[dolanbaker]

Seems there are more and more strong earthquakes and volcanoes eruptions. Or is it usual?

Quite normal, in the random way these events happen, it's just that we see more of them because of better monitoring.

[dinopello]

In England when they got some unusual earthquake, they banned fracking.

[Timo]

In England when they got some unusual earthquake, they banned fracking.

What the frack???

But somewhat more seriously, being a lay scientist/geologist type who simply learns by reading v any formal training (I know. That may disqualify any opinion i might have.), simple common sense tells me that the earth, through its several hundred million year development has achieved a structural density, encapsulating all types of matter and gasses through the magic of gravity. When we drill down into the surface of the earth, pump in fluids (toxic or not) and extract gas, this action changes the density of the earths crust and the force of gravity readjusts to compensate. As i said, i am no scientist, so maybe i have this mental picture wrong in my head, but we are all flat out wrong in thinking that we can manipulate or ignore the simple laws of physics on such a monumental scale without any unpleasant consequences. I think it's well time that humanity start employing cost benefit ratios in all status quo operations. Benefits cannot be measured in simple economic terms, either. That's like saying that assisted suicide is justified because it provides jobs for enablers. Making this planet uninhabitable is justified because it employs billions of people. What other species of life on this planet thinks in this fashion? We are created in God's image? I think not.

[dinopello]

Making this planet uninhabitable is justified because it employs billions of people. What other species of life on this planet thinks in this fashion? We are created in God's image? I think not.

Didn't God flood the Earth, wiping out everything, save for one ark-full - all for political reasons (His numbers weren't high enough for His satisfaction in the most recent polls)?

[rangerone314]

Making this planet uninhabitable is justified because it employs billions of people. What other species of life on this planet thinks in this fashion? We are created in God's image? I think not.

Didn't God flood the Earth, wiping out everything, save for one ark-full - all for political reasons (His numbers weren't high enough for His satisfaction in the most recent polls)?

I guess we should all be glad that Obama only THINKS that he's God.

[Ferretlover]

Peru got shaken (not stirred) today, too. There are lots of places to follow earthquakes, one of them being: http://earthquake-report.com/

Earthquakes list August 24, 2011
Not dangerous : Fiji, Papua New Guinea, Indonesia, Japan(aftershocks), Virginia
Earthquakes list August 23, 2011
Very dangerous : United States (Virginia)
Moderately dangerous : INDONESIA, COLORADO
Not dangerous : Japan (aftershocks), Fiji Islands, Kashmir India border, Sandwich Islands, Guatemala, USA (Colorado), Japan (Hokkaido), Colombia, Papua New Guinea
Earthquakes list August 22, 2011
Moderately dangerous : INDONESIA (Sumatra), USA (Colorado)
Not dangerous : Indonesia, New Zealand, Japan( aftershocks), Japan ( Hokkaido), Vanuatu, Greece, Tajikistan, Saint Martin / Leeward Islands, Alaska, USA (Colorado)
Earthquakes list August 21, 2011
Very dangerous : VANUATU
Not dangerous : Indonesia, Japan (aftershocks), Vanuatu (aftershocks), Solomon islands, United States, Russia (Kamchatka), Greece, Chile, Turkey, South Sandwich Islands, Papua New Guinea, New Zealand, Georgia, France

What would be interesting to know is the frequency of earthquakes around drilling sites as opposed to non-drilling sites.

[dohboi]

It's hard for me to believe that any amount of drilling or mining could set off an earthquake that shakes the whole eastern seaboard.

[the48thronin]

In England when they got some unusual earthquake, they banned fracking.

What the frack???

But somewhat more seriously, being a lay scientist/geologist type who simply learns by reading v any formal training (I know. That may disqualify any opinion i might have.), simple common sense tells me that the earth, through its several hundred million year development has achieved a structural density, encapsulating all types of matter and gasses through the magic of gravity. When we drill down into the surface of the earth, pump in fluids (toxic or not) and extract gas, this action changes the density of the earths crust and the force of gravity readjusts to compensate. As i said, i am no scientist, so maybe i have this mental picture wrong in my head, but we are all flat out wrong in thinking that we can manipulate or ignore the simple laws of physics on such a monumental scale without any unpleasant consequences. I think it's well time that humanity start employing cost benefit ratios in all status quo operations. Benefits cannot be measured in simple economic terms, either. That's like saying that assisted suicide is justified because it provides jobs for enablers. Making this planet uninhabitable is justified because it employs billions of people. What other species of life on this planet thinks in this fashion? We are created in God's image? I think not.

You do understand that when they pump or allow gas to go out, they replace it with sand and water right? OH they pump water into oil fields also to help keep the oil going to the extraction wells, they inject elswhere...

[dohboi]

Here's a somewhat broader perspective.

http://www.scientificamerican.com/article.cfm?id=are-larger-earthquakes-a-sign

It seems that some seismologists, at least, think that clusters of large earthquakes may be more than statistical flukes. I would think that large-ish earthquakes in otherwise non-earthquake prone locations might raise the same questions.

No seismologist is likely to stand up and say--"Hey, even though it is statistically extremely unlikely for these things to happen at the same time, our models for how these things happen don't give us any mechanism for them to be related, so that's what we have to tell you. The fact is, we really don't know."

From the article:

the probability of another quake of magnitude 9 or larger striking in the next 6 years is about 63 per cent. "There's now an increased hazard situation for these very large earthquakes," he notes.

So this suggests that large quakes can increase likelihood of other large quakes in completely different areas of the world over times spans of six years.

But then at the end of the article we get:

stress redistribution to nearby faults after a major quake is limited to distances from the epicentre no more than two or three times the length ruptured by the original quake. That, says Parsons, means that even megaquakes shouldn't trigger large quakes more than a couple of thousand kilometres away.

So which is it, boys.

It seems to me that you could say that there may be some other shift or influence that we don't know about causing two quakes, rather than saying that one quake caused another. What that force could be--I haven't much of a clue.

[ritter]

So which is it, boys.

I don't think we'll ever be able to predict earthquakes in any meaningful way. The fact is, we on the west coast are overdue for a big one, statistically speaking. So, preparation is about as good as it gets for mitigating the affects.

[rockdoc123]

So this suggests that large quakes can increase likelihood of other large quakes in completely different areas of the world over times spans of six years.

No it does not. There is no way without breaking every last rule of rock mechanics that you can have quakes redistribute stresses over those distances. Within a single plate boundary it is highly unlikely you would see any effects beyond a few hundred km. The idea of thousands of km is incredibly naïve (not sure where this fellow got his degree). If this were the case you could feel the effects of a earthquake in say Seattle somewhere in Kansas. At best you might feel its effects in central Washington state. To propose that crustal quakes can somehow redistribute stresses across plate boundaries shows a healthy lack of understanding of earth science. When the thought of earth quake swarms is talked about what it means is in a given area once the initial failure takes place there is a immediate stress drop and a slight reorientation of the stress field such that pre-existing faults which were previously not in a failure position are oriented with respect to the stress field such that movement can occur. This understanding of fault behavior comes mostly from studies around San Andreas but the swarms are limited in distance to tens of km not thousands. Once the stress has been relieved the earthquakes stop and do not occur again until the stress builds up to the failure of yield point once again.

It seems to me that you could say that there may be some other shift or influence that we don't know about causing two quakes, rather than saying that one quake caused another. What that force could be--I haven't much of a clue.

Obviously you don’t but it is well known science amoungst structural geologists. There is not some magic unknown as you speculate, the mechanics behind earth quakes in general is well understood. What causes interplate earthquakes is almost certainly movement of some amount along pre-existing failure planes (and this includes the reactivation of faults as a result of upward welling magma in Yellowstone). Earthquakes happen in “stable” continental crustal areas all of the time. In southern Alberta there is the occasional shaking that goes on and has been linked to slight movement along fault planes that were formed during the Tertiary emplacement of the Rocky Mtn fold and thrust belt. In the eastern US the surface geology may look more or less benign but the area was subject to the same deformation as the Rockies back during the Taconic orogeny. It is generally those old fault planes that can be reactivated which will occasionally create earthquakes as intraplate stresses build up. Crustal plates are not free of intraplate stress. The fact that there aren’t more earthquakes is that the stresses are generally smaller than you find at plate boundaries (eg: San Andreas) or near mantle plumes (eg: Yellowstone) and can be dissipated gradually by motion along small fault planes that might be assisted by high pore fluid pressures.

simple common sense tells me that the earth, through its several hundred million year development has achieved a structural density, encapsulating all types of matter and gasses through the magic of gravity. When we drill down into the surface of the earth, pump in fluids (toxic or not) and extract gas, this action changes the density of the earths crust and the force of gravity readjusts to compensate. As i said, i am no scientist, so maybe i have this mental picture wrong in my head, but we are all flat out wrong in thinking that we can manipulate or ignore the simple laws of physics on such a monumental scale without any unpleasant consequences.

Psuedo-science I’m afraid. When a borehole is drilled into formations there are few changes to the surrounding rock under normal drilling conditions. To avoid “blowouts” wells are drilled with drilling fluids containing salts and barite such that the weight of the drilling fluid is equal or slightly higher to the fluid pressure of formation waters/brines/ hydrocarbons. Under certain circumstances wells may be drilled under pressured but integrity is still maintained and even if it isn’t formation fluids would only be produced until such time as pressures were balanced. When fracing formations are isolated (casing annular cement, packers, select casing perforations) and fluid pressure is increased to the point at which yield stress of the rock is reached and it fractures. As someone mentioned here sand or silicon beads are often used as propents so that the maximum length of fracture can be maintained (i.e. when a fracture happens due to high pore fluid pressure the stress drops immediately and the fracture closes unless propped). In almost all cases the maximum length of an induced fracture is 100 m into the formation. With a typical seven stage frac you might have a number of 100 m length fractures extending into the formation over a lateral distance of up to a kilometer (dependant on how long the horizontal section of the well is). The only possible issue that could happen is if there are pre-existing fault planes intersected by the well bore fluids could escape along them. Note that once the frac is completed the formation is back under the exact same boundary conditions it was in prior to drilling. So there is no change to rock density or the earths gravitational field or anything else weird that happens.

there is currently no way of predicting earthquakes in advance. Scientists have been working on this for many decades. I knew two of them who were working through the Center for Tectonophysics Research at Texas A&M. They have looked at all aspects including animal responses, magnetic etc. The issue is that although the mechanisms that drive earthquakes are well known and well understood it is impossible to know exactly what sort of stress relief mechanisms are happening in the subsurface. As an example sub-seismic movement along adjacent microfaults can completely relieve stress on larger problematic faults. Fluid pressure can change in a given system for all sorts of reasons which can either increase or decrease the likelihood of an earthquake dependant on how much and where. A given fault might be subject to stick-slip behavior at one time (this can create very large earthquakes) and then after an earthquake the fault plane perturbations that create the stick slip behavior might have been removed.

[dohboi]

Thanks for the insights, roc.

So you don't find it even a tiny bit strange that two major quakes happened on the same day in areas that hadn't seen anything close to that level of activity for over a hundred years in one case and fifty years in the other?

It doesn't strike you as a tad statistically improbable that the two are unrelated?

I know, and said as much, that the current level of our understanding of seismology seems to say that these can't be related. You affirmed this understanding. At some point, though, scientists have to re-examine their assumptions if 'coincidences' happen that their current theories can't account for.

"Fluid pressure can change in a given system for all sorts of reasons"

What kinds of reasons are relatively well known?

[rockdoc123]

So you don't find it even a tiny bit strange that two major quakes happened on the same day in areas that hadn't seen anything close to that level of activity for over a hundred years in one case and fifty years in the other?

absolutely not. The very nature of statistics related to naturally occurring events is that something titled a hundred year event may actually not happen for 2 hundred years and then happen twice within a year. If you bothered to look at the USGS earthquake site you'd see that this particular area is on its "high risk" for an earthquake event map. In the late 1800's the area was hit by several significant earthquakes. Because the bedrock layers here are older and hence highly compacted they tend to transmit shock waves more efficiently, hence a minor fault movement can create a significant earthquake that can do significant damage.

It doesn't strike you as a tad statistically improbable that the two are unrelated?

There are literally thousands of things that could be "statistically" related.
An example would be
With a decrease in the number of pirates, there has been an increase in global temperature over the same period.
Therefore, global temperature increase is caused by a lack of pirates

Statistics are only useful when taken into the context of the underlying science. The science related to earthquakes is very well understood.

"Fluid pressure can change in a given system for all sorts of reasons"

-compaction of sediments
-cementation of sediments
-maturation of hydrocarbons
-migration of hydrocarbons
-groundwater seepage
-changes in groundwater movements
-fault displacement (seismic or aseismic)
-surface geomorphologic changes (eg. slumping, solifluction, land slides etc)
-surface saturation (heavy rains, flooding etc)

[Outcast_Searcher]

It's hard for me to believe that any amount of drilling or mining could set off an earthquake that shakes the whole eastern seaboard.

+1

All one has to do is ponder just a LITTLE the kinds of forces building up in the tectonic plates that cause earthquakes in the real world. You know, the forces that build things like MOUNTAIN RANGES and giant OCEANIC TRENCHES.

But, no. Let's have two minor earthquakes in the US in one day, and all the sudden it's due to a bit of drilling. When we've been drilling and blasting giant caverns/mines with massive amounts of explosives for many decades without causing meaningful earthquakes. (i.e. Salt mines, copper mines, gold mines, coal mines, etc. Any of the scale of such activity ring a bell here?

Worrying whether hydrocarbons are seeping into water, and whether NG or shale oil fracking companioes are trying to cover it up is a rational pursuit -- and well worth investigating and ensuring there is proper regulation to ensure safety.

Blaming major (magnitude or scope) earthquakes on fracking without a HELL of a lot of convincing data is NOT rational -- given the forces the well developed science of plate tectonics tells us are behind earthquakes.

[dohboi]

Thanks for the +1 oc, and for the clarifications, rd. So above-ground factors (flooding...) can have an affect on earthquakes. I wonder if the unusually large rains they have been having in the East could have played a roll, then. And perhaps also the drought and heat in the west?

[Outcast_Searcher]

Thanks for the +1 oc, and for the clarifications, rd. So above-ground factors (flooding...) can have an affect on earthquakes. I wonder if the unusually large rains they have been having in the East could have played a roll, then. And perhaps also the drought and heat in the west?

I suppose that is possible. Not being a geologist, I can't comment intelligently. It isn't intuitive to me, but it can't be ruled out offhand without sufficient evidence. I'm guessing we don't have the science/tools yet to weigh such relative subtleties compared to plate tectonics relative to earthquakes.

After all, we are absolutely terrible at predicting earthquakes (aside from being able to say they will happen in certain areas periodically, and at VERY ROUGH (multi-decade) guesses, based on historical major quake frequencies.

Better than nothing but nothing CLOSE to enough information to do anything but know to, for example, invest in building very good structures in a known strong quake zone -- as that stringth WILL be needed - eventually.

[basil_hayden]

Thanks for the +1 oc, and for the clarifications, rd. So above-ground factors (flooding...) can have an affect on earthquakes. I wonder if the unusually large rains they have been having in the East could have played a roll, then. And perhaps also the drought and heat in the west?

Filling the Three Gorges Dam in China had an effect, I think that's the magnitude of loading you need to look for to cause seismic activity. Rain and drought - not so much.

[Outcast_Searcher]

Thanks for the +1 oc, and for the clarifications, rd. So above-ground factors (flooding...) can have an affect on earthquakes. I wonder if the unusually large rains they have been having in the East could have played a roll, then. And perhaps also the drought and heat in the west?

Filling the Three Gorges Dam in China had an effect, I think that's the magnitude of loading you need to look for to cause seismic activity. Rain and drought - not so much.

That is likely true. Scientists are certain (per a VERY cool program on the formation and evolution of the Great Lakes in the "How the Earth was Made" first season documentary series), that the ground will rise substantially over time (thousands of years), if tremendous (i.e. Great Lake proportion) amounts of waterload are removed.

So, depending on how much the magnitude of the loading of the lake(s) created by the Three Gorges Dam compares to one of the Great Lakes -- then that could have a substantial effect -- eventually.

What I have no clue of is whether that effect would be substantitve relative to earthquakes in the short (decades) time span men tend to notice.

[dohboi]

Well, after engaging in many hours, weeks, years... of research (actually, I just googled 'dams earthquakes'), I came across this, which seems to confirm bh's statements--dams can cause earthquakes in the relatively short term: http://www.internationalrivers.org/node/3845

Earthquakes Triggered by Dams

Earthquakes can be induced by dams. Globally, there are over 100 identified cases of earthquakes that scientists believe were triggered by reservoirs (see Gupta 2002). The most serious case may be the 7.9-magnitude Sichuan earthquake in May 2008, which killed an estimated 80,000 people and has been linked to the construction of the Zipingpu Dam.

[Keith_McClary]

After all, we are absolutely terrible at predicting earthquakes (aside from being able to say they will happen in certain areas periodically, and at VERY ROUGH (multi-decade) guesses, based on historical major quake frequencies.

Better than nothing but nothing CLOSE to enough information to do anything but know to, for example, invest in building very good structures in a known strong quake zone -- as that stringth WILL be needed - eventually.

Consider an hourglass with grains of sand trickling down onto a conical pile. When the pile gets a bit too steep there will be sand avalanches - sometimes tiny, sometimes large. This seems to be a chaotic process - there is no way to predict when an avalanche will occur or how large.

Like the sandpile, the whole earth is under maximum stress everywhere and could give way anywhere at any time - there is no way to predict when or how large the stress releases will be.