How long do structures continue shaking after quake?

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Discussion Overview

The discussion centers around the duration of shaking experienced by structures, particularly wooden houses, after the ground shaking from an earthquake has ceased. Participants share personal experiences and observations related to the aftermath of earthquakes, exploring the damping characteristics of various structures.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant notes that their perception of shaking lasted between 30 to 60 seconds, while a newspaper article claimed it was only 10 seconds.
  • Another participant suggests that small buildings typically have significant damping and would not continue to shake for more than a second or two after the ground stops shaking.
  • A participant recounts their experience during a past earthquake, describing how a telephone pole swayed for a few seconds after the ground stopped shaking, and mentions that the shaking of a glass in a hotel room ceased quickly during an aftershock.
  • There is a discussion about the elasticity of a telephone pole compared to other materials, with one participant asserting that it is more elastic than concrete.
  • Concerns are raised about the use of the term "minimal" regarding casualties from past earthquakes, contrasting it with the more severe outcomes of other earthquakes, such as the Haiti earthquake.

Areas of Agreement / Disagreement

Participants express differing views on the duration of shaking experienced by structures after an earthquake, with no consensus reached on the exact time frame or the appropriateness of terminology used to describe the impact of past earthquakes.

Contextual Notes

Participants' claims are based on personal experiences and observations, which may not provide a comprehensive understanding of the physical principles involved in post-earthquake shaking.

Pollywoggy
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I live in northern California and there was a substantial earthquake here yesterday. To me, it seemed as though the shaking continued for somewhere between 30 seconds and 60 seconds, but one newspaper article stated the ground shook for 10 seconds.

Does anyone know how long structures such as houses make from wood continue to shake after the ground shaking subsides?

(I posted here because I did not consider this a "homework" type question)
 
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Most small buildings have a lot of damping/aren't very elastic so they would not continue to shake for more than a second or two after the ground stopped shaking.
 
russ_watters said:
Most small buildings have a lot of damping/aren't very elastic so they would not continue to shake for more than a second or two after the ground stopped shaking.
I've only experienced an earthquake once, a 7.1 in San Fran back in '88 or so, while I was driving my car. The road rolled, I had trouble steering, and I noticed a telephone pole swaying back and forth. After the ground stopped shaking, the pole quickly dampened out in a few seconds, as Russ noted. Back in the hotel room later, an aftershock occurred. A glass on the desktop tipped over, but then the the shaking stopped in barely a second or 2. Having never experienced a quake before, I didn't know it was an earthquake until the radio announcer of the world series game in Oakland, that I was listening to, shouted, "I think we've had an earthquake!'". Fortunately, injuries, destruction, and deaths were minimal, unlike the terrible tragic results of the recent Haiti earthquake, of similar strength.
 
Last edited:
...and a telephone pole is actually reasonably elastic. A lot more elastic than a concrete block.
 
russ_watters said:
...and a telephone pole is actually reasonably elastic. A lot more elastic than a concrete block.
Right, the pole shook for a few seconds; the hotel shaking post quake was minimal.
 
PhanthomJay said:
Fortunately, injuries, destruction, and deaths were minimal, unlike the terrible tragic results of the recent Haiti earthquake, of similar strength.

Around 40 people were killed by the Loma Prieta earthquake in October, 1989. Much less than Haiti 2010, yes; but I don't think 'minimal' is an appropriate description.
 

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