Quaking in California

Articles about the “big one” short on science

The 9.0 earthquake that struck Japan on March 11 not only sent a tsunami barreling across the Pacific, but also waves of concern about natural disaster preparedness and nuclear safety elsewhere.

In United States, the media have paid particularly close attention to California, home to two nuclear power plants and the country’s most damaging temblors, and second only to Alaska in total number of quakes. The question on every reporter’s mind: could the same devastation meted out in Japan also befall the Golden State? Dozens of articles have tried to answer that question, but the information they have provided about the latest developments in earthquake science has been less than comprehensive.

Two headlines in particular had commentators scratching their heads (emphasis added):

• “Special report: Big California quake likely to devastate state” (Reuters, March 14)
• “Japan-style earthquake and tsunami unlikely to hit Southern California, experts say” (Los Angeles Times, March 14)

Which is it? Good question. The first article, by Peter Henderson, starts by painting a portrait of a dystopian, earthquake-ravaged future that is clearly meant to startle readers into paying attention:

California will experience unthinkable damage when the next powerful quake strikes, probably within 30 years, even though the state prides itself on being on the leading edge of earthquake science.

Modern skyscrapers built to the state’s now-rigorous building codes might ride out the big jolt that experts say is all but inevitable, but the surviving buildings will tower over a carpet of rubble from older structures that have collapsed.

Hot desert winds could fan fires that quakes inevitably cause, overwhelming fire departments, even as ancient water pipelines burst, engineers and architects say.

Part of the lesson from the disaster that hit Japan on Friday is that no amount of preparation can fully protect a region such as California that sits on top of fault lines.

Henderson’s introduction relies heavily on scare tactics and is, in some respects, overwrought. The future he sketches is based on a 2008 report from the United States Geological Survey (USGS), which the article goes on to quote saying, “The question is not if, but when Southern California will be hit by a major earthquake - one so damaging that it will permanently change the lives and livelihoods in the region.”

Titled “The ShakeOut Scenario,” the report describes the consequences of a hypothetical 7.8 earthquake on the southern San Andreas fault, which causes widespread destruction. It’s a grisly read, to be sure, but when Henderson reported that the analysis “predicted 2,000 deaths and $200 billion damage,” he failed to mention that that’s only “if we take no additional actions for preparedness and mitigation.” His article also didn’t explain that while the USGS emphasizes that its scenario (based on geologic, seismic, and socio-economic data and modeling) is “realistic,” and should be used for planning and preparedness purposes, it is not prediction.

“The next earthquake will be different in details for the ShakeOut earthquake, and its total damages and losses will differ, because each earthquake produces its own patters of shaking and damages,” the report said. “However, the widespread, regional effects will be similar, and so will the long-term social and economic impacts.”

Indeed, while Reuters risked pandering to readers, and news reporters should not emulate the purple prose of its lede, its article may have been closer to the mark the one from the Los Angeles Times, whose headline read, “Japan-style earthquake and tsunami unlikely to hit Southern California, experts say.”

The problem with the Times’s piece is the adjective “Japanese-style.” The article quotes an earthquake expert making the important observation that unlike Japan, where tectonic plates are converging, there is no subduction where plates meet in California. Instead, they slide past one another along a transform fault, and while the horizontal slip can create tsunamis, they are generally not as large as those created by thrust faults in subduction zones, which involve vertical slip and thus greater displacement of water (the article did mention that there is a subduction zone in the Pacific Northwest; an article produced by the U.S. National Science Foundation for U.S. News & World Report said the risks there are “nearly identical” to those in Japan). Another expert quoted in the article estimates that faults in Southern California could generate temblors of magnitude up to 7 to 7.5, well short of the 9.0 mega-quake that shook Japan. So, no, perhaps a “Japanese-style” quake and tsunami are not in the offing, but that statement belies the fact a “California-style” quake could cause plenty of destruction nonetheless.

Another article from Reuters, by Steve Gorman, took a similar tack as the Los Angeles Times, pointing out that the next “big one” in California is “expected to pale next to the Japan quake.” It explained that subduction zones create the world’s most powerful earthquakes and “a 9.0 quake is virtually impossible along the San Andreas” network of strike-slip faults. Unlike the Times, however, it quoted a USGS spokesperson emphasizing that “you don’t need a magnitude 9 to cause extensive damage,” though it was careful to mention that part of the reason for that is that California’s buildings are not as earthquake resistant as those in Japan.

A great piece from the Associated Press had more detail about the Golden State’s feeble infrastructure, pointing out, among other things, that “California’s five-year-old program for helping cash-strapped public schools seismically retrofit their most vulnerable buildings has so far disbursed only a tiny portion of the $200 million set aside under the effort. The San Francisco-Oakland Bay Bridge, damaged in the 1989 earthquake, still hasn’t been replaced. Thousands of old hospitals and apartment buildings remain despite being at serious risk in a quake.” (The San Diego Union Tribune published a letter from a member of the Structural Engineers Association of California calling on government to work more closely with the group to ensure public safety.)

Henderson’s article for Reuters cited a second 2008 report from the USGS, which concluded that there is 99 percent probability that California will experience one or more magnitude 6.7 or greater quakes in the next thirty years, and a 46 percent chance that it will experience one or more magnitude 7.5 or greater quakes in that time. The report also concluded that about three magnitude 5 or greater quakes will occur in the state per year, and that a magnitude 6 or greater quake will happen about every one-and-a-half years.

Gorman’s article for Reuters reported that a major California earthquake is “long overdue,” although it did not elaborate or provide any supporting evidence. For such detail, one would have to turn to MSNBC.com, which quoted an earthquake expert at the University of California at Davis, John Rundle, explaining that historical analyses show that there is a major temblor along the San Andreas about every 160 years and that the last one was in 1857, 154 years ago. Along the Cascadia subduction zone, which stretches from Vancouver Island to Northern California in the Pacific Northwest (and features the Juan de Fuca plate sliding under the North American plate), there is a major event every about 500 years and the last one was in 1700, 311 years ago (an AFP article, however, quotes a geotechnical engineer at the Oregon Department of Geology who says the fault ruptures more like every 240 years).

The main thrust of MSNBC.com’s article is actually whether or not earthquakes happen in clusters, given the recent temblors in Japan, New Zealand, and Chile. A number of experts weigh in on the matter. The article jumps off from a column in Newsweek by Simon Winchester, the author of Krakatoa and books about geologic history, who argues that there is “little doubt” that earthquakes happen in clusters (the outlet also interviewed Winchester). Then it paraphrases Rundle, the earthquake expert from UC Davis, saying that while scientists have tended to view major earthquakes as impendent, and clustering as random, the recent string of forceful temblors worldwide has some asking about correlation. Then it quotes a geophysicist with the USGS saying, “There is no evidence of global large-earthquake clustering beyond localized aftershock sequences.”

The yes-maybe-definitely-not quotation strategy might leave the impression of he-said-she-said reporting, but the takeaway message from MSNBC.com’s work is that there is, in fact, plenty of doubt surrounding Winchester’s theory that earthquakes cluster. An article in The Boston Globe also does a good job explaining that while they “might seem like a powerful trend … geophysicists do not know whether the clustering of large earthquakes represents anything more than chance.”

Most of the articles cited above also mentioned that it is still impossible to predict earthquakes. What none of them provided, however, was a clear description of the research geologists and seismologists are are doing to improve their knowledge. A piece from Popular Mechanics stood apart in this regard, explaining that:

Despite decades of research, seismologists are still unable to predict these catastrophic events. Some experts fear they may be chaotic phenomena and hence fundamentally unpredictable. Instead, scientists focus on more attainable goals, deploying sensor arrays, satellite instrumentation and computer simulations to develop a clearer picture of how earthquakes happen, where they are likely to strike and how much damage they can do.

The article then goes on to describe a project called the San Andreas Fault Observatory at Depth, a sister program called the Plate Boundary Observatory, and finally, the Large High Performance Outdoor Shake Table at the University of California at San Diego, each of which is providing new information about earthquake dynamics. In a similar fashion, Nature News distanced itself from the pack with an article explaining why “few experts thought the seismic zone off Sendai, Japan, was capable of such violence.” The piece focuses on what the event is teaching scientists about the relative earthquake potential related to subduction of old, versus new, oceanic crust.

These detailed accounts of ongoing earthquake research should guide more reporters. Articles about the statistical likelihood of earthquakes in California and how those quakes might compare to the one in Japan are fine, but readers would surely benefit from more specifics about how scientists know what they know and about how the Golden State is using that knowledge (or not) to safeguard the public.

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Curtis Brainard writes on science and environment reporting. Follow him on Twitter @cbrainard. Tags: , , , , ,