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Moderate Earthquake - L.A.


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http://earthquake.us...ci11001205.html

Earthquake Details

This event has been reviewed by a seismologist.

Magnitude 4.2

Date-Time

Thursday, September 01, 2011 at 20:47:07 UTC

Thursday, September 01, 2011 at 01:47:07 PM at epicenter

Location 34.356°N, 118.455°W

Depth 0.1 km (~0.1 mile) (poorly constrained)

Region GREATER LOS ANGELES AREA, CALIFORNIA

Distances

7 km (4 miles) ESE (110°) from Newhall, CA

8 km (5 miles) N (349°) from Pacoima, CA

8 km (5 miles) N (349°) from San Fernando, CA

8 km (5 miles) SE (145°) from Santa Clarita, CA

39 km (24 miles) NNW (330°) from Los Angeles Civic Center, CA

Location Uncertainty horizontal +/- 0.3 km (0.2 miles); depth +/- 0.7 km (0.4 miles)

Parameters Nph=140, Dmin=6 km, Rmss=0.58 sec, Gp= 22°,

M-type=local magnitude (ML), Version=1

Source

California Integrated Seismic Net:

USGS Caltech CGS UCB UCSD UNR

Event ID ci11001205

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I was at the airport at the time, picking up my business partner, and we didn't notice it. It was mentioned briefly on the local news on the radio-- just in passing. Like someone above said, it's of interest primarily because there's always a chance (5%) that it's a foreshock.

Camera near the bed in case of a night time big one? Does the camera have light?

Blair Witch style night vision quake YouTubes might have potential.

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I was at the airport at the time, picking up my business partner, and we didn't notice it. It was mentioned briefly on the local news on the radio-- just in passing. Like someone above said, it's of interest primarily because there's always a chance (5%) that it's a foreshock.

I have been idly curious about how often foreshocks occur since we were discussing it from 39 floors up after the VA quake. How *good* is that 5% figure? That is, is it based on your own observations or a statistic you picked up?

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I have been idly curious about how often foreshocks occur since we were discussing it from 39 floors up after the VA quake. How *good* is that 5% figure? That is, is it based on your own observations or a statistic you picked up?

It's what the USGS representative says on TV every time we have a good rattle here. I don't know if that figure is specific to Southern California or what-- but that is what the experts always say here.

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It's like a canned response almost from USGS every time there's a quake.....like trixie said....it's generic.....I am from the SF Bay area.....every time there was a quake they would always remind us of the chance of THE BIG ONE.....loma prieta in 89 was big but not really considered the big one.....they always say something like 30% chance of 8.0 or larger over the next 30 years yet in my 32 years there it never happened but the chance never changed over the years....so it's like they make it up or something....doesn't seem to be based on anything....I know they do but the public doesn't get that

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It's like a canned response almost from USGS every time there's a quake.....like trixie said....it's generic.....I am from the SF Bay area.....every time there was a quake they would always remind us of the chance of THE BIG ONE.....loma prieta in 89 was big but not really considered the big one.....they always say something like 30% chance of 8.0 or larger over the next 30 years yet in my 32 years there it never happened but the chance never changed over the years....so it's like they make it up or something....doesn't seem to be based on anything....I know they do but the public doesn't get that

You're confusing what the USGS says with media hype. When we have a quake, the USGS spokesperson very dryly says there's a 5% chance of a larger event-- meaning if it was a 5.1, there's a 5% chance we see a 5.2 or greater in the next 48 hr. I assume this figure is based on statistics. They're qualified experts and scientists-- not to mention our leading authority on seismic activity-- so I don't know why you would say they just make things up. The USGS doesn't talk about the "Big One" and nonsense like that.

I have a feeling what you just posted is "made up".

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You're confusing what the USGS says with media hype. When we have a quake, the USGS spokesperson very dryly says there's a 5% chance of a larger event-- meaning if it was a 5.1, there's a 5% chance we see a 5.2 or greater in the next 48 hr. I assume this figure is based on statistics. They're qualified experts and scientists-- not to mention our leading authority on seismic activity-- so I don't know why you would say they just make things up. The USGS doesn't talk about the "Big One" and nonsense like that.

I have a feeling what you just posted is "made up".

Yes I would agree...I mean Katia was on the Today show this morning :axe:...I also shouldn't have blurted those numbers and imply the USGS doesn't do good science....they do a good job....the truth was I was too lazy to go find what trixie posted which I found interesting.....I know we still know very little about earthquakes and predictions of same....it really is tough to put numbers to it.....

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actually in 1989 it was 66% of a 7.0 or higher between 1990-2020. in 1999, after intensive study the time period was revised to 2000-2030.

there are numerous USGS reports easily accessible its website. here's am excerpt from a relevant document:

http://geopubs.wr.usgs.gov/open-file/of99-517/#_Toc464419639

It's interesting that the chance increased only 3% in ten years......my parents would be toast if those faults went in central and eastern contra costa.....though I believe they are moderate in size.....the Hayward fault is much scarier....

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I suppose it's worthy of a mention because 1) it happened very close to the city and 2) the region is prone to big events-- 6.5 and above-- and any kind of 4+ tremor suggests a heightened risk of something greater in the near future.

Or ArtRosen is a sensationalist poster and thinks a 4.2 in a highly active seismic zone means something. I don't think it suggests anything really. Maybe we need an earthquake and volcano forum.

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