Today on Blogcritics

The Big One

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Californians — particularly those living in the southern half of that state — are living on borrowed time. Scientists have predicted with near certainty that the San Andreas Fault will produce an earthquake with a magnitude of at least 6.7 and likely higher than that.

Earthquakes, of course, are nothing new to Californians. Their state is riddled with fault lines, and minor earthquakes occur all the time. During the week of November 5 – November 12, the Southern California Earthquake Center (SCEC) recorded over four hundred minor earthquakes in California. Granted, only three of these registered above a 3.0 on the Richter scale, but the vast quantity of seismic activity cannot be ignored.

Earthquakes are a way of life in California, so much so that the population has learned to live with them. Buildings are designed to withstand a minimum level of earthquakes. Furniture is bolted to the walls of houses. Schools have earthquake drills. Fortunately, most earthquakes are so insignificant that people don’t even feel them. Every so often, though, a quake of serious magnitude hits, resulting in property damage, injury, and sometimes even loss of life.

In the past, four major earthquakes have been recorded in California due to the San Andreas Fault, which is the largest fault line in California. The first was the Fort Tejon earthquake in 1857, with an estimated magnitude of about 8.0. Only two deaths were reported. The second was the 1906 San Francisco earthquake, which registered a magnitude of 7.8. An estimated 3000 people were killed from the quake and subsequent fires. Next was the 1989 Loma Prieta earthquake, a 7.1 on the Richter. Sixty-three people died. Most recently, the 2004 Parkfield earthquake hit with a magnitude of 6.0, though no deaths or major injuries were reported.

Another one of these big ones is now looming on California’s horizon. For many years, scientists have tried to project what chance there was of an earthquake with a magnitude 6.7 or greater occurring in California in the next 30 years. In 1988, United States Geological Survey (USGS) believed that there was a 50 percent chance of such an earthquake. In 2003, that number increased to a 62 percent chance of a 6.7 or greater. A recent 2008 study by the USGS now places the 30-year chance of a large-magnitude earthquake at over 99 percent. An earthquake of this scale is described as “capable of causing extensive damage and loss of life.” The chances of an even more devastating 7.5 magnitude earthquake are thought to be 46 percent.

What is a Californian to do, considering these sobering numbers? One might think that they’d be leaving such a potentially dangerous area in droves, but the opposite is the case. California’s population is currently more than 38 million, up from just under 36 million in 2004 and about 34 million in 2000. Additionally, the state’s large population is concentrated in large metropolitan areas, several of which are seated firmly on known fault lines.

As counter-intuitive as it may seem, many California residents merely shrug, as though the high chances of a major quake were instead the numbers for whether or not it would rain the next day.

California resident Raymond Short said, “I would say most Californians, at least the ones I know, are pretty casual when it comes to earthquakes.”

That makes sense, at least to a certain extent. Building and safety codes are constantly being revised and improved upon as new data is collected from seismic activity. While there have been some serious earthquakes recently, relatively few people in recent memory have died from a quake, and even those few deaths were almost twenty years ago. Most of the earthquakes Californians have experienced recently were relatively benign — some torn-up roads here, a damaged building there, but nothing truly destructive.

“I live pretty much right over a fault line and I’m so used to the average earthquake that I’m excited when we get one,” Mr. Short continued. “Once in a while we will bring up that we’re overdue for a big quake, but we definitely don’t stress about that. Sometimes I hear about a moderate earthquake from the news or a friend and I didn’t even notice.”

Despite the levity with which Short discussed earthquakes, he still takes precautions in the event that something truly dangerous does occur. Everything in his house is bolted down, for starters. In the event of an earthquake, this helps in two ways: first, the chances of something breaking are greatly reduced. Second, the chances of a heavy piece of furniture falling and injuring someone are also significantly smaller. Additionally, Short said that his house had been designed to not only meet earthquake safety codes, but to exceed them by a significant margin.

During an earthquake, the best safety measure to follow is something known as “Drop, Cover, and Hold On.” This principle reduces the chance of injury or death during an earthquake. First of all, drop to the ground. This minimizes the area of space you’re taking up, thereby reducing the chance that you’ll be hit by debris or shrapnel. Next, cover your head, either with your arms or by moving under a table. The more protection you’ve got around your head, the less likely you are to sustain a potentially dangerous injury. Finally, hold on to furniture (even if it is moving). This gives you added stability and provides protection in the form of the so-called “triangle of life,” formed when (theoretical) falling debris impacts the furniture instead of your body and forms a right triangle with the furniture and the floor.

All of these techniques can reduce the risk of injury or death, but there is no foolproof method for surviving a major earthquake. Ironically, it isn’t in the quake itself that most deaths occur, but in the fires that can result from ruptured gas lines.

“We definitely take preventative measures, but even then something is likely to break during the bigger quakes,” Mr. Short said. “I’ve been in some decent-size earthquakes in California, ones that give you a rush of adrenaline. Those make you think about how bad a huge one would be.”

No kidding.

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