Micro quake minutes before explosion!

I didn't see it on the map last night but today, I did. And, on the Earthwaves forum, they discussed the fact that if they try to blame the event on an earthquake, it will mess with people's insurance claims. No earthquake insurance, no nada.

Bear in mind that the explosion happened at 6:14pm. I suspect it was the explosion that caused the "micro-quake" but of not, it's sure going to muddy the whole affair.

A micro earthquake occurred at 6:11:12 PM (PDT) on Thursday, September 9, 2010.
The magnitude 1.1 event occurred 4 km (2 miles) ENE (75 degrees) of Pacifica, CA.
The hypocentral depth is 0 km (0.0 miles).



Magnitude 1.1 - duration magnitude (Md)
Time Thursday, September 9, 2010 at 6:11:12 PM (PDT)
Friday, September 10, 2010 at 1:11:12 (UTC)
Distance from Pacifica, CA - 4 km (2 miles) ENE (75 degrees)
South San Francisco, CA - 5 km (3 miles) SW (221 degrees)
Millbrae, CA - 6 km (3 miles) WNW (299 degrees)
San Francisco City Hall, CA - 17 km (11 miles) S (187 degrees)

Coordinates 37 deg. 37.4 min. N (37.623N), 122 deg. 26.5 min. W (122.442W)
Depth 0 km (0.0 miles)
Quality Good
http://www.data.scec.org/recenteqs/Quakes/nc71453305.html


Seems to be another micro quake listed there that happened today?
You can view the waveforms at the link.
Redhart, what do you think

I specifically looked for an earthquake last night and didn't see one either. Interesting.

That is one of the first things I did last night after the explosion - checked out USGS for a small quake in that area. It was such a large explosion, and with the SAF being right there I thought it might set off a small quake at the surface. Thanks for posting this. I feel so sorry for all of those people.

Polly, AZ wrote:That is one of the first things I did last night after the explosion - checked out USGS for a small quake in that area. It was such a large explosion, and with the SAF being right there I thought it might set off a small quake at the surface. Thanks for posting this. I feel so sorry for all of those people.

So Polly you didn't say whether you saw it or not you looked and what did you see. Curious

if Polly looked when I did which was nearly 11pm last night, by the time I thought to look, there was no quake in that area showing on the USGS/CA map.

It showed up sometime this morning, but can't remember exactly when - between 9-11am? Isn't that curious when they must have seen the waveforms as shown on the chart at my link in the 1st post.

I'd be really interested if Don in Hollister or Redhart would look at the waveforms graphs, see what they think.
Must be an explanation somewhere. If it was an actual micro quake that caused that pipe to burst then - well we will see what comes out in the investigations I guess??? That's if we ever hear anything about it!

I took the coordinates, fed them into google maps and voila, you can see from the map how close it was. To the east of the church on the map of the quake is "Crestmoor Drive" (across from Crestmoor Canyon) which is nearly the epicenter of the explosion.

Here's the google map:
http://maps.google.com/maps?f=s&utm_campaign=en&utm_source=en-ha-na-us-sk-gm&utm_medium=ha&utm_term=map

oops, I goofed . Should have added a 3 to the N. coordinate. I saw Redhart's USGS link on the other thread, and saw that the map above is wrong.
So it appears that the micro quake is exactly where the explosion was.
I saw so many pictures of the impact area with that huge crater, I should have known. Oh well back to the drawing board .

The California Integrated Seismic Network operated by the U.S. Geological Survey, UC Berkeley, and the California Geological Survey recorded seismic waves generated by the gas explosion in San Bruno, CA. The time of the explosion is September 09, 2010 at 06:11:12 PM PDT. The observed arrival times of energy on nearby seismic stations are consistent with a location having coordinates of the explosion. Two of the U.S. Geological Survey "NetQuakes" strong motion stations (J022 and J039)(http://earthquake.usgs.gov/monitoring/netquakes/) were within 1 km of the explosion and recorded peak ground motions of 1.9 and 0.01 cm/s/s (0.2 and 0.01%g), respectively. Energy was not recorded beyond 14 km. There is evidence for only one blast, as can be seen on a helicorder record for a seismic station 3km northwest of the explosion site http://ncsn.wr.usgs.gov/cgi-bin/heli2go.pl?3&JMGB_NC_EHZ_--_00&20100910.

That IS the explosion
It was added later...early this morning.
http://earthquake.usgs.gov/earthquakes/recenteqsus/Quakes/nc71453305.html#summary

geenee wrote:I specifically looked for an earthquake last night and didn't see one either. Interesting.

I didn't see one either. I'm sure that was one of the first things that most of us looked for, and all I'm hearing on the news and online is they can't agree on what triggered the explosion.
BTW, did you see the crater the blast left in the ground?
I was only able to spot it once on the live streaming feeds AND on tv.
I will have to ask brother in law as he lives just south of there.

Redhart wrote:

The California Integrated Seismic Network operated by the U.S. Geological Survey, UC Berkeley, and the California Geological Survey recorded seismic waves generated by the gas explosion in San Bruno, CA. The time of the explosion is September 09, 2010 at 06:11:12 PM PDT. The observed arrival times of energy on nearby seismic stations are consistent with a location having coordinates of the explosion. Two of the U.S. Geological Survey "NetQuakes" strong motion stations (J022 and J039)(http://earthquake.usgs.gov/monitoring/netquakes/) were within 1 km of the explosion and recorded peak ground motions of 1.9 and 0.01 cm/s/s (0.2 and 0.01%g), respectively. Energy was not recorded beyond 14 km. There is evidence for only one blast, as can be seen on a helicorder record for a seismic station 3km northwest of the explosion site http://ncsn.wr.usgs.gov/cgi-bin/heli2go.pl?3&JMGB_NC_EHZ_--_00&20100910.

That IS the explosion
It was added later...early this morning.
http://earthquake.usgs.gov/earthquakes/recenteqsus/Quakes/nc71453305.html#summary

Why was it added later

thanks Redhart, I'm glad to hear that USGS updated this micro quake. Had the explosion been caused by the quake, anybody who didn't have quake insurance would be left without funds to rebuild unless declared a fed. disaster so they could get low int. loans.

Oddly enough, I did read that 1 of the fire deaths was a woman who worked for the state and her job was to oversee the Gas industry! She and her daughter perished in the explosion because her home was just across the street from the blast.

Someone posted a link to a google map that shows the streets with the most damage, and other info on the blast as well. You can switch to satellite view and from that see that the pipe really close to the edge of a pretty steep canyon. So I'm thinking that erosion right there had a play in the blast too, especially if the water main had been leaking.

http://maps.google.com/maps/ms?msa=0&msid=115203651140089107127.00048fdfe759741e3afd2

geenee wrote:

Polly, AZ wrote:That is one of the first things I did last night after the explosion - checked out USGS for a small quake in that area. It was such a large explosion, and with the SAF being right there I thought it might set off a small quake at the surface. Thanks for posting this. I feel so sorry for all of those people.

So Polly you didn't say whether you saw it or not you looked and what did you see. Curious

The last I checked USGS on the night of the SF gas explosion was around midnight and no quake reported as of then, but it was there the following morning.

Sheila, Or. wrote:if Polly looked when I did which was nearly 11pm last night, by the time I thought to look, there was no quake in that area showing on the USGS/CA map.

It showed up sometime this morning, but can't remember exactly when - between 9-11am? Isn't that curious when they must have seen the waveforms as shown on the chart at my link in the 1st post.

I'd be really interested if Don in Hollister or Redhart would look at the waveforms graphs, see what they think.
Must be an explanation somewhere. If it was an actual micro quake that caused that pipe to burst then - well we will see what comes out in the investigations I guess??? That's if we ever hear anything about it!

Sheila - last I looked at USGS the night of the explosion was around midnight and the quake hadn't been reported yet, but it was there in the morning. Since many in that area had been smelling gas fumes from the sewer for about 3 weeks or more,I was wondering if the movement of a small 1.1 quake might have sparked the explosion? It wouldn't be any different then standing in a gas filled room and striking 2 flints together.

yeah, I was wondering but seeing that the explosion was so huge, it did register on the seismographs, it prolly took the USGS guys some time to figure it out.
They might not be as well connected to the news as we all are on the earthboppin forums, and boy did we all do a good job of reporting whatever we could find.
CNN, none of them said anything for the longest time!
Maybe Homeland Insecurity told USGS to wait till they investigated? Who knows.
One thing is for sure, an explosion, rockfall, stuff that happens like that, often shows up on the seismos.
Oh boy do I ever have alot of quake symptoms today too!
No time to post them all but am waiting and watching.

Sheila, Or. wrote:yeah, I was wondering but seeing that the explosion was so huge, it did register on the seismographs, it prolly took the USGS guys some time to figure it out.
They might not be as well connected to the news as we all are on the earthboppin forums, and boy did we all do a good job of reporting whatever we could find.
CNN, none of them said anything for the longest time!
Maybe Homeland Insecurity told USGS to wait till they investigated? Who knows.
One thing is for sure, an explosion, rockfall, stuff that happens like that, often shows up on the seismos.
Oh boy do I ever have alot of quake symptoms today too!
No time to post them all but am waiting and watching.

Sheila - I think that most of the news stations get a LOT of their information from webbots like this one. I have noticed a few times that we may have a thread going and sure enough a news station will report what we are thingking about 1 to 3 days later. Maybe we should all be on their payroll !

They might not be as well connected to the news as we all are on the earthboppin forums, and boy did we all do a good job of reporting whatever we could find.

Indeed... Just want to thank everyone too.
I love the network these forums have become.
Lots of information and ideas about things that are happning.
It always feels good to check in!
Thanks all!
Vim

Hi All. After looking at all of the seismographs that recorded the gas line explosion I can find no quake other then the one caused by the explosion. Take Care...Don

Vim/PA wrote:

They might not be as well connected to the news as we all are on the earthboppin forums, and boy did we all do a good job of reporting whatever we could find.

Indeed... Just want to thank everyone too.
I love the network these forums have become.
Lots of information and ideas about things that are happning.
It always feels good to check in!
Thanks all!
Vim

Thats the joy of havng a forum where we all have different opinions of how things happen.
We all get busy and dig up information to prove our point of view. LOL