Ouch, that’s gotta hurt…
I’ve been through a 7.2 and it’s not nice. Worse when the building codes are not so great and unreinforced masonry is a frequent building material.
Pakistan Centric View
Quakes Hemisphere Map centered on Pakistan
Original Map with Clickable areas for details
Magnitude 7.2 – SOUTHWESTERN PAKISTAN
This event has been reviewed by a seismologist.
Magnitude 7.2
Date-Time
Tuesday, January 18, 2011 at 20:23:26 UTC
Wednesday, January 19, 2011 at 01:23:26 AM at epicenter
Location 28.838°N, 63.947°E
Depth 84 km (52.2 miles) set by location program
Region SOUTHWESTERN PAKISTAN
Distances
45 km (30 miles) W of Dalbandin, Pakistan
260 km (160 miles) W of Kalat, Pakistan
310 km (190 miles) ESE of Zahedan, Iran
1035 km (640 miles) WSW of ISLAMABAD, Pakistan
Location Uncertainty
horizontal +/- 7.1 km (4.4 miles); depth fixed by location program
Parameters
NST=159, Nph=159, Dmin=>999 km, Rmss=1.33 sec, Gp= 47°,
M-type=teleseismic moment magnitude (Mw), Version=1
Source USGS NEIC (WDCS-D)
Event ID us2011ggbx
Interesting that it is a bit off the large fault line too. It’s as though there is one mode that is ‘fault slip’ that we’ve been in for most of my life and another that is ‘mountain building’ where the stresses are more away from the faults. As though the ‘skin’ is being pushed in everywhere rather than plates jostling for position. Yes, all just idle speculation…
Pakistan 7.2 18 January 2011
Both Hemispheres
A view of Earthquakes from the South Pole
Original Image with Clickable Details
North Polar Earthquake Map
Original Image with Clickable Details
North America
North America and Mid Atlantic Ridge Quake Map
Original with clickable details
Live USA Quake Map
Live USA Quake Map
California Map
Action Closer to Me
Current quake map in California
Original Image, with captions and description. The original is interactive with clickable regions for ‘close ups’.
In Conclusion
I’d expect there to be significant damage and loss of life from this. Mostly due to poverty not leading to great building codes. We’ll have to wait and see. With any luck, the government of Pakistan will have been more effective at making safety of construction an issue. ( Islam does lend itself to a greater tendency to grand buildings made solidly, we’ll have to see if that also translates to the general countryside and “tribal areas”.) This quake looks per the simple USGS map to be a non-urban area. I hope it is just a bunch of farm land with “stick built” houses.
(Sidebar: The common term here for 2 x 4 inch wooden wall stud construction is “stick built”. it does not mean ‘made from wattle and daub” nor actual sticks…)
Musings from the Chiefio 
Dalbandin seems to be the only town and it is 30 miles east of the quake. The rest of the area is almost vacant.
http://www.bbc.co.uk/news/world-south-asia-12222081
For some reason I have this image of thousands of sheep, struggling back to their feet, looking quisically at each other in a Wallace and Gromit way…
BAAAAA, BAaaaa, Baaaaaaaa, baa…
as the sheep dog wonders who knocked all the sheep down and why he didn’t see them bowl him over along the way…
Bin Wallace, sleeping under the only tree for 20 miles… semi-oblivious, asking “Is it time to get up already, give us a moment more… zzzz”
They have another word for contiguous????
I think the original slang name for houses built with 2×4 was ‘balloon houses’.
The ‘balloon-frame’ lacked the heavy timbers of European technique, and was thought to be as flimsy as a balloon.
http://www.uh.edu/engines/epi779.htm
One key element added later was ‘fireblocks’, initially ~non-structural horizontal pieces which spoil the ‘chimney effect’ otherwise present within the walls.
Fortuitously, they are quite good at riding out temblors gracefully, if they can stay in place on the foundation.
RR
@Ruhroh:
I think you are close, but that the “balloon” construction also is lacking in the major framing / sills that ARE present in the common ‘stick built’ of today. So the 2 x 6 and such members that often run round the top and bottom edges of the walls or are sometimes doubled 2 x 4s.
@PhilJourdan:
Sorry, but I’m not following you?…
Balloon frame is constructed by starting with a single sill plate to which tall studs were attached that ran to the single top plate. floor and ceiling joists were hung from the studs and rafters ran from the top plate to the ridge. The outside wooden skin was nailed to this as was the inside walls, floors and ceilings due to this balloon like construction, the space between the studs and joists, from foundations to the attic was open and in a fire these spaces acted like a chimney flue. A balloon frame house would explode into flame and collapse in minuets. These were generally built of rough cut pine, very cheap and fast construction.
My familys home, a 100 year old 2 story balloon frame, burned to the ground one afternoon when I was 15. Glad no one was inside.
Stick frame construction requires the completion of foundation to the floor joist and floor deck, then stud wall to a double top plate that the ceiling joist are attached on top of. Then the roof or next floor is set. Now days the ceiling joist and rafters are often built as one unit as a truss and “fire block” installed between studs to stiffen the walls. Originally fireblocking was added to balloon frame studs to prevent “chimney effect”and this was carried over to stick framing.
I should add that a balloon frame is quite strong in an earth quake as it is well tied together from sill to rafter and is very flexible. A stick frame is only held together with the shear and draw of the nails, is more ridged and in long quakes will fall apart. All must have good foundations that they are well connected to. pg
I had to look up the word conterminous – and I thought contiguous was all fancy and such!
Andrew Aklden at Andrew’s Geology Blog (http://geology.about.com/b/) discussed this as a deep-focus earthquake. “In general, rocks deeper than about 50 km aren’t supposed to be brittle enough to support quake-producing high stresses. But there are ways to get around that. The simplest is to pull cold lithosphere down deep, where it can fracture before it fully warms up. That seems to be the case for this event: the ongoing collision of India with Eurasia has pushed the lithosphere into a thick pile, and the rock at 80 km depth is still brittle.”
He also has a link to his lengthier description of the likely processes behind these kinds of earthquakes. One possibility: chemical changes from pressure and temperature increase with water released at each step making the slab/rock more compact and brittle. I enjoy his blog and he is a sensible geologist re AGW.
Looking at the California map, the earthquakes sure are lining up, one side going north to your digs, the other going north through Bishop-Mammoth and heading along the state line beyond Lake Tahoe. And then there is that crossover south of Bakersfield. Wonder if this portends something new and interesting. One thought (more likely just a musing) is further extension of the deep valley areas on the east as the Sierra mountain building smash-up relaxes (plate went down and east) I notice that the western part of NA is moving southwest, but the east coast seems to be moving northwest.
While kind of off topic for the specific EQ in Pakistan, I had something of an epiphany today in a different but related context.
While in a meeting discussing technologies “in the pipeline” relating to mobile communications, it was clear that people are going to be “connected” 24×7 no matter where they are. People’s “phones” are evolving into a pocket PC and people will be constantly connected and can communicate with nearly anyone in any number of ways instantly.
The problem comes in when we have a major disaster. That is an extremely stressful situation. The problem is that once people become used to being “connected” at all times, the combination of a disaster striking combined with everyone suddenly becoming disconnected will make the stress level even worse.
Even without a disaster, people would come to associate the disconnection of mobile communications itself as something of a disaster in and of itself once a generation “grows up” with that as the normal condition. People will become so reliant on that device in their pockets that they will probably be very disoriented, confused, and probably quite scared because they will experience themselves as completely “disconnected” from the virtual world they have created for themselves and have very little skill in dealing with people in a “real world” basis.
Rather than pooling in echo chambers of people who all share the same opinions, they will be faced with interacting people with pretty much random opinions, values, and beliefs. They will not have access to immediate up to date information. People are going to be upset enough, not being connected is going to drive them absolutely nuts.
@George:
Interesting psychological ideas. But even folk on the phone all the time have a fair degree of Real World interaction, plus the cell sites are made to be very quake proof. Then again, systems went out in Katrina…
But you have given me an idea for an iPhone App… Not sure how to impliment it, nor make money off of it. So I think I’ll just toss it out here:
The iPhone has GPS and it has an accellerometer. Enough of them that ‘sign up’ for a quake app would detect the P wave early, and could then ‘alert’ those further out that the P and S waves were ‘headed their way’. As a secondary part of the App, if cells start going ‘dark’ in area that just had a quake they could paint a size / strength map for the ‘concerned’ to see…
Something like this was proposed about 20 years ago, but the number of accellerometers needed and the ‘near instant notice’ needed for the ‘to be warned’ made it impractical. You “only” get a couple of minutes notice so folks would have had to be ‘standing by their phones’ all the time…
Things have changed now..
would need a bit of a cloud computing back end and a critical mass of folks signed up on the front end… plus some software to sort out the ‘daily commute rush’ on the L Train…
Better to put one in OnStar equipped cars. They already have them anyway.
Parked cars could be an interesting monitoring device.
One thing that is interesting: People’s cell phones won’t be working and there won’t be any public telephones either. They are all gone, because people use cell phones. I can’t remember the last time I saw a phone booth.
Back about 5 years ago, people used to drive out to the Mojave desert to take pictures of the one out there.
@George:
Not only do people find the darndest things to put here as links, someone ELSE has done the darndest things…
Who knew there even WAS a phone booth in the middle of nothing, nowhere…
Yeah, phone booths are going away… but not yet completely gone. Also, in disasters, don’t forget the HAM radio operators who come out of the woodwork…
I’m not one (yet, but I’m thinking about it), however, I can make a radio ‘from scratch’ (and have) so if things got really bad I suppose we could always do that (after a while…)
Though I don’t expect it will be needed. The cell sites are rated to some ungodly spec…
The problem with the cell sites is fuel. Getting the fuel to all the various towers when they have to get in line behind the hospitals, police, and fire might be difficult. Even more difficult if the roads are damaged or the fuel depot itself is damaged. That is going to be the major problem in a regional disaster such as a Hayward Fault break. It is going to be nearly impossible to obtain fuel and the “hardwire” phone central offices will likely be in line ahead of the cell sites.
NOTE that many are migrating to natural gas generators from diesel. If the gas infrastructure survives, they will be ok, but if that is disrupted, it is going to make it worse because there is little storage on site (maybe 24hrs).
Diesel storage is limited by law to 48hrs supply unless you get a special waiver. The idea there is to limit potential spillage in case of an accident so they limit the amount you can store. Now in the case of Silicon Valley, practically every data center in the valley is going to be scrambling for fuel immediately. If they don’t get any within 48 hours, they are going to start going dark. Same with any offices with backup generators.
If you want to make a mint in case of an emergency, have a large supply of diesel fuel in seismic hardened storage with a military style tanker for deliveries that can move off-road if required.
Whoever can deliver fuel under those conditions is going to rake it in. You can charge market rate for the fuel, but really stick it to them for the delivery, depending on conditions. Or you could have prospective customers bid on fuel with a “second item” auction process. So lets say your tanker holds 1,000 Gal of fuel. Let the bidders make their offers. Say bidder 1 offers $5/gal for 200 gal and bidder 2 offers $4/gal for 500 Gal, and bidder 3 offers $4.50/gal for 1000 gal. Bidder 1 gets 200gal for $4/gal, Bidder 2 gets 500gal for $4/gal and bidder 3 gets 300gal for $4/gal. If bidder 3 had beaten bidder 2 to the auction, he would have got 800 gal for $450 and bidder 1 gets his 200 and bidder 2 (who would then be bidder 3) would get none and has to wait to bid on the next tanker load.
That way you aren’t “price gouging”, you are letting the market decide the price.
How they would get their bids to you, I have no idea, there will probably be a run on old 11 meter CB radios.
I think you will have two problems with the idea of a ‘bid’ beyond just how to do it.
1) A business model that has a ‘payoff’ once every 100+ years is not very effective, even if the profit margin is high.
2) Governments like to make laws about price gouging and you are likely to find your buisness model broken on day 2.
But that thing about the 48 hour limit is a problem. It will take more than that to “fix things”…
20:23:26 UTC the moon …..
@Michele:
What a fascinating image. Where did you get it / who makes it?
(Like your name too ;-)
FWIW:
I find this one interesting as it is yet another quake off the plate boundary and more under the mountains. Note that this is INLAND Alaska:
Magnitude 5.1 – CENTRAL ALASKA
This event has been reviewed by a seismologist.Magnitude 5.1
Date-Time Sunday, January 23, 2011 at 02:50:04 UTC
Saturday, January 22, 2011 at 05:50:04 PM at epicenter
Time of Earthquake in other Time Zones
Location 63.576°N, 150.830°W
Depth 9.9 km (6.2 miles)
Region CENTRAL ALASKA
Distances 95 km (60 miles) WNW of Cantwell, Alaska
100 km (60 miles) WSW of Healy, Alaska
205 km (130 miles) SW of Fairbanks, Alaska
1065 km (660 miles) NW of JUNEAU, Alaska
Location Uncertainty horizontal +/- 11.6 km (7.2 miles); depth +/- 1.2 km (0.7 miles)
Parameters Nph= 0, Dmin=0 km, Rmss=0.83 sec, Gp= 97°,
M-type=body wave magnitude (Mb), Version=9
Source Alaska Earthquake Information Center, Fairbanks, USA
Event ID usc000180z
No faults showing on the close up map either:
http://earthquake.usgs.gov/earthquakes/recenteqsww/Maps/10/210_65.php
Same with that cluster in Nevada near Walker Lake. No fault near the quakes.
@George:
Hmmm… I’d missed that:
Magnitude 4.1 – NEVADA
This event has been reviewed by a seismologist.Magnitude 4.1
Date-Time Saturday, January 22, 2011 at 19:21:05 UTC
Saturday, January 22, 2011 at 11:21:05 AM at epicenter
Location 38.525°N, 118.406°W
Depth 6.9 km (4.3 miles)
Region NEVADA
Distances 19 km (12 miles) E (90°) from Hawthorne, NV
20 km (12 miles) W (276°) from Luning, NV
24 km (15 miles) SSW (203°) from Midway, NV
266 km (166 miles) E (90°) from Sacramento, CA
Location Uncertainty horizontal +/- 2.4 km (1.5 miles); depth +/- 2 km (1.2 miles)
Parameters NST= 19, Nph= 21, Dmin=15.4 km, Rmss=0.19 sec, Gp=187°,
M-type=local magnitude (ML), Version=7
Source Seismological Laboratory, University of Nevada, Reno
Event ID nn00325007
Strange. Very strange…
I’m back at that point of thinking there is a fault / slip-strike mode and a mountain building off the fault mode and the two are different from different drivers of the crustal motions. Perhaps one upwelling / mantle driven the other compressive / spin-orbit-couple driven…
Good grief. I have just finished watching a pretty ominous show. Basically the situation is this:
Southern San Andreas breaks pretty regularly every 200 years. It has been over 300 years since it last broke in that section. There is estimated something close to 30 feet of ground slip movement potential in the locked portion of the fault.
The straight portion of the fault points directly toward LA though the fault takes a turn before it gets there. If the fault breaks South to North, the shock wave and the shaking from the break will head directly into LA.
According to the show (quoting USGS) there is a 99% chance of this section of the fault breaking over the next 30 years.
All that said, there is another somewhat ominous situation in that the curved section around Ft. Tejon has been over 150 years since it last broke. We could be setting up for a situation where the fault breaks from the Salton Sea all the way up to Parkfield through the Ft. Tejon section.
When the Southern section breaks, it is going to be a bad day for the “Inland Empire” and if the Tejon section breaks, Katy, bar the door. It is going to be a bad day all the way up through the Grapevine.
Yes, I have been seeing lots of compression and little slip yet. The Parkfield to L.A. fault is very quiet. The area where it crosses the Tehachapis has started to crack a bit. 30 feet of movement could be very exciting, even with California building codes. 8-] pg
Yup. George, that about sums it up.
Do not under any circumstances buy property nor live in downtown LA and think very seriously before working there. I will take SHORT duration contracts (i.e. days or weeks) but not years… and even then I’d give the building a ‘once over’ before accepting.
My “nightmare scenario” is that the South LA part goes, that gets ‘focused” through LA, then causes the “bent part” to go. All of that hit’s up here and kicks the Clavaeras / Hayward system into a sympathetic 7.x and we’ve bacically fried the whole state.
Not likely as they are likely to go at different times. But nothing really preventing it… The good news is that due to where I am I’d likely come through it OK. The bad news is that I’d be surrounded by disaster area in all directions.
Well, “sweet dreams” ;-)
(but at least now you know why I always have a California Quake page somewhere I can check easy…)
The only saving grace would be if the fault broke initially at the Northern end and the shear traveled South. That would point the “Megashear” out into desert.
Oh, and what the show I was watching didn’t mention was how the Landers/Big Bear event (two separate quakes on the same day) might have changed the stress on the San Andreas. That was a pretty big quake and I happened to be in Riverside that morning. Both quakes seemed equally strong from where I was because the Big Bear event was much closer.
Then there was the Hector Mine event shortly after.
Both Landers and Hector Mine were 7+ events. The recurrence interval in that area is measured in thousands of years rather than hundreds so maybe it only slips when the Southern end of the SAFZ gets “stuck”.
Oh, and one final thing. They had a pretty good explanation for why they thought there were no large quakes in the “creeping section” of the fault South of San Juan Bautista. Apparently those rocks are full of talc. The talc is both very weak and acts as a lubricant. The more talc in the rock, the more likely the fault is to break at low levels of stress or to keep sliding without breaking at all.
This information came from core samples taken directly through the fault at about a 2km depth. The rocks showed a significant content of talc and serpentinite which gets morphed into talc. I also found this reference in Nature:
http://www.nature.com/nature/journal/v448/n7155/abs/nature06064.html
And looking for that, lead me to this:
http://shearsensibility.blogspot.com/2007/08/talc-and-weak-fault-problem.html
The notion is that the “creeping” section of the fault probably has a higher concentration of talc than the parts that tend to “stick”.
@ George on 25 January 2011 at 8:18 am
Not if you live in the desert.
True, but as the population in the desert is smaller by orders of magnitude, the cost of damage measured in both human and financial terms would seem to be lower.
Agreed – however calling it a “saving grace” when your loved ones are part of the “smaller by orders of magnitude” is not comforting.
@George:
So you are saying we need to put talcum powder on the crack to keep bad things from making a mess? ;-)
Wonder how hard it would be to do ‘talc slurry’ injections into a fault system….
And Baja gets another 4.2 sized….
Not all that interesting to the rest of the world but that’s where my fault starts getting it’s mojo so I like to know what it’s up to.
Magnitude 4.2 – BAJA CALIFORNIA, MEXICO
This event has been reviewed by a seismologist.Magnitude 4.2
Date-Time Wednesday, January 26, 2011 at 00:11:28 UTC
Tuesday, January 25, 2011 at 04:11:28 PM at epicenter
Location 31.226°N, 115.685°W
Depth 10 km (6.2 miles) (poorly constrained)
Region BAJA CALIFORNIA, MEXICO
Distances 21 km (13 miles) SSE (166°) from L�zaro C�rdenas, Baja California, Mexico
59 km (37 miles) NNE (31°) from Vicente Guerrero, Baja California, Mexico
82 km (51 miles) WNW (288°) from San Felipe, Baja California, Mexico
114 km (71 miles) SE (129°) from Ensenada, Baja California, Mexico
192 km (119 miles) SE (139°) from Tijuana, Baja California, Mexico
Location Uncertainty horizontal +/- 2 km (1.2 miles); depth +/- 31.6 km (19.6 miles)
Parameters Nph= 17, Dmin=29 km, Rmss=0.33 sec, Gp=191°,
M-type=local magnitude (ML), Version=4
Source California Integrated Seismic Net:
USGS Caltech CGS UCB UCSD UNR
Event ID ci14922580
But if I’m going to mention it, I probably ought to mention that Alaska is moving too:
Magnitude 5.3 – ANDREANOF ISLANDS, ALEUTIAN IS., ALASKA
This event has been reviewed by a seismologist.Magnitude 5.3
Date-Time Tuesday, January 25, 2011 at 07:46:34 UTC
Monday, January 24, 2011 at 09:46:34 PM at epicenter
Time of Earthquake in other Time Zones
Location 51.632°N, 176.199°W
Depth 57.3 km (35.6 miles)
Region ANDREANOF ISLANDS, ALEUTIAN IS., ALASKA
Distances 40 km (25 miles) SE of Adak, Alaska
135 km (85 miles) E of Tanaga Volcano, Alaska
1920 km (1200 miles) WSW of Anchorage, Alaska
2730 km (1700 miles) W of JUNEAU, Alaska
Location Uncertainty horizontal +/- 16.4 km (10.2 miles); depth +/- 0.3 km (0.2 miles)
Parameters NST=391, Nph=411, Dmin=52.3 km, Rmss=0.84 sec, Gp= 79°,
M-type=body wave magnitude (Mb), Version=9
Source USGS NEIC (WDCS-D)
Event ID usc00018tl
Both ends moving and I’m in the middle… just glad it’s far away. For now.
Those quakes have more to do with the spreading center from the old Farallon/Pacific plate boundary than the San Andreas fault.
@ E.M. “Wonder how hard it would be to do ‘talc slurry’ injections into a fault system….”
I am guessing that you are well aware that has been considered.
Here is one very brief summary analysis (taken from http://www.stockton.edu/~hozikm/geol/Courses/Structure/Lectures/Earthquakes%20and%20Fluid%20Pressure.doc)
Begin quote:
A Daring Suggestion
• Control earthquakes on the San Andreas
– Drill a series of wells
– Pump water out of A & C to lower fluid pressure and lock the fault
– Pump water into B to trigger earthquakes
– Pump water out of B and D to lock the fault
– Pump water into C to trigger earthquakes
– Repeat along the fault
Analysis
• Earthquakes should be smaller than M = 4.5
– This requires a depth of 5 km and a slip rate of 2 cm/yr
– Wells would be drilled 5 km apart and 5 km deep
• Cost
– Need about 70 wells
– Each well is 5 km deep
– Drilling costs ~$100/foot x 1700 ft per well
– 1.7 x 106 per well x 70 wells = $120,000,000 just to drill
Analysis
• Total cost is high and will be hard to sell
• Pumping needs to be repeated every six months
• It is risky
• It may take a prohibitively large number of small earthquakes to prevent a big one
• This is still in the dreaming stages, but it is an interesting idea
• May be worthwhile at site of large dam or other proposed project
: End quote
@Jason Cally:
I knew about the water injection, not the talc. FWIW I was in a modest quake near Lake Oroville shortly after they filled the lake behind the dam. Attributed to the water weight (and potentially some water lube…)
Was thinking that if you lightened the load with small ones (or started injection just AFTER a big one ;-)
then a talc slurry lube would prevent future ones…
Of course, there IS that small problem of lubing the fault in your country so all the energy moves through faster to the next door country who is in a world of hurt if THEY are not lubing their fault ;-)
FWIW, a 6.1 in Indonesia… (Remember a couple of years ago when we would go weeks to months without a 6 to 7 range quake?…)
Magnitude 6.1 – SIMEULUE, INDONESIA
This event has been reviewed by a seismologist.Magnitude 6.1
Date-Time Wednesday, January 26, 2011 at 15:42:29 UTC
Wednesday, January 26, 2011 at 10:42:29 PM at epicenter
Time of Earthquake in other Time Zones
Location 2.120°N, 96.741°E
Depth 26.8 km (16.7 miles)
Region SIMEULUE, INDONESIA
Distances 230 km (145 miles) W of Sibolga, Sumatra, Indonesia
270 km (165 miles) SW of Medan, Sumatra, Indonesia
565 km (350 miles) WSW of KUALA LUMPUR, Malaysia
1440 km (900 miles) NW of JAKARTA, Java, Indonesia
Location Uncertainty horizontal +/- 15.9 km (9.9 miles); depth +/- 1.7 km (1.1 miles)
Parameters NST= 70, Nph= 73, Dmin=129.1 km, Rmss=1.7 sec, Gp= 65°,
M-type=”moment” magnitude from initial P wave (tsuboi method) (Mi/Mwp), Version=6
Source USGS NEIC (WDCS-D)
Event ID usc000197d
“(Remember a couple of years ago when we would go weeks to months without a 6 to 7 range quake?…)”
Since the 2005 subduction zone quake, we are probably going to get more as the rest of that subduction zone reacts to the change. At some point we will also get some additional volcanoes (which we are already seeing evidence of) as some several dozen feet of sea floor was subducted. It will take a while for it to all get melted and heated up, but when it does, watch out!
@George:
Thanks for the pointer at the Farallon Plate. Never heard of it before (as it seems it is an historical thing…)
A bit of looking showed what you said, that the belief is that the spreading zone of that plate has been subducted under North America.
But that does not ease my worry…
It’s that “spreading” which is sending the Gulf of California up into the Salton Sea and on to Death Valley and directed past that toward Mammoth Lakes Caldera…
Yes, it ought to take millions of years to get there, but along the way there will be a lot of “action”.
So yes, you are right, it’s not so likely that it’s going to run up the San Andreas (other than as a spreading artifact) and yet the alternative isn’t a whole lot more pleasing…
Then notice that the “spreading” is coincident with the fault all through the Gulf of California and up into the California / Baja join and only well inland divides and has the San Andreas go one way and the ‘rest of it’ head toward Mammoth… and I’m beginning to suspect that the SAF has a mite more connection to the “spreading” than I’d care to think about right now. Lord Knows something is driving it to move…
Well, a 6.0 in the same region and a bit of action near Cascadia…
Magnitude 6.0 – SOUTHEASTERN IRAN
This event has been reviewed by a seismologist.Magnitude 6.0
Date-Time Thursday, January 27, 2011 at 08:38:28 UTC
Thursday, January 27, 2011 at 12:08:28 PM at epicenter
Time of Earthquake in other Time Zones
Location 28.185°N, 58.968°E
Depth 10.7 km (6.6 miles) set by location program
Region SOUTHEASTERN IRAN
Distances 120 km (75 miles) SSE of Bam, Iran
200 km (125 miles) WNW of Iranshahr, Iran
235 km (145 miles) SW of Zahedan, Iran
1095 km (680 miles) SE of TEHRAN, Iran
Location Uncertainty horizontal +/- 14.6 km (9.1 miles); depth fixed by location program
Parameters NST=213, Nph=217, Dmin=453.1 km, Rmss=1.56 sec, Gp= 25°,
M-type=teleseismic moment magnitude (Mw), Version=C
Source USGS NEIC (WDCS-D)
Event ID usc00019jy
This one is nicely off shore at the area of lesser concern, but it still fits that pattern of more crustal motion, more quakes, more volcanoes…
Magnitude 4.1 – OFF THE COAST OF OREGON
This event has been reviewed by a seismologist.Magnitude 4.1
Date-Time Thursday, January 27, 2011 at 13:02:41 UTC
Thursday, January 27, 2011 at 05:02:41 AM at epicenter
Time of Earthquake in other Time Zones
Location 43.707°N, 127.432°W
Depth 10 km (6.2 miles)
Region OFF THE COAST OF OREGON
Distances 265 km (165 miles) W of Coos Bay, Oregon
290 km (180 miles) WSW of Newport, Oregon
315 km (195 miles) NW of Brookings, Oregon
375 km (235 miles) WSW of SALEM, Oregon
Location Uncertainty horizontal +/- 24.9 km (15.5 miles); depth +/- 0.4 km (0.2 miles)
Parameters NST= 48, Nph= 48, Dmin=310.6 km, Rmss=1.02 sec, Gp=238°,
M-type=body wave magnitude (Mb), Version=6
Source USGS NEIC (WDCS-D)
Event ID usc00019kx
And that California map has a nice line of clear activity running up the Hayward / Calaveras system. Id bet money was going to go ‘soon’ but in geologic time scales that could be a decade or two and you just end up bickering over when ‘soon’ ends ;-)
SAF is a pure “stike-slip” thing but one should put it in context.
If you imagine North America as rotating counter-clockwise and the Pacific plate moving North, the Western edge of the North American plate is being pushed over on top of the Pacific plate along the California coast. The Pacific does subduct under the North American up in Alaska, but not down here. Here there is a conveyor belt moving North with material being pushed onto it from the East.
What happens is that at a weak point someplace, the material being pushed onto that conveyor belt cracks and starts to ride North. As time goes by, as more material gets pushed onto that conveyor belt, the place where that crack forms moves East. So we see the San Gregorio fault that now runs through Monterey Bay and just offshore. If you follow that fault South you will find the San Simeon fault after a break without any surface expression. Then that whole fault system gets quite complex down around the Santa Ynez fault. But the one thing in common is that they haven’t been active in a very long time.
Just East of that fault zone is the Rinconada fault which sort of morphs into the Reliz fault as you trace it North.
Now looking East of San Andreas up in the Bay area we see Calaveras, Hayward, the Hayward apparently continuing up to the Rodgers Creek and that whole thing seeming to point continuing North to the Maacama.
East of that isn’t much. At that point the North American material is pretty thick. The Pacific plate extends under the North American to almost to the Sierras. There was a subducted spreading center there but the Farallon side simply fell away into the mantle.
Actually, a better way of looking at it is that the North American plate has been pushed over on top of the Pacific almost as far East as the Sierra but the San Andreas, if you were to slice California across the short axis, would be diagonal going down and to the right (East) and there are a lot of new and old “cracks”. Imagine having a slow moving conveyor and slowly pushing a slab of cheddar cheese onto it. It will begin to bend and then crack. It will crack in several places but as you keep pushing the cheese onto the conveyor, the place where the cracking is happening moves East.
There is probably also a “blob” of partially melted material that detached from the Farallon that is just sort of hanging there in the mantle under the basin and range region. Farallon plate material would be heavier (mostly basalt) than the granites of North American.
Some interesting reference links:
http://www.jsg.utexas.edu/news/feats/2008/xray_vision.html
http://www.physorg.com/news/2010-12-ancient-raindrops-reveal-mountains-south.html
http://magmacumlaude.blogspot.com/2008/05/accretionary-wedge-9-cenozoic-magmatism.html
Click to access Liu01tectono.pdf
Interesting stuff….
Though I have to point out that my “view” of thins is colored by having grown up about 90 miles from Lassen…
So to me, the N. California part is right near an active volcano (errupted in 1914? 15?) and that implies some active subduction still…
Yeah, I’ve moved a couple of hundred miles south since then. Which is darned near nothing…
So for So.Cal your description is very apt. For Eureka-Asland maybe a bit more subduction aspect needed. For in between… i;ll comment after the next great quake / volcano ;-)
Northern California north of Mendocino is different. If you follow the San Andreas North, it makes a hard left turn at about Petrolia. North of that point is the Gorda plate. That plate IS subducting under the North American plate and is the source of the material for the Cascades down to Shasta and Lassen. That is what remains of the Farallon place The Southern portion of the Northern Farallon plate is called the Gorda plate. The Northern part is called the Juan de Fuca Platen but they are actually different regions of the same plate … the remnant of the Farallon that is still subducting under North America. There is a portion still subducting under South America, too, but the central section is gone.
Actually, the wiki covers this one fairly well:
http://en.wikipedia.org/wiki/Gorda_Plate
See if this simulation comes through. A 7.8 starting on the eastern side of the salton sea. The shockwaves are shown spreading into the LA basin. I live to the east of Temecula with a 5,500 mountain somewhat shielding me, although to a lesser degree if the break occurs further south closer to the US / Mexico border.
http://earthquake.usgs.gov/regional/nca/simulations/animation.php?mov=ShakeOut_mapview_lowres&set=shakeout
Wow, looks like the Redlands, Riverside, San Bernardino, Moreno Valley, Ontario area gets hammered pretty hard.
Not to mention places like Banning. It will certainly be a mess. Thing is, though, that the Landers and Hector Mine quakes might have allowed the East side of the SAFZ to slip a little bit North and relieve some of the pressure. So it might be another hundred years or so, nobody knows.
Hmmm…. Generally pretty quiet expect for a 6.2 in the Solomon’s and that 4 on the Baja / California border…
Magnitude 6.2 – SOLOMON ISLANDS
seismologist.Magnitude 6.2
Date-Time Monday, February 07, 2011 at 19:53:42 UTC
Tuesday, February 08, 2011 at 06:53:42 AM at epicenter
Time of Earthquake in other Time Zones
Location 7.157°S, 155.284°E
Depth 413.9 km (257.2 miles)
Region SOLOMON ISLANDS
Distances 110 km (65 miles) SSW of Arawa, Bougainville, PNG
150 km (95 miles) WSW of Chirovanga, Choiseul, Solomon Islands
930 km (580 miles) ENE of PORT MORESBY, Papua New Guinea
2265 km (1400 miles) N of BRISBANE, Queensland, Australia
Location Uncertainty horizontal +/- 14.5 km (9.0 miles); depth +/- 5.3 km (3.3 miles)
Parameters NST=116, Nph=116, Dmin=476.4 km, Rmss=0.99 sec, Gp= 32°,
M-type=”moment” magnitude from initial P wave (tsuboi method) (Mi/Mwp), Version=8
Source USGS NEIC (WDCS-D)
Event ID usb0001a1z
Magnitude 4.0 – SOUTHERN CALIFORNIA
This event has been reviewed by a seismologist.Magnitude 4.0
Date-Time Sunday, February 06, 2011 at 23:56:00 UTC
Sunday, February 06, 2011 at 03:56:00 PM at epicenter
Time of Earthquake in other Time Zones
Location 32.647°N, 115.919°W
Depth 15 km (9.3 miles)
Region SOUTHERN CALIFORNIA
Distances 13 km (8 miles) SE (145°) from Ocotillo, CA
26 km (16 miles) E (83°) from Jacumba Hot Springs, CA
27 km (17 miles) SW (233°) from Seeley, CA
37 km (23 miles) WSW (245°) from El Centro, CA
42 km (26 miles) W (269°) from Mexicali, Baja California, Mexico
104 km (65 miles) E (83°) from Tijuana, Baja California, Mexico
Location Uncertainty horizontal +/- 0.6 km (0.4 miles); depth +/- 0.5 km (0.3 miles)
Parameters Nph= 71, Dmin=0 km, Rmss=0.41 sec, Gp=130°,
M-type=local magnitude (ML), Version=5
Source California Integrated Seismic Net:
USGS Caltech CGS UCB UCSD UNR
Event ID ci14930844
And we’re 39% or so of “Full” per the Google Moon Phase:
http://www.google.com/ig/adde?moduleurl=www.calculatorcat.com/gmodules/current_moon.xml&mkhp=1&source=moha&utm_source=en-ha-na-us-sk&utm_medium=ha&utm_term=moon%20phase
So in about 2 weeks…
Hmm looks like the Cascadia might be working it self up:
First there was a 4.7 last night:
Followed by a 5.2 this afternoon:
The quakes are within 40 miles of each other and at roughly the same depth (10.2 and 10.1 km). They might be preshocks or the the 5.2 was the “event” with the 4.7 as the precursor.