andreas and other active fault systems. The magnitude 7.9 earthquake that struck off Alaska's Kodiak Island on Jan. 23, was just the latest reminder of major seismic activity along the Pacific Rim.


Tragic quakes that occurred in 2017 near the Iran-Iraq border and in central Mexico, with magnitudes of 7.3 and 7.1, respectively, are well within the range of earthquake sizes that have a high likelihood of occurring in highly populated parts of California during the next few decades.

The earthquake situation in California is actually more dire than people who aren't seismologists like myself may realize. Although many Californians can recount experiencing an earthquake, most have never personally experienced a strong one. For major events, with magnitudes of 7 or greater, California is actually in an earthquake drought. Multiple segments of the expansive San Andreas Fault system are now sufficiently stressed to produce large and damaging events.

The good news is that earthquake readiness is part of the state's culture, and earthquake science is advancing—including much improved simulations of large quake effects and development of an early warning system for the Pacific coast.

The Last Big One

California occupies a central place in the history of seismology. The April 18, 1906 San Francisco earthquake (magnitude 7.8) was pivotal to both earthquake hazard awareness and the development of earthquake science—including the fundamental insight that earthquakes arise from faults that abruptly rupture and slip. The San Andreas Fault slipped by as much as 20 feet (six meters) in this earthquake.

Although ground-shaking damage was severe in many places along the nearly 310-mile (500-kilometer) fault rupture, much of San Francisco was actually destroyed by the subsequent fire, due to the large number of ignition points and a breakdown in emergency services. That scenario continues to haunt earthquake response planners. Consider what might happen if a major earthquake were to strike Los Angeles during fire season.

Seismic Science

When a major earthquake occurs anywhere on the planet, modern global seismographic networks and rapid response protocols now enable scientists, emergency responders and the public to assess it quickly—typically, within tens of minutes or less—including location, magnitude, ground motion and estimated casualties and property losses. And by studying the buildup of stresses along mapped faults, past earthquake history, and other data and modeling, we can forecast likelihoods and magnitudes of earthquakes over long time periods in California and elsewhere.

However, the interplay of stresses and faults in the Earth is dauntingly chaotic. And even with continuing advances in basic research and ever-improving data, laboratory and theoretical studies, there are no known reliable and universal precursory phenomena to suggest that the time, location and size of individual large earthquakes can be predicted.

Major earthquakes thus typically occur with no immediate warning whatsoever, and mitigating risks requires sustained readiness and resource commitments. This can pose serious challenges, since cities and nations may thrive for many decades or longer without experiencing major earthquakes.

California's Earthquake Drought

The 1906 San Francisco earthquake was the last quake greater than magnitude 7 to occur on the San Andreas Fault system. The inexorable motions of plate tectonics mean that every year, strands of the fault system accumulate stresses that correspond to a seismic slip of millimeters to centimeters. Eventually, these stresses will be released suddenly in earthquakes.

But the central-southern stretch of the San Andreas Fault has not slipped since 1857, and the southernmost segment may not have ruptured since 1680. The highly urbanized Hayward Fault in the East Bay region has not generated a major earthquake since 1868.

Reflecting this deficit, the Uniform California Earthquake Rupture Forecast estimates that there is a 93 percent probability of a 7.0 or larger earthquake occurring in the Golden State region by 2045, with the highest probabilities occurring along the San Andreas Fault system.

USGS

Above: Perspective view of California's major faults, showing forecast probabilities estimated by the third Uniform California Earthquake Rupture Forecast. The color bar shows the estimated percent likelihood of a magnitude 6.7 or larger earthquake during the next 30 years, as of 2014. Note that nearly the entire San Andreas Fault system is red on the likelihood scale due to the deficit of large earthquakes during and prior to the past century.

Can California Do More?

California's population has grown more than 20-fold since the 1906 earthquake and currently is close to 40 million. Many residents and all state emergency managers are widely engaged in earthquake readiness and planning. These preparations are among the most advanced in the world.

For the general public, preparations include participating in drills like the Great California Shakeout, held annually since 2008, and preparing for earthquakes and other natural hazards with home and car disaster kits and a family disaster plan.

No California earthquake since the 1933 Long Beach event (6.4) has killed more than 100 people. Quakes in 1971 (San Fernando, 6.7); 1989 (Loma Prieta; 6.9); 1994 (Northridge; 6.7); and 2014 (South Napa; 6.0) each caused more than US$1 billion in property damage, but fatalities in each event were, remarkably, dozens or less. Strong and proactive implementation of seismically informed building codes and other preparations and emergency planning in California saved scores of lives in these medium-sized earthquakes. Any of them could have been disastrous in less-prepared nations.

Nonetheless, California's infrastructure, response planning and general preparedness will doubtlessly be tested when the inevitable and long-delayed "big ones" occur along the San Andreas Fault system. Ultimate damage and casualty levels are hard to project, and hinge on the severity of associated hazards such as landslides and fires.

Several nations and regions now have or are developing earthquake early warning systems, which use early detected ground motion near a quake's origin to alert more distant populations before strong seismic shaking arrives. This permits rapid responses that can reduce infrastructure damage. Such systems provide warning times of up to tens of seconds in the most favorable circumstances, but the notice will likely be shorter than this for many California earthquakes.

Early warning systems are operational now in Japan, Taiwan, Mexico and Romania. Systems in California and the Pacific Northwest are presently under development with early versions in operation. Earthquake early warning is by no means a panacea for saving lives and property, but it represents a significant step toward improving earthquake safety and awareness along the West Coast.

Managing earthquake risk requires a resilient system of social awareness, education and communications, coupled with effective short- and long-term responses and implemented within an optimally safe built environment. As California prepares for large earthquakes after a hiatus of more than a century, the clock is ticking.

Reposted with permission from our media associate The Conversation.

Show Comments ()

EcoWatch Daily Newsletter

Sponsored
Popular
Michigan Department of Health and Human Services Director Nick Lyon, seen here speaking to the press about the Flint water crisis in 2016, will be the highest ranking official to stand trial over the public health disaster. Brett Carlsen / Getty Images

Judge Orders Michigan Health Director to Face Trial Over Flint Water Crisis Deaths

Michigan Department of Health and Human Services Director Nick Lyon will be the highest ranking official to go to trial so far as a result of an investigation into the Flint water crisis, The Associated Press reported Monday.

Judge David Goggins ruled Monday there was probable cause for Lyon to stand trial for involuntary manslaughter in the deaths of Robert Skidmore and John Snyder that prosecutors say were due to a Legionnaires' disease outbreak that Lyon was aware of a year before he alerted Michigan's governor, Michigan Live reported. Lyons is also charged with misconduct in office.

Keep reading... Show less
Politics
Coal-fired power plant near Becker, Minnesota. Tony Webster / Flickr / CC BY-SA 2.0

Trump's 'Dirty Power Plan' Could Cost More Than 1,000 Lives a Year

The U.S. Environmental Protection Agency (EPA) unveiled on Tuesday its long-anticipated replacement of the Obama-era Clean Power Plan. The new coal pollution rules will increase planet-warming carbon pollution and could cost more than a thousand American lives each year, according to the EPA's own estimates.

EPA Acting Administrator Andrew Wheeler released the "Affordable Clean Energy Rule" today under President Trump's directive. The new plan encourages efficiency improvements at existing coal plants to ensure they operate longer and allows states to weaken, or even eliminate, coal emissions standards. That's a clear difference from former President Obama's plan, which was aimed at phasing out coal and transitioning to cleaner power sources to avoid dangerous climate change.

Keep reading... Show less
Health
Two workers in protective gear scrape asbestos tile and mastic from a facility at Naval Base Point Loma in California. NAVFAC / Flickr / CC BY 2.0

Why Asbestos Is Still a Major Public Health Threat in the U.S.

Reports surfaced this month that the U.S. Environmental Protection Agency (EPA) had proposed a significant new use rule (SNUR) for asbestos in June, requiring anyone who wanted to start or resume importing or manufacturing the carcinogenic mineral to first receive EPA approval.

Keep reading... Show less
Animals
Rklfoto / Getty Images

Bipartisan Group of Lawmakers Wants to End EPA’s Cruel Animal Testing

By Justin Goodman and Nathan Herschler

A bipartisan group of lawmakers in Congress recently pressed the U.S. Environmental Protection Agency (EPA) on its "questionable" and "dubious" animal tests. The lawmakers' demand for information on "horrific and inhumane" animal testing at the EPA comes on the heels of a recent Johns Hopkins University study that found that high-tech computer models are more effective than animal tests.

Keep reading... Show less
Sponsored
Climate
Wikimedia Commons

Strongest, Oldest Arctic Sea Ice Breaks Up for First Time on Record

The Arctic is warming at a rate twice as fast as the rest of the globe, and now the region's thickest and oldest sea ice—also known as "the last ice area"—is breaking up for the first time on record, the Guardian reported Tuesday.

The breakage has opened up waters north of Greenland that are normally frozen-solid even in the peak of summer.

Keep reading... Show less
Energy
Climate Justice Edmonton

These Giant Portraits Will Stand in the Path of Trans Mountain Pipeline

By Andrea Germanos

To put forth a "hopeful vision for the future" that includes bold climate action, a new installation project is to be erected along the controversial Trans Mountain pipeline expansion route to harnesses art's ability to be a force for social change and highlight the fossil fuel project's increased threats to indigenous rights and a safe climate.

Keep reading... Show less
Sponsored
Popular
A worker inspects recycled plastic in a plastics factory. Getty Images

The Plastic Waste Crisis Is an Opportunity to Get Serious About Recycling

By Kate O'Neill

A global plastic waste crisis is building, with major implications for health and the environment. Under its so-called "National Sword" policy, China has sharply reduced imports of foreign scrap materials. As a result, piles of plastic waste are building up in ports and recycling facilities across the U.S.

Keep reading... Show less
Adventure
Aaron Teasdale

The One Thing Better Than Summer Skiing

By Aaron Teasdale

"There's snow up here, I promise," I assure my son Jonah, as we grunt up a south-facing mountainside in Glacier National Park in July. A mountain goat cocks its head as if to say, "What kind of crazy people hike up bare mountains in ski boots?" He's not the only one to wonder what in the name of Bode Miller we're doing up here with ski gear.

Keep reading... Show less
Sponsored

mail-copy

The best of EcoWatch, right in your inbox. Sign up for our email newsletter!