Life at the Epicenter: Preparing for the Mega-Quake

The Peeps were moving. It was Easter Day, 2010, and I was at a potluck brunch not far from downtown Los Angeles. It was characteristically sunny and warm, and many of the guests had settled into the host's backyard garden. I was one of a half-dozen people sitting at a wooden picnic table when the shaking began. At first I thought it might be nausea. I was four months pregnant and had already eaten one too many of the sugary marshmallow chicks. Then I saw that everything on the table was vibrating.

Earthquake.

Little about it was scary. In fact, the sensation was mildly pleasant, just a mellow undulation, like standing on a floating dock as a spent motorboat wake rolls through. In seconds, it was over.

Soon other guests filed out of the house. "Did you feel that?" people asked one another. A lot of them hadn't noticed a thing, but I was thrilled. After three years in L.A., it was my first true earthquake. Phones were fished from pockets and purses and Twitter feeds consulted. This was the real thing, a 7.2-magnitude tremor that originated in Mexico, 6 miles beneath the Baja Peninsula. There was some damage near the border, but Los Angeles had been spared. A few days later, my husband, Dan, and I were sitting in our living room when an aftershock hit. We briefly locked eyes, then turned our gaze to the darkened TV. We had recently bought our first flat-screen, and dutifully used $20 earthquake straps to secure it to the mantel above our defunct fireplace. They worked. The shaking stopped. Everything was fine.

The past few years have been turbulent ones for the planet. Earthquakes have caused massive devastation, killing 86,000 people in Pakistan in 2005; 87,000 in China in 2008; and close to 100,000 in Haiti in 2010. In the two highest-profile earthquakes of the past decade?the 2004 Sumatra quake and the 2011 Tohoku event in Japan?most of the death and destruction were caused by a subsequent tsunami, a rare geological phenomenon that to most Americans seemed as bizarre and otherworldly as an asteroid strike. Four of the 13 most deadly earthquakes in history have occurred since 2004?a statistic that says less about Earth than about how humans live on it. Growing populations and dense urban centers create greater hazards from natural disasters. (Even the strongest earthquake poses little danger to a person alone in a field.) When major quakes strike, as they inevitably will, people-packed cities like L.A. are most vulnerable.

Long before I moved to California I knew that earthquake-probability maps show the Pacific Coast traced in red, reflecting the major fault lines that form where tectonic plates abut. But until recently, I hadn't looked into the specifics: Seismologists estimate there's an 82 percent chance that a magnitude-7 or greater quake will hit directly beneath Southern California in the next 30 years. Three-quarters of all U.S. earthquake losses are expected to occur in the state, and experts' best-guess estimate is that damages will exceed $30 billion per decade on average.

Meanwhile, Americans have been reminded that earthquakes aren't purely a California hazard. In August 2011, a 5.8-magnitude tremor struck near Richmond, Va. That quake, felt from Georgia to Quebec, was the largest to hit the Southeast in more than a century. Using new paleoseismic data and more complex computer-forecasting techniques, the U.S. Geological Survey (USGS) is refining risk estimates for places such as the Cascadia subduction zone off the Pacific Northwest coast, the Wasatch fault near Salt Lake City, and the New Madrid seismic zone, extending from southern Illinois into Arkansas, which experienced four magnitude-7 quakes back in 1811 and 1812. Of course, probabilities tend to have less impact than personal memory of actual events, and throughout the U.S., it's been a time of relative quiet. The last earthquake to cause significant havoc was the 6.7-magnitude Northridge quake, which killed 57 people and delivered $20 billion in damage to the Los Angeles area in 1994. That mild Easter Sunday tremor in 2010 turns out to have been the most powerful earthquake to touch Southern California in nearly 20 years.

The same month, Dan and I were in the process of buying our first home. To us, the property was charming: a peak-roofed, light-filled house perched atop an ivy-smothered slope. We didn't mind the steep, uneven stairs that led to the front door, or the cracks in the flaking stucco and the concrete patio. For a house built in 1927, such scars seemed minor. We were pleased to learn that the building had been bolted?the foundation attached to the wooden frame with a series of struts and bolts. The job wasn't to code, but overall it looked pretty good, our home inspector told us. We reviewed insurance options. A basic policy would run us $550 a year. Add earthquake insurance and the cost more than doubled. We had a decent idea of worst-case scenarios: Friends had been "red-tagged" after Northridge, when authorities marked 1600 homes as uninhabitable and forbade residents to return. Still, what were the chances of that happening again? Of it happening to us? Looking more closely at the quote, I saw that the deductible for our home would be close to $50,000. Justifying the decision to forgo earthquake insurance wasn't difficult. The house has held up for this long, we rationalized. Something truly catastrophic would have to happen to make that expense worthwhile.

Still, Earthly hazards had seized my attention. In the past, I'd been exasperated by my East Coast family's concerned phone calls following news coverage of Southern California's forest fires. "That's nowhere near us! We're completely safe," I'd reassure them (though once we could see distant flames from our apartment's front porch). Now, though, I was the one worrying. The financial gamble of homeownership was part of it. The other was my son, Otto, who was born a few months after we moved into our new home. For the first time, I compiled a household earthquake kit, adding a week's worth of extra diapers, wipes, and baby food to the stockpile of water, flashlights, and first-aid supplies. I made room in the trunk of our hatchback for a basic survival kit including energy bars, a fire extinguisher, sneakers, more diapers, and a couple of 2-gallon water jugs, and studied the emergency-shutoff directions for our gas line and water heater. When the 9.0-magnitude earthquake, tsunami, and nuclear disaster struck Japan in March 2011, Dan and I half-jokingly debated the pros and cons of stocking up on plastic sheeting and duct tape. Nuclear disaster planners recommend a shelter-in-place approach to radiation plumes. But our house has neither a real basement nor any windowless rooms. Maybe sealing off our drafty, old-fashioned swing-open windows would help?

Did we think dangerous fallout from the Fukushima Daiichi power plant might actually stretch across the Pacific? (Some members of an online moms' group I lurked in were convinced it was already happening.) Or were we more concerned about a similar "unforeseen" disaster at the San Onofre nuclear power plant 60 miles to the south? (News that it had been built to withstand a magnitude-7 earthquake suddenly didn't sound so impressive.) I'm not really sure. Both of those possibilities seemed outrageously unlikely?yet it was foolish to completely dismiss them. What I knew to be true was that radiation exposure poses especially high risks for small children. Otto was 6 months old.

When I saw a flier advertising a free emergency-preparedness class at the local library, I signed up. Over seven evenings, I sat between an elderly Japanese couple and a row of aging hippie types as an L.A. firefighter schooled us on various disaster scenarios. We practiced triage and first aid with what struck me as a somewhat lofty idea that when the big one hit, all of us?informed, diligent citizens that we were?would be providing crucial backup to first responders. Gory videos of car crashes and building collapses were the backdrop to discussions on how to treat head trauma (the No. 1 earthquake injury, our instructor said); how to make or find potable water when utilities are cut off (mine your water heater); and the California laws governing defecating in your own yard (illegal! my live-free-or-die New Hampshire relatives would be outraged). But I also had a more fundamental question about earthquakes: What were the odds I'd ever have to use these skills?

In more than 30 years at the California Institute of Technology, seismologist Tom Heaton has developed a reputation as something of an earthquake maverick, with expertise in both geophysics and engineering. He's a large man, with suspenders that stretch over his neatly pressed dress shirt and a soft, jowly face framed by a cloud-like crown of white hair. I'm hoping Heaton will provide some straightforward facts to help me frame our mutual earthquake risk. Instead, he leans back, obviously bemused by a question he's heard too many times before. "It's almost like asking how big is the risk from wars, how big is the risk from epidemics," Heaton says. "When we look at the statistics of earthquake problems, they're the kind where things that don't happen very often end up being incredibly important."

Recent U.S. seismic history doesn't give us any real clues as to what lies ahead, Heaton says. "In the last century, we've only had deaths in the hundreds. But if you look at 1906, the largest city in the western U.S. was basically wiped out by an earthquake. Losing a major city would be hard for somebody to even imagine today. Maybe some people would say that it's impossible. But I don't think anybody actually knows that."

I ask Heaton what he thinks about my earthquake-insurance rationalization?that my house has endured 80 years of shaking, and so can probably hold up for the four or five more decades that Dan and I will be around. He smiles. "Oh no, that doesn't really tell you anything," he says. It's no accident that earthquake-probability forecasts use a 30-year time frame, the same as the typical home mortgage. Heaton has been intimately involved with the complex number-crunching responsible for those statistics, and while the figures undoubtedly help citizens evaluate risk?and engineers set building code standards?he is the first to admit that the forecasts are perplexingly vague. "I've fallen asleep a hundred times with those numbers," he says. "We argue and arm-wrestle. There's a million compromises." A magnitude-7 quake, after all, may be a neighborhood-flattening jolt or just another fun party story, depending on where and when it comes.

Heaton has raised three children in a Pasadena home built in 1910. He doesn't have earthquake insurance either. He used to, up until 1991, the year the 5.6-magnitude Sierra Madre earthquake damaged his home. "It broke some foundation; it destroyed the chimney," he says. "By the time it was done, it caused several tens of thousands of dollars in damage, and earthquake insurance paid for that. It was a good deal." Since then, the price of earthquake insurance has gone up, along with deductibles. Heaton and plenty of other Californians calculated that it made more sense to invest in upgrades that would protect against future quakes than to pay a skyrocketing monthly premium.

Though it's our homes we fret about most, they're usually the least vulnerable?at least single-family, wood-frame houses like the ones Heaton and I own. "Wooden houses are extremely resilient to earthquake shaking. It's almost unheard of that they actually collapse," he says. Far more dangerous are unreinforced brick structures and what engineers refer to as nonductile concrete buildings. Had the Northridge earthquake occurred during the workday rather than at 4:30 am, studies concluded, there would have been 20 to 30 times the fatalities. The same principle will likely apply when the inevitable big one strikes. A study that simulated a 7.9-magnitude rupture on the San Andreas fault (a repeat of the 1906 San Francisco quake) calculated that 8000 people would be seriously injured and 1800 killed if it occurred at night. If it struck during the day? Expect 12,500 injured and 3400 dead.

Earthquake Mechanics

Excessive pressure between tectonic plates can cause them to slip and the ground to rupture. A series of seismic waves emanate from this hypocenter (as opposed to the epicenter, the point directly above that on the surface). Fast-moving primary, or P-waves, reach seismograph stations first, and like lightning preceding thunder, can provide valuable seconds of warning before the real shaking begins. P-waves cause rock to expand and contract as they pass through it. Secondary shear, or S-waves, displace material at right angles to their path and reach the surface later. They undulate along Earth's crust much like ocean waves and, as a result, they cause the most damage.

Source: http://www.popularmechanics.com/science/environment/natural-disasters/life-at-the-epicenter-preparing-for-the-mega-quake-11644921?src=rss

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