What An Earthquake Feels Like

What an earthquake feels like to you depends on its size and intensity, your location, and your local geology and architecture.

As a former longtime resident of California and Japan (a decade each), I have experienced a number of earthquakes, large and small. No two are alike, and you never know when one is going to turn out to be "The Big One."

The surface of planet Earth is covered by thin, stiff "tectonic plates," which can be quite large, even covering an entire ocean floor. The meeting points of these plates are called "faults" and the there the plates grind together, sometimes at a slow but steady pace and sometimes sporadically. This grinding causes energy to be released, either steadily or after a build-up. What you feel in earthquake depends on a whole slew of factors, not least of which are whether the energy was released more or less steadily (you will feel a little jolt) or after a build-up (this is likely to be more serious); how far you are from the epicenter (where the quake originates), magnitude (how much energy has been released); intensity (how much shaking goes on), the geology of the affected area (buildings sitting on soft earth are going to suffer more damage than those built on rock) and the architecture of the area (there is a science to building earthquake-proof buildings, bridges, highways and even parking lots).

There are also three major earthquake types: vertical plate motion at the epicenter, horizontal motion at a farther location, and both motions at once, also far from the epicenter and these types feel quite different from one another.

Vertical plate motion at the epicenter causes a single, intense shock: I've experienced this as BOOM, both motion and noise, but with no significant duration; it's all over in an instant. You may think your house has been hit by a train, except that not only is there no train in your house, but the train seems to have hit all four of your walls at once.

Horizontal motion far from the epicenter is a different earthquake experience altogether: it can still be mild, but it has duration; it may last only a few seconds but you feel them as a continuous event. At first there is a gentle quivering of the ground or floor, and that might be the end of it... or it might escalate into a violent, rapid jerks, rolls and waves. (All of this depends great deal on where the quake has originated, though what kind of rock and earth its waves have traveled, and how much energy it being released by this action.)

The third type of quake is a mixed bag and you never know quite what you're going to get!

The closer you are to the epicenter, the faster and more violent your quake experience will be. "P" waves travel fast in all directions from the epicenter and they compress and expand everything in their path; they make the BOOM. "S" waves are slower and make everything perpendicular to them ripple and shake.

There are several scales used in the measurement of quake magnitude and intensity. Magnitude is how big the quake is and intensity is how much everything shakes.

The most commonly used scale for magnitude is the Richter Scale; among those that measure intensity are the Mercalli and the Rossi-Forel. Magnitude and intensity are both experienced differently according to your distance from the epicenter, but the numbers eventually given to the quake refer to the epicenter itself.

If you're in the middle of an earthquake, you are likely to have your own intensity scale, ranging from "gee, that didn't impress me much" to "holy cow, get me OUT of here!" Most of the quakes I've felt were gentler than otherwise, ranging from the "was that an earthquake or was someone moving furniture on the floor above us?" (we were on the top floor of a small office building in Los Angeles; there was no one above us) to the "R., leave my chair alone!" (R., my five-year-old niece, was across the room and not shaking her mother's chair after all; we were in a cafe on perhaps the fifth or sixth floor of a department store in Tokyo). The latter was my sister's first (and perhaps only) earthquake, and she was surprised by both its gentleness and its definite presence. While there was no destruction involved, she was absolutely convinced that her young daughter had grabbed a hold of her chair and was vigorously shaking it.

On January 17, 1994, I was at home in Nagoya, Japan, talking on the phone with M. in Los Angeles, when suddenly I heard crashing sounds through the phone and M. began to repeat, "Oh my God!" We were quickly disconnected and when I called back I was obstructed by a persistent busy signal. I called E., also in Los Angeles, he answered the phone "YOU CAN'T CALL ME NOW!" He meant of course that my timing was bad; Los Angeles was experiencing the Northridge Earthquake, both BOOM and jerk, 6.1 on the Richter Scale.

M.'s major memory is of breaking glass: the sound of her possession shattering, and the horror of their shards all over her apartment.

E. reacted quickly by gathering his three dogs and running out into the street, to find the whole neighborhood congregated there. There was no light except where structures had caught fire. A head count revealed that one of their elderly neighbors was unaccounted for; my friend knocked on her door, then ran around to the back and, peering in through the window, saw her pinned down under her couch. He used his shoulder to crash through the back door and pull her out to safety; he didn't realize until much later he'd injured his shoulder. To him, an earthquake felt like a call to action. To the elderly neighbor, a Holocaust survivor, it felt like the end of the world. She was one of over nine thousand people injured in that quake; fifty-one people were killed and 22 thousand left homeless -- all in 15 seconds!

Precisely a year later, I was lying in my bed in Nagoya, still awake at the ridiculous hour of six in the morning, when my bed began to vibrate very slightly. I was tired and didn't want to get out of bed and stand in a doorway. "It's just an earthquake," I grumbled, closing my eyes. "It'll go away." It didn't go away. It increased in intensity... and kept increasing. Even the longest earthquake I'd ever felt had only lasted a few seconds, albeit each second could be perceived as a small eternity. This one just wasn't stopping. Two of my three cats fled the room in terror (one slept through the whole thing). I got out of bed and stood in the doorway between my bedroom and the bathroom, one hand on a wall and the other on the side of the built-in wardrobe. To my amazement, the wall buckled under my hand as if it were made of rubber. And STILL the quake kept going, and kept growing! The floor never caved; I was never in any danger of falling. Nothing fell off of shelves. (The BOOM sort often impels household goods to go flying and crashing.) Then the intensity began to lessen until all shaking and buckling had stopped. It was over, after what I was certain had been a minute or more. (In fact it had lasted 20 seconds at the epicenter -- but the farther from the epicenter you are, the longer you feel the effects, so my perception may well have been correct for my location. At any rate, even 20 seconds, in earthquake terms, is no small eternity but a huge one!)

It wasn't long before I learned that my experience had been extremely mild in light of what had actually happened: this was the Great Hanshin Earthquake, also known as the Kobe earthquake, 7.2 on the Richter Scale, its epicenter a mere 90 miles from my home, almost six thousand people had lost their lives, with almost 27 thousand more injured, buildings had crumbled to dust; the Hanshin Expressway was all rubble and corpses. To me it had been an annoyance. To western Honshu, as to the Holocaust survivor in Los Angeles a year earlier, it had felt like the end of the world -- and for thousands it was.

B., on the other hand, was in an earthquake in Locarno, Switzerland, in the spring of 1975, and remembers "it just shook around a little. We went downstairs and everyone spoke Italian except us so we couldn't really talk about it."

L. was only six years old in 1965 when "the kitchen table started shaking, sending my Cheerios everywhere (I had been making designs). I was scared. Mom and Grandma grabbed me and we went down into the cellar. The ground shook and shook. Some pictures fell off the wall. After it stopped, we went upstairs and cleaned up." What they were cleaning up were the results of the

April 29, 1965 Seattle-Tacoma Puget Sound earthquake, bigger than the Northridge (about 6.25 on the Richter Scale) and yet claiming only two casualties. Size doesn't necessarily matter!

I no longer live in earthquake country; I've dodged baseball-sized hailstones and watched tornadoes pass me by. I miss the occasional rumble and rattle of old. If you live your entire life earthquake-free, count yourself lucky and unlucky at once: you have escaped injury, economic loss and maybe even death, but you've also missed one heck of a roller coaster ride.

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