Earthquake in BRC

wedeliver · Post by **wedeliver** » Sun Sep 28, 2008 6:06 pm

Small earthquake 15 miles North East of Gerlach Nevada.
Well there goes the property values.

http://quake.usgs.gov/recenteqs/Maps/119-41.html

The link above will expire in one week if there are no more earthquakes in the area.

dr.placebo · Post by **dr.placebo** » Sun Sep 28, 2008 6:17 pm

Could be a quarry explosion. Note that the initial depth estimate is 0 km, which puts it on the surface.

Or it could be the aliens looking for MOOP. They're a bit late.

gyre · Post by **gyre** » Sun Sep 28, 2008 6:49 pm

Only 1.8.
Could be a bored burner.

motskyroonmatick · Post by **motskyroonmatick** » Sun Sep 28, 2008 7:53 pm

gyre wrote:Only 1.8.
Could be a bored burner.

Trying to make a new hot spring or augment an old one?

gyre · Post by **gyre** » Sun Sep 28, 2008 8:02 pm

"I was bored and I had some propane left"
(meaning 400-500 lbs)

What a girl said to me late one night, after setting off a fuel air explosion over our camp with no notice.

That actually made sense to me.

ygmir · Post by **ygmir** » Sun Sep 28, 2008 8:06 pm

gyre wrote:"I was bored and I had some propane left"
(meaning 400-500 lbs)

What a girl said to me late one night, after setting off a fuel air explosion over our camp with no notice.

That actually made sense to me.

did you propose marriage on the spot?

gyre · Post by **gyre** » Sun Sep 28, 2008 8:17 pm

I should have proposed something, shouldn't I?

littleflower · Post by **littleflower** » Sun Sep 28, 2008 8:26 pm

so ... there were no earthquakes of this magnitude near BRC at the end of august ???? something is wrong here...

wedeliver · Post by **wedeliver** » Sun Sep 28, 2008 8:38 pm

littleflower wrote:so ... there were no earthquakes of this magnitude near BRC at the end of august ???? something is wrong here...

I do not recall any earthquake in that area of Nevada in 13 years of observing. Although it is a fault line, just like the "Wells" swarm a year or two ago.

gyre · Post by **gyre** » Sun Sep 28, 2008 8:46 pm

Wasn't there a 5 last year?

ygmir · Post by **ygmir** » Sun Sep 28, 2008 8:58 pm

seems I remember seeing one on the USGS site the first part of Sept. in or near BRC

Badger · Post by **Badger** » Sun Sep 28, 2008 10:00 pm

I do not recall any earthquake in that area of Nevada in 13 years of observing. Although it is a fault line, just like the "Wells" swarm a year or two ago.

The Basin and Range provence is the most seismacally active area of the second most actively state in the US.

Earthquakes and temblors happen there every day.

theCryptofishist · Post by **theCryptofishist** » Sun Sep 28, 2008 11:48 pm

So where does California rank? #4? And Hawai'i's number 1?

RingO'Fire · Post by **RingO'Fire** » Mon Sep 29, 2008 8:17 am

Badger wrote:The Basin and Range provence is the most seismacally active area of the second most actively state in the US.

Earthquakes and temblors happen there every day.

Fishy wrote:So where does California rank? #4? And Hawai'i's number 1?

I've got this wall map of earthquakes, plate tectonics, volcanoes, and impact craters in my office (I'm looking at it now) prepared by the U.S. Geological Survey, the Smithsonian & the U.S. Naval Research Lab. (I'm a geologist by training and vocation, and am a bit of a science nerd as well.)

There's an interactive version of the map at this website:
http://nhb-arcims.si.edu/minsci/tdpmap/viewer.htm

You can zoom in on the western U.S. The State political boundaries aren't shown, but Nevada and is due east of the Central Valley of California. The Basin and Range is the tan and mustard colored area of roughly parallel north-northeast to south-southwest trending mountain ranges.

Earthquakes are represented on this map by circles. The size of the circle is proportional to the magnitude (remember though, the Richter scale is a logarithmic scale, so a 1.8 on the Richter scale = 10^1.8 Likewise, a 3 = 10^3, a 4 = 10^4 and so on.) The color of the earthquake circles represents the depth of the earthquakes. Black = shallow, gray = deep.

This pattern of having bands of shallow earthquakes immediately adjacent to bands of deeper earthquakes at subduction zones (a convergent plate boundary - where one plate is plunging beneath another) was one of the lines of evidence that allowed scientists in the 1960's to piece together the whole theory of plate tectonics.

I wasn't exactly sure how the states line up in rank of most to least seismically active, so, being curious, I Googled it. I found this 2006 article from Science Daily "Exhaustive Use Of Seismic Records Ranks Top 10 States For Earthquake Activity." Here's the link: http://www.sciencedaily.com/releases/20 ... 182103.htm.

They say Alaska = #1, California = #2 and Hawaii and Nevada are essentially tied for #3.

wedeliver · Post by **wedeliver** » Mon Sep 29, 2008 8:18 am

Alaska #1, California #2, Hawaii #3

http://earthquake.usgs.gov/regional/sta ... states.php

During the study period Hawaii had twice as many earthquakes as Nevada.

Sure neat to see a pro (above post) joining in! Thanks

chiefdanfox · Post by **chiefdanfox** » Mon Sep 29, 2008 9:39 am

Well, if you look at the period that humans have been recording seismic activity, then Nevada looks relatively calm compared to Alaska and California. But the trick is to look at the evidence over time. The Sierra Nevada is climbing about 1,000 feet per 1 million years, and many areas of the Basin and Range are collapsing much faster than that. The causes of the orogenic collapse are still a bit of a challenge to get folks to agree on, but the amount and speed are not really open to much interpretation.

The amount and speed means a lot of earth movement = quakes. There are a number of recent and prominent downfaulted scarps (graben) in western Nevada, easily discerned by even an untrained eye. We are talking big quakes, 6-7 mag. range.

This is a a fault map showing the vertical slip rates (meters per 1,000 years). There are some pretty speedy ones near BRC.
http://www.seismo.unr.edu/htdocs/nv-faults.html

(BRC is located in that "panhandle" of the county northeast of Reno/Tahoe...this map could use a few more labels, like county labels, since they included the county lines. Bad cartographer, no pizza.)

wedeliver · Post by **wedeliver** » Mon Sep 29, 2008 10:00 am

Here is info on the "event" which happened early this year and hit Wells, NV.

http://earthquake.usgs.gov/eqcenter/eqi ... 9/#summary

Also from that Stat's page I posted previously it shows the state, number of recorded quakes 3.5 or better and the percent of total, compiled from the years 1974 - 2003.

1. Alaska 12053 57.2 %
2. California 4895 23.2 %
3. Hawaii 1533 7.3 %
4. Nevada 778 3.7 %
5. Washington 424 2.0 %
6. Idaho 404 1.9 %
7. Wyoming 217 1.0 %
8. Montana 186 0.9 %
9. Utah 139 0.7 %
10. Oregon 73 0.3 %

Isotopia · Post by **Isotopia** » Mon Sep 29, 2008 2:16 pm

They say Alaska = #1, California = #2 and Hawaii and Nevada are essentially tied for #3

You're right. I should have noted second most active in the lower 48 states.

Sorry. My bad.

theCryptofishist · Post by **theCryptofishist** » Mon Sep 29, 2008 5:57 pm

It was nice to see everyone show off their geo-chops.

And the lower 48 thing did cross my mind. It was kind of nice to think it through.

Simon of the Playa · Post by **Simon of the Playa** » Tue Sep 30, 2008 6:02 am

i cant resist....the lead up was just too tasty...automatic pun response too strong....

so, did you feel the earth move too?

dr.placebo · Post by **dr.placebo** » Tue Sep 30, 2008 8:25 am

We just had another one out there, M 2.6. It's also listed as depth 0 km, which may mean that the depth estimator is broken, or that some damn fool had way too many spare sticks of dynomite.

wedeliver · Post by **wedeliver** » Tue Sep 30, 2008 8:40 am

This one is twice the distance away from Gerlach (30 miles NE of Gerlach). Even the first one was not on the Playa but east of Trego by 1 mile.

http://quake.usgs.gov/recenteqs/

The zero depth comes up quite a bit on the reports. I don't have any idea why, but if you go to the index and maybe check out recent events in the Geysers area, you will see a number at a zero depth.

chiefdanfox · Post by **chiefdanfox** » Tue Sep 30, 2008 8:58 am

dr.placebo wrote:We just had another one out there, M 2.6. It's also listed as depth 0 km, which may mean that the depth estimator is broken, or that some damn fool had way too many spare sticks of dynomite.

Maybe, but usually zero depth means there is no data from contributing networks or sensors. One sensor can measure magnitude locally, but we need a few sensors to triangulate the depth.

dr.placebo · Post by **dr.placebo** » Tue Sep 30, 2008 7:06 pm

You're right about the need for triangulation. The 2.6 has been upgraded to a 3.0, and at those magnitudes it is really unlikely to be a surface event. At really small local magnitudes in mining country there is a pretty good likelihood of the measurement being from an explosion.

Isotopia · Post by **Isotopia** » Tue Sep 30, 2008 8:54 pm

Note how the hypocenter is almost always adjacent to a series of ridges/mountains.

Slip block fault basin geology is a grand thing.

ygmir · Post by **ygmir** » Tue Sep 30, 2008 9:01 pm

I thought the great basin mountain ranges were compression ridges, and, the fault block/slip took place between the crest of the Sierra's and the central valley.........

RingO'Fire · Post by **RingO'Fire** » Wed Oct 01, 2008 10:56 am

chiefdanfox wrote:...many areas of the Basin and Range are collapsing much faster than that. The causes of the orogenic collapse are still a bit of a challenge to get folks to agree on, but the amount and speed are not really open to much interpretation.

I wasn't really aware of this - the collapsing of the Basin and Range. But after reading your post, I've done a little reading and feel somewhat conversant. I found a good abstract briefly summarizing the various theories here: http://www.geol.ucsb.edu/faculty/gans/a ... s1993.html

moesy · Post by **moesy** » Wed Oct 01, 2008 12:48 pm

May I say, Wow, Fascinating and Thank You!?

Isotopia · Post by **Isotopia** » Wed Oct 01, 2008 1:55 pm

Extension of the Basin and Range Province:

If you want to really have your mind blown consider this.

The Basin and Range province here in the west represents a spreading of a small portion of the North American plate. Many theories abound as to what drives it, what initiated it and what it represents for the continent during the next several eons is a garden ripe with informed, creative ideas and speculation. What we do know is that the a portion of the plate is spreading very slowly but quite predictably. To give you an idea of how much the plate has spread, consider the ~12 hour driving time from Reno to Provo, (or Salt Lake) Utah was once only a distance of ~2 hours of regular driving time.

BTW Ring-o-Fire, Elizabeth Miller the co-author of the paper you cited is a friend and past teacher of mine here at SU. She's probably one of the more well versed geologists in the world on B&R geology as she did her PhD paper on the Lake Lahontan basin. She's also a long time BM attendee who can ALWAYS be found at Martini Camp (~ 4:30 and middle ring.) The camp's a good group of people and she's usually ready to talk rock. You might look their camp up next year.

Look for her at Martini Camp (though I don't think there'll be a helicopter there.)

theCryptofishist · Post by **theCryptofishist** » Wed Oct 01, 2008 6:35 pm

Conversations containing the word "orogenic" are always cool.