# Earthquake aftershocks **URL:** \ **Category:** Cecil's Columns/Staff Reports\ **Created:** [September 27, 1999, 3:17am UTC](https://boards.straightdope.com/t/earthquake-aftershocks/1376 "1999-09-27T03:17:00Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![JillGat](https://avatars.discourse-cdn.com/v4/letter/j/9fc29f/32.png) [@JillGat](https://boards.straightdope.com/u/JillGat)\ **Post date:** [September 27, 1999, 3:17am UTC](https://boards.straightdope.com/t/earthquake-aftershocks/1376/1 "1999-09-27T03:17:00Z")
From Reuter’s news online today: [[The breakfast-hour aftershock, at 6.8 on the Richter scale, qualified as a serious quake in its own right. But it was the third of that magnitude among some 7,100 tremors since the big …]] This, of course, is not actually true. It does not qualify as a “serious quake in its own right.” It qualifies as an aftershock. See: [http://www.straightdope.com/mailbag/maftershock.html](http://www.straightdope.com/mailbag/maftershock.html) ---
**Author:** ![AuraSeer](https://avatars.discourse-cdn.com/v4/letter/a/c2a13f/32.png) [@AuraSeer](https://boards.straightdope.com/u/AuraSeer)\ **Post date:** [September 27, 1999, 6:05pm UTC](https://boards.straightdope.com/t/earthquake-aftershocks/1376/2 "1999-09-27T18:05:00Z")
I think the point was that a 6.8 on the Richter denotes a lot of shaking. Even if the area had been earthquake-free for years, a single shock of that magnitude would be noted as a significant quake. It’s not as if reporters usually go for scientific accuracy, after all… ---
**Author:** ![JillGat](https://avatars.discourse-cdn.com/v4/letter/j/9fc29f/32.png) [@JillGat](https://boards.straightdope.com/u/JillGat)\ **Post date:** [September 27, 1999, 10:52pm UTC](https://boards.straightdope.com/t/earthquake-aftershocks/1376/3 "1999-09-27T22:52:00Z")
[[I think the point was that a 6.8 on the Richter denotes a lot of shaking. Even if the area had been earthquake-free for years, a single shock of that magnitude would be noted as a significant quake.]] Right. If there hadn’t been another earthquake in a really long time (see mailbag answer for specifics on how this is determined), it _would_ have been a “quake in its own right.” However even a strong quake - if it’s not stronger than the mainquake - is called an aftershock. I agree, though, that the point being made is that a whole lotta shakin was goin on. ---
**Author:** ![RM\_Mentock](https://avatars.discourse-cdn.com/v4/letter/r/e274bd/32.png) [@RM\_Mentock](https://boards.straightdope.com/u/RM_Mentock)\ **Post date:** [December 8, 1999, 8:23am UTC](https://boards.straightdope.com/t/earthquake-aftershocks/1376/4 "1999-12-08T08:23:00Z")
Jill I gotta disagree on this one. Even your column doesn’t back you up. It uses the phrase “There’s a rule of thumb that an earthquake is an aftershock…” If an aftershock isn’t an earthquake, how can a earthquake be an aftershock? The distinction in the column was between mainshocks and aftershocks, not between earthquakes and aftershocks. ---
**Author:** ![jab1](https://avatars.discourse-cdn.com/v4/letter/j/ee7513/32.png) [@jab1](https://boards.straightdope.com/u/jab1)\ **Post date:** [December 8, 1999, 8:56pm UTC](https://boards.straightdope.com/t/earthquake-aftershocks/1376/5 "1999-12-08T20:56:00Z")
Go to: [http://www-socal.wr.usgs.gov/hough/eos.html](http://www-socal.wr.usgs.gov/hough/eos.html) for info on the Landers-Big Bear event of 1992. The article defines the terms “aftershock”, “main shock” and “foreshock.” The Landers-Big Bear event surprised even jaded veterans here in Southern California because it was two separate events happening many miles apart, on two separate fault lines _in the same morning_. What a wake-up call _that_ was! I remember stumbling around half-awake, grateful the lights still worked, switching on the TV and channel-surfing to find out where the 'quake had hit and how big it was. Then, about an hour later, IIRC, the Big Bear jolt struck and I’m standing in the bathroom doorway watching a lamp hanging from the ceiling swing back and forth on its own. (They tell you to stand in a doorway to avoid being hit by a falling ceiling and/or walls. This works only if the tremor is too weak to bring down the whole building, of course. :)) Anyway, I hope this helps. * * * Fighting my own ignorance since 1957. ---
**Author:** ![RM\_Mentock](https://avatars.discourse-cdn.com/v4/letter/r/e274bd/32.png) [@RM\_Mentock](https://boards.straightdope.com/u/RM_Mentock)\ **Post date:** [December 8, 1999, 10:39pm UTC](https://boards.straightdope.com/t/earthquake-aftershocks/1376/6 "1999-12-08T22:39:00Z")
Although I have little, very little, personal experience in earthquakes, I’m told that the standing in the doorway trick might help some even if the whole building falls down–it might keep you alive long enough to be rescued. Anyway, that link doesn’t say that you can’t refer to an aftershock as a quake. Or was Jill referring to something else? (She’s on vacation, right, and we’re not, so we can talk about her.) ---
**Author:** ![jab1](https://avatars.discourse-cdn.com/v4/letter/j/ee7513/32.png) [@jab1](https://boards.straightdope.com/u/jab1)\ **Post date:** [December 9, 1999, 3:54am UTC](https://boards.straightdope.com/t/earthquake-aftershocks/1376/7 "1999-12-09T03:54:00Z")
If I’m on the 14th Floor and the whole building comes down, I don’t think it matters too much whether I’m standing in a doorway or not. Haven’t you seen those pictures from Taiwan and Turkey where multi-story buildings toppled over like Godzilla just came through? Then, of course, you could be like those folks in Northridge on the ground floor who died when the supporting walls collapsed and the upper floors “pancaked” on top of them. What do I do? I make sure the building I live in has passed inspection and is as structurally sound as can be, knowing that NO building can be built 100% indestructible. It’s that, or live somewhere else and I like it here. * * * Fighting my own ignorance since 1957. ---
**Author:** ![JillGat](https://avatars.discourse-cdn.com/v4/letter/j/9fc29f/32.png) [@JillGat](https://boards.straightdope.com/u/JillGat)\ **Post date:** [December 9, 1999, 4:18am UTC](https://boards.straightdope.com/t/earthquake-aftershocks/1376/8 "1999-12-09T04:18:00Z")
[[Anyway, that link doesn’t say that you can’t refer to an aftershock as a quake. Or was Jill referring to something else? (She’s on vacation, right, and we’re not, so we can talk about her.)]] Nope, not yet I’m not gone yet, Big Boy. You are technically right that any of the “shocks” can be referred to as earthquakes. But the story I was referring to was using the term to describe the mainshock, and then using the term again to describe the aftershock as another mainshock, in my opinion (“an earthquake in its own right”). I think. But I’m not gonna go back and look because mentally I am already away on vacation. Jill ---
**Author:** ![RM\_Mentock](https://avatars.discourse-cdn.com/v4/letter/r/e274bd/32.png) [@RM\_Mentock](https://boards.straightdope.com/u/RM_Mentock)\ **Post date:** [December 9, 1999, 10:52am UTC](https://boards.straightdope.com/t/earthquake-aftershocks/1376/9 "1999-12-09T10:52:00Z")
> [@](#): > > [[Anyway, that link doesn’t say that you can’t refer to an aftershock as a quake. Or > was Jill referring to something else? (She’s on vacation, right, and we’re not, so we can > talk about her.)]] > > Nope, not yet I’m not gone yet, Big Boy. Oh. Have a good vacation! (Arghhh. Why didn’t someone tell me she was still here?) . ---
**Author:** ![JillGat](https://avatars.discourse-cdn.com/v4/letter/j/9fc29f/32.png) [@JillGat](https://boards.straightdope.com/u/JillGat)\ **Post date:** [December 9, 1999, 8:40pm UTC](https://boards.straightdope.com/t/earthquake-aftershocks/1376/10 "1999-12-09T20:40:00Z")
[[Oh. Have a good vacation! (Arghhh. Why didn’t someone tell me she was still here?)]] Wuss. ``` . ``` ---
**Author:** ![RM\_Mentock](https://avatars.discourse-cdn.com/v4/letter/r/e274bd/32.png) [@RM\_Mentock](https://boards.straightdope.com/u/RM_Mentock)\ **Post date:** [December 9, 1999, 11:20pm UTC](https://boards.straightdope.com/t/earthquake-aftershocks/1376/11 "1999-12-09T23:20:00Z")
> [@](#): > > Wuss. OK, that’s it. I’ve had enough of this crap. You don’t know what you’ve started. I’m never ever going to criticize you again. ---
**Author:** ![JillGat](https://avatars.discourse-cdn.com/v4/letter/j/9fc29f/32.png) [@JillGat](https://boards.straightdope.com/u/JillGat)\ **Post date:** [December 10, 1999, 4:13am UTC](https://boards.straightdope.com/t/earthquake-aftershocks/1376/12 "1999-12-10T04:13:00Z")
Oh man, now I’ve done it. I’ve pissed off the guy who’s gonna solve the Chandler wobble. ---
**Author:** ![jab1](https://avatars.discourse-cdn.com/v4/letter/j/ee7513/32.png) [@jab1](https://boards.straightdope.com/u/jab1)\ **Post date:** [December 11, 1999, 11:37pm UTC](https://boards.straightdope.com/t/earthquake-aftershocks/1376/13 "1999-12-11T23:37:00Z")
Well, there was another earthquake, this one in the Phillippines, a 6.8, according to [http://cnn.com/](http://cnn.com/) Let’s see if they get the terms correct. * * * \>\< DARWIN \> \_\_ **L\_\_\_L** ---
**Author:** ![Shayna](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/shayna/32/17976_2.png) [@Shayna](https://boards.straightdope.com/u/Shayna)\ **Post date:** [December 12, 1999, 10:17am UTC](https://boards.straightdope.com/t/earthquake-aftershocks/1376/14 "1999-12-12T10:17:00Z")
RM Mentock posted > [@](#): > > Although I have little, very little, personal experience in earthquakes, I’m told that the standing in the doorway trick might help some even if the whole building falls down–it might keep you alive long enough to be rescued. I heard that that’s actually a fallacy. Standing in a doorway can be dangerous because if the quake is strong enough, the door can swing hard enough to knock you out. I learned in an earthquake preparedness course that the best place to be is lying down on the floor next to (not under) the bed. If you’re under it, of course it could collapse on you if the ceiling falls on it. But if you’re next to it and either the ceiling or walls fall in, it creates a pocket so you don’t get crushed (Crude illustration below). That way you have a greater chance of being able to either crawl out to safety or call out for help if you’re trapped since you’re (hopefully) not unconscious. \_\_\_\_\_\ \<-----wall or ceiling |_bed_| | |x ^ | you So does anyone know where the safest place to be _really_ is? * * * “The trouble with the rat race is that even if you win, you’re still a rat.” – Lily Tomlin ---
**Author:** ![Shayna](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/shayna/32/17976_2.png) [@Shayna](https://boards.straightdope.com/u/Shayna)\ **Post date:** [December 12, 1999, 10:20am UTC](https://boards.straightdope.com/t/earthquake-aftershocks/1376/15 "1999-12-12T10:20:00Z")
Man, I wish we had preview!! The drawing looked ok when I typed it in the message box. [hanging my head in shame at the mess above] Oh well, I think you get the idea. [/head hanging] ---
**Author:** ![Bubba\_blue](https://avatars.discourse-cdn.com/v4/letter/b/e19b73/32.png) [@Bubba\_blue](https://boards.straightdope.com/u/Bubba_blue)\ **Post date:** [December 19, 1999, 6:48am UTC](https://boards.straightdope.com/t/earthquake-aftershocks/1376/16 "1999-12-19T06:48:00Z")
Shayna asked: > [@](#): > > So does anyone know where the safest place to be really is? Calgary. ---
**Author:** ![JillGat](https://avatars.discourse-cdn.com/v4/letter/j/9fc29f/32.png) [@JillGat](https://boards.straightdope.com/u/JillGat)\ **Post date:** [December 20, 1999, 6:34am UTC](https://boards.straightdope.com/t/earthquake-aftershocks/1376/17 "1999-12-20T06:34:00Z")
Too cold in Calgary. Albuquerque. ---
**Author:** ![Diceman](https://avatars.discourse-cdn.com/v4/letter/d/22d042/32.png) [@Diceman](https://boards.straightdope.com/u/Diceman)\ **Post date:** [December 19, 1999, 8:11pm UTC](https://boards.straightdope.com/t/earthquake-aftershocks/1376/18 "1999-12-19T20:11:00Z")
> [@](#): > > Too cold in Calgary. Albuquerque. It’s not the humidity. It’s the heat. Kentucky or Tennessee. ---
**Author:** ![RM\_Mentock](https://avatars.discourse-cdn.com/v4/letter/r/e274bd/32.png) [@RM\_Mentock](https://boards.straightdope.com/u/RM_Mentock)\ **Post date:** [December 20, 1999, 7:10am UTC](https://boards.straightdope.com/t/earthquake-aftershocks/1376/19 "1999-12-20T07:10:00Z")
Tennessee? Don’t be too sure. Here’s a discussion of the Southern Appalachian Seismic Zone and its similarity to the New Madrid Seismic Zone, where some of the greatest earthquakes in US history occurred. [http://tanasi.gg.utk.edu/NMSZvsSASZ.html](http://tanasi.gg.utk.edu/NMSZvsSASZ.html) . ---
**Author:** ![JillGat](https://avatars.discourse-cdn.com/v4/letter/j/9fc29f/32.png) [@JillGat](https://boards.straightdope.com/u/JillGat)\ **Post date:** [December 21, 1999, 1:08am UTC](https://boards.straightdope.com/t/earthquake-aftershocks/1376/20 "1999-12-21T01:08:00Z")
Raise your hand if you think Mentock is getting a bit insufferable since getting that Chandler Wobble question published? Jill [Next page](https://boards.straightdope.com/t/earthquake-aftershocks/1376.md?page=2)