As you sit at the dinner table, the pictures on the wall begin to rattle, and you hear a deep rumble in the distance. The ground beneath your feet begins to shake, and you see your home visibly trembling. It’s an earthquake!
Earthquakes are one of those natural phenomena that have captured the imaginations of geologists and filmmakers alike. They are depicted mildly as minor damage to roads and buildings, and as fantastically as gaping cracks opening in the earth’s crust to claim entire portions of a city. They present a very real danger to those within the vicinity, so it is good to receive a periodic refresher.
Without embarking on a deeply scientific explanation, recall that earthquakes tend to occur near the faultlines in the earth’s crust (tectonic plates), and the seismic magnitude is measured by a logarithmic scale generally from 0 to 9. In the U.S., the faultlines running throughout the West Coast are the most active, though earthquakes still occur in other parts of the country–Virginia sported 7 earthquakes in 2011 alone!
If you happen to live in Southern California, or elsewhere along the Pacific Rim, you have no doubt been exposed to an earthquake, and are well-versed in preparation and survival. For those who live in a less earthquake-prone area, or travel to tectonic hot-spots from time to time, read on for a basic primer in how to emerge alive.
Quick facts about Earthquakes
Geologists estimate that we experience over 50 quakes each day. The vast majority of these are minor (magnitude less than 5), and may not even be noticeable to some people. However, they also estimate roughly 15 annual quakes of magnitude 7, and 1 of magnitude 8. These are the city-destroyers that Hollywood portrays. The good news is that the fatality rate is uncharacteristically low in the United States: since 1990, fewer than three people were killed each year from earthquakes. (1994 was an outlier with 60 fatalities, due to the Northridge earthquake and its series of 6-magnitude aftershocks.)
Stay safe during an Earthquake
If you are outdoors or in a vehicle as an earthquake begins to rumble, your best bet is usually to get on solid ground away from bridges, tunnels, and buildings, and secure yourself (or set the vehicle in park). With the unlikely exception of a massive chasm opening under your feet, collapsing structures are your greatest danger.
In the more likely event you are indoors, your immediate actions should be to seek overhead cover and protect from falling objects. In more massive quakes, items such as a table or desk may even collapse under the weight of a heavy object, so some rescuers have described a “triangle of life” strategy: a heavy object comes to rest against a sturdy one that will not collapse, providing cover for those underneath (e.g. a falling tree will crush a desk, but not a concrete block).
After the initial shock (typically 10-30 seconds), you probably have a limited window to get to a more survivable position. Aftershocks are expected to follow from minutes to hours after the initial wave, so don’t allow yourself to get caught in a disadvantageous situation. If your structure is damaged, go find a better one. Ensure you can sustain a day or two in an isolated location—water, food, flashlights, whistles, telephone, and radio should be near the top of the preparation list.
Note that in coastal areas, tidal waves are a secondary effect of some quakes. They carry large masses of high-velocity water into areas that are not designed to withstand the force, and may leave residual floods for days or weeks after the fact. Distance and higher ground are your best defenses against this aquatic chaos—but beware of the dangers of being in a tall building facing a massive wave.
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So, next time you hear those pictures start to rattle on the wall, remember two things:
- Get to cover, quickly, and
- Hang those pictures with double-sided tape.