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What an earthquake sounds like

Posted: Mon Nov 05, 2007 9:25 pm
by Studio717
We had an earthquake in my area last week - a 5.6, which was the largest since the big Loma Prieta quake in 1989 (the World Series quake, if you remember that). Last week's was big enough to make you sit up and take notice and start thinking about where to duck. Fortunately, it ended right about then. :D

A reporter for the San Jose Mercury News was interviewing someone when the quake hit and recorded what it sounds like. There's a bit of talking at the beginning (before the quake), then the unmistakable sound of everything shaking. Since California earthquakes are legendary, I thought someone might be curious as to what they sound like when you're in the middle of one. (And be glad you're only listening... :) )

Sounds of an earthquake

(I only had a few books fall down, so nothing broken in my house.)

Posted: Thu Nov 08, 2007 5:01 am
by lenf
Laughing... I had moved to SF a few weeks before the 1989 quake, servant's quarters in one of the lovely Marina homes. I had just turned off Van Ness onto Chestnut when the quake hit. But I didn't hear or feel anything, being in a Jeep with rather stiff springs. I saw a bunch of bricks falling off the front of buildings, dust rising everywhere, and folks streaming out of buildings.

My home was a block away from the one that slid into the street, two blocks from the house that burned.

So, from my experience, a 6.1 sound is mostly silence.

Posted: Thu Nov 08, 2007 5:47 am
by xiamenese
I've been in earthquake 4 times in my life.

The first time was in Morocco, a couple of years after the devastating one at Agadir in 1961, I think it was. I was asleep, having just driven my father home to Rabat from Oujda on the Algerian frontier ... something over 500 miles in a single day. I woke up the next morning to find the whole neighbourhood camping on the waste land opposite our house. When I asked what was going on, I was told there had been an earthquake in the night! I knew nothing about it.

The other three times have been here in Xiamen, including the first night in my flat a couple of days after I first arrived. I woke up in the middle of the night and thought, "Hello ... this bed is shaking ... Oh, they must be having an earthquake in Taiwan (about 150 miles away across the Strait)." I checked when I got to work at the TV Station the next day. It had been quite a bad one in Taiwan, but no damage here.

The other two were on successive days about three years later. I went into the TV Station and said, "Have they been having earthquakes in Taiwan?" and my colleagues replied, "Earthquake? What earthquake?" Turned out I was right. I reckon I don't want to be in a big one, since I seem to pick up the slightest tremor now.

Mind you, the really terrifying thing is that there are serious plans still being mulled over, of linking mainland China and Taiwan by a combination of bridges and tunnels ... a bridge from Xiamen to Jinmen (Quemoy, under Taiwanese control) about 5 miles over the sea in a potential typhoon zone; tunnel from Jinmen to Penghu about 128 miles under deep ocean, through granite and in a major earthquake zone; then bridge from Penghu to Taiwan Island, about 30 miles over the sea in a combination of earthquake zone and potential typhoon zone. I say potential typhoon zone, because Taiwan Island is very mountainous and tends to deflect them north to north Fujian or Zhejiang Province or south to Guangdong Province and Hong Kong, so this part tends to be spared the worst. That said, there was a devastating typhoon here in Xiamen in 1999, though, about 10 months before I arrived.


Posted: Sun Nov 11, 2007 1:15 am
by ptram
I'm not sure how I can separate the sound I heard, and the sound I think I remember to have heard.

I've been in three major earthquakes in my life. The first time I was in the exact centre of the quake that damaged the nearby mountain villages. I don't remember any sound at all, apart for the screams of the people running out of the buildings as fast as possible. Vasco Rossi had just been introduced to the general audience at a music show on the state TV, so I guess there was something to do with his song. Maybe that was the sound of that earthquake.

The second time, the capitol of my region was hit, and I only remember the crystalline sound of my lamps shaking. My dog had started barking from some time, and it was impossible to make it shut up. The TV was suddenly turned on, and the news about the town's quarters sliding down the hill were shouting in the house.

The last time, I was up at night, and my desktop started to tremble, then to run away from my hands. I could clearly feel (if not hear) a low-level rumble in my body, my room, the village outside. While the quake lasted for more than a minute, my feeling lasted much less, since I was computing the following equation:

this is a safe zone : the two surrounding danger zones are several kilometers away = something big is happening there

The following day we could count 14 casualties, 20,000 homelesses, and several major monuments (including the basilica of Assisi) severely damaged. Then, came the sound of trucks transporting barracks at the disaster area over the mountains.


Posted: Sun Nov 11, 2007 2:02 am
by druid
Charles Darwin experienced a severe quake in Valdivia, Chile, in February, 1835. He reports that the sound depends on an observer's location: quiet in a forest, louder in a house, loudest of all in a city. The quake itself is not noisy, but its effect on structures and their contents produces the noise and terror.

"A bad earthquake at once destroys the oldest associations: the world, the very emblem of all that is solid, has moved beneath our feet like a crust over a fluid;—one second of time has conveyed to the mind a strange idea of insecurity, which hours of reflection would never have created. In the forest, as a breeze moved the trees, I only felt the earth tremble, but saw no consequences from it. Captain FitzRoy and the officers were at the town during the shock, and there the scene was more awful; for although the houses, from being built of wood, did not fall, yet they were so violently shaken that the boards creaked and rattled. The people rushed out of doors in the greatest alarm. I feel little doubt that it is these accompaniments which cause that horror of earthquakes, experienced by all those who have thus seen as well as felt their effects. Within the forest it was a deeply interesting, but by no means an awe-exciting phenomenon." ... ageseq=388

Posted: Sun Nov 11, 2007 5:11 am
by Studio717
The ones I've been through here in California usually make noise beginning with a sound that's similar to a train or a big truck. Then the shaking house noises start, but there's usually that first rumble before the clattering.

I'm not a scientist, or even close to one, but from a long-ago class in earthquakes, I remember learning that the composition of the ground you're on apparently matters a great deal and affects the amount and severity of damage. Also, the kind of faults matter - trenches like Alaska and Japan can have more severe earthquakes that the sliding faults like the ones here in California.

Here in California, they're slowly retrofitting older buildings and structures (like bridges) to be more earthquake resistent, but unlike for ptram, "old" here means mostly back to the mid-19th century. There are still a few adobes from the Spanish era, but that's it.

I hope I didn't bring up traumatic memories for people. The happenstance of recording something so fleeting made me think it was worth noting.

Posted: Tue Nov 13, 2007 2:04 pm
by Eldritch
Studio717 wrote:The happenstance of recording something so fleeting made me think it was worth noting.

And indeed it was. Thanks for that. Not really encountered, or heard, one before. Nearest being when i was young, and in primary school. That incident was so minor, it could have been mistaken for me passing wind. :shock:

Posted: Wed Nov 14, 2007 12:00 am
by gr
Is what one hears in an earthquake the quaking of the earth or rather the disturbance of everything shaken by it?

It is interesting to reflect that what you are hearing in an earthquake is probably mostly the amassed sounds of the disturbance and stressing of all of the things we have built there on the earth.

Just a thought.


P.S. After being in a substantial earthquake, your equilibrium system stops making its usual assumption about which is moving--you or your environment. So, when you turn or look or move, you have a momentary perception as though it might not be you moving, but the things around you. Unsettling in a low-level but peristent way. Lasts for months. (This observation courtesy of San Francisco, 1989.)