Easter Earthquake In California

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Discussion Overview

The discussion centers around the 6.9 magnitude earthquake that struck Baja California on Easter Sunday, April 4, 2010, and the varying experiences of individuals in California and Arizona during the event. Participants share personal accounts, feelings, and observations related to the earthquake, including its effects and the reactions of those around them.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • Some participants describe their experiences during the earthquake, noting sensations of shaking and swaying in buildings, while others report feeling nothing at all.
  • One participant mentions that the earthquake was initially reported as a 6.9 magnitude but was later upgraded to 7.2.
  • Several individuals express confusion about the timing of the quake's impact in Los Angeles, questioning how it could have been felt differently by various people.
  • Participants discuss the instinctive reactions during the quake, such as standing up or seeking shelter, and the indecision about whether to stay indoors or go outside.
  • There are mentions of potential hazards associated with running outside during an earthquake, including falling debris and glass.
  • Some participants reference the geological factors that influence the perception of earthquakes, such as wave frequency and local geology.
  • One participant shares a picture of damage in Mexico near the epicenter, while others report minimal effects in their locations.
  • There are discussions about the nature of aftershocks and the frequency of earthquakes in Southern California and Baja California.

Areas of Agreement / Disagreement

Participants express a range of experiences and perceptions regarding the earthquake, with no consensus on its impact. Some felt strong shaking while others did not feel it at all, indicating multiple competing views on the event.

Contextual Notes

Participants mention various factors that may influence the experience of an earthquake, including building construction, distance from the epicenter, and local geological conditions. There is also a reference to the historical context of earthquake preparedness and safety advice.

Who May Find This Useful

Individuals interested in personal accounts of seismic events, earthquake preparedness, and the variability of earthquake experiences across different locations may find this discussion relevant.

  • #31
DaveC426913 said:
I find this interesting. If the ground simply shook, one might expect some choppy waves but, ultimately, no displacement.

You describe a tsumani-like effect, which I'm going to go out on a limb and assume means a large sloshing back and forth.

It seems to me, this is a strong indication of, not just lateral oscillation (where the net movement is zero), but of lateral displacement (where the net movement is significant).

In the Chile earthquake last month, one of the tdibits that was reported was that the city of Concepcion and its surrounding countryside is now 10 feet to the left of where it was.
http://researchnews.osu.edu/archive/chilequakemap.htm

Heh. Anyone got a high-end GPS? I wonder if your house is still sitting where it was before the quake...

Well, this is a Strike-Slip fault, so the displacement shouldn't be too significant. I suspecpt the "pool" effect had more to do with the depth of the quake.
 
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  • #32
DaveC426913 said:
Heh. Anyone got a high-end GPS? I wonder if your house is still sitting where it was before the quake...

no...

my house moved, and...

is still moving...

at about 100,000 mph
 
  • #33
rewebster said:
no...

my house moved, and...

is still moving...

at about 100,000 mph

Relative to the geosat coordinates?? You better go catch it!
 
  • #34
DaveC426913 said:
Relative to the geosat coordinates?? You better go catch it!

Am I the only one who immidiately thought of "Is your refrigerator running?..." :-p

Hey... and wouldn't a "highly accurate" GPS be a military GPS?! Scaaary forum! :smile:
 
  • #35
Frame Dragger said:
Am I the only one who immidiately thought of "Is your refrigerator running?..."
You nailed it. :smile:
 
  • #36
Ivan Seeking said:
Checkout the dust cloud generated in the desert hills of Mexicali [presumably].
http://www.ireport.com/docs/DOC-428979?hpt=C2
I just became aware today that Calexico had major damage. Video on TV showed split roads, traffic lights fallen over onto cars, buildings shaken to funny angles.

No people seriously injured, but the economy was already bad there, so now they're thinking it's going to be depressed for years. The downtown businesses and the city infrastructure suffered major blows.
 
  • #37
Frame Dragger said:
What I find amusing is that the same people who take this in stride, might be the same people who think strangers always kidnap children...
You mean the candy people? I like the candy people!

But seriously, I have lived here all of my life. I have yet to be in an earthquake where, in my immediate vicinity, there was more damage than a picture that fell off the wall.

I know that there are big earthquakes and they can cause some serious damage but the vast majority of them are nothing but a bit of a shake up. Its like freaking out every time it rains because hurricanes do lots of damage.
 
  • #38
TheStatutoryApe said:
But seriously, I have lived here all of my life. I have yet to be in an earthquake where, in my immediate vicinity, there was more damage than a picture that fell off the wall.

I know that there are big earthquakes and they can cause some serious damage but the vast majority of them are nothing but a bit of a shake up. Its like freaking out every time it rains because hurricanes do lots of damage.

The thing is, geologists have been saying that San Diego is overdue for a big one. The geological record indicates this area is the epicenter of a 7. + quake every hundred and something years, and we're about 30 years overdue. This is why each one I can feel alarms me till it's over.
 
  • #39
zoobyshoe said:
The thing is, geologists have been saying that San Diego is overdue for a big one. The geological record indicates this area is the epicenter of a 7. + quake every hundred and something years, and we're about 30 years overdue. This is why each one I can feel alarms me till it's over.

Indeed, especially as "overdue" often means a larger energy release. Of course, what the news doesn't cover (not horrifying) is that faults can have that same potential sapped by a number of smaller quakes.

So.. this could be very VERY bad, or it could be you never have to see more than pictures fall. I hope (I'm guessing as you do!) for the latter.
 
  • #40
Frame Dragger said:
Indeed, especially as "overdue" often means a larger energy release. Of course, what the news doesn't cover (not horrifying) is that faults can have that same potential sapped by a number of smaller quakes.

So.. this could be very VERY bad, or it could be you never have to see more than pictures fall. I hope (I'm guessing as you do!) for the latter.
Yes, the "overdue" seems to indicate things have gotten stuck on a particularly difficult spur, as it were, which would mean a much larger quake when that finally gives way. On the other hand it could mean that the past regular quakes already succeeded in grinding down a particularly difficult spur, and that is the reason there has not been another big one in the series. In any event, I once saw a map of all the faults under San Diego. It looked like a peanut butter cookie that someone had sat on: it's in a million pieces.
 
  • #41
zoobyshoe said:
Yes, the "overdue" seems to indicate things have gotten stuck on a particularly difficult spur, as it were, which would mean a much larger quake when that finally gives way. On the other hand it could mean that the past regular quakes already succeeded in grinding down a particularly difficult spur, and that is the reason there has not been another big one in the series. In any event, I once saw a map of all the faults under San Diego. It looked like a peanut butter cookie that someone had sat on: it's in a million pieces.

I'm sorry, I know I shouldn't, but that last sentence had me in stitches! Of course you're absolutely right, and here's to hoping that this 100-130 years just missed a "big one" or that this fault will be less... energetic. Unlike a subduction zones, slip-strikes can have much longer periods of "calm".
 
  • #42
Frame Dragger said:
I'm sorry, I know I shouldn't, but that last sentence had me in stitches! Of course you're absolutely right, and here's to hoping that this 100-130 years just missed a "big one" or that this fault will be less... energetic. Unlike a subduction zones, slip-strikes can have much longer periods of "calm".

Yeah, I guess that sounded funnier than I meant it to.

I certainly hope any large buildup of potential energy is frittered away in small quakes.
 
  • #43
zoobyshoe said:
Yeah, I guess that sounded funnier than I meant it to.

I certainly hope any large buildup of potential energy is frittered away in small quakes.

I'll drink (well.. ok, I don't, but I WOULD) to that!

On a related note, the prediction now is for a very strong Atlantic hurricane season. That is NOT going to be good news for Haiti, and if we had a major quake in the USA, we would divert resources even more from those who literally couldn't live without it. Hell, they may not anyway. :sad:
 
  • #44
zoobyshoe said:
The thing is, geologists have been saying that San Diego is overdue for a big one. The geological record indicates this area is the epicenter of a 7. + quake every hundred and something years, and we're about 30 years overdue. This is why each one I can feel alarms me till it's over.

Sorry Zoob. I do not mean to demean your, or anyones, concern regarding earthquakes. For those who have never experienced them I'm sure that even a small one is rather surprising to say the least.
 
  • #45
TheStatutoryApe said:
Sorry Zoob. I do not mean to demean your, or anyones, concern regarding earthquakes. For those who have never experienced them I'm sure that even a small one is rather surprising to say the least.

What can I say? The ground should not be moving around.

I'm not a fan of volcanoes either.
 
  • #46
zoobyshoe said:
What can I say? The ground should not be moving around.

I'm not a fan of volcanoes either.

Yeah... the latter really can be terrifying, especially the notion of something like Yellowstone blowing its top. :eek: Then again, that probably is the answer to my earlier question: you can't run from nature in the end.
 
  • #47
zoobyshoe said:
What can I say? The ground should not be moving around.

Duct tape to the rescuuuuuuue!
 

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