8.8 quake rocks Chile - Earthquake discussion thread

[Azathoth]

See, the CONDITIONING is showing. plate tectonics is a LIE. The earth is HOLLOW and HAARP rings it like a bell

[Thumpalumpacus]

Largest quake in history was in Chile, in 1960, at 9.5.

Living in California, I've rolled through Coalinga '83, Whittier '87, Northridge '94 (from distances varying from 20 - 70 miles), and Paso Robles 03; but all of those pale compared to an 8.8.

Being a native Texan, and having been through two tornadoes -- one within a 1/4 mile from my home -- I can easliy say I'll take the tornados any day of the week. They're predictable to an extent, and you can go to your storm cellar and ride it out. Don't try that in an earthquake.

[Salviati]

Intuitvely, it appears to me that these days we're getting an awful lot of naturally occurring catastrophes. More than our fair share. I wonder if global warming might be in on this.

Of course, intuition by itself, on this subject, is worth little to nothing. I'd be interested to see the relevant statistics.

[klazmon]

The largest quake ever recorded was also in Chile. Mag 9.5 in 1960.

I happened to have a look on google earth yesterday as I wasn't exactly sure where Concepcion was in relation to Santiago and a see they had the main quake and aftershocks showing as little orange buttons with a zigzag on. The number of aftershocks showing was jaw dropping, several greater than mag 6. Many of them have disappeared off the map including the big one as I guess they only display for a certain number of hours after the quake. There are still about thirty aftershocks showing though.

[klazmon]

Intuitvely, it appears to me that these days we're getting an awful lot of naturally occurring catastrophes. More than our fair share. I wonder if global warming might be in on this.

Of course, intuition by itself, on this subject, is worth little to nothing. I'd be interested to see the relevant statistics.

The general seismic activity has been higher than average over the last twenty years but I doubt it has anything to do with global warming. You could get a small rebound effect in areas where a lot of land based ice melted but these sort of major quakes that occur on the ring of fire are due to the vast tectonic pressure that the Earth's mantle applies to the crust. This quake released energy equivalent to around sixteen billion tons of TNT exploding.

[Xamonas Chegwé]

Chile is right next to one of the most active fault-lines on Earth. The Nazca plate is subducting under the South American plate all the time. This is what formed (and is still forming) the Andes.

They have quakes several times a year and major quakes every few years. Santiago makes San Francisco look stable.

So yes, it's global worming that is causing it.

[macdoc]

Actually despite the smirk there may be some truth to that.

Fire and Ice: Melting Glaciers Trigger Earthquakes, Tsunamis and ...
Melting glaciers caused by global warming will lead to an increasing number of earthquakes, tsunamis and volcanic eruptions, according to geologists who ...

http://environment.about.com/od/globalw ... quakes.htm

You can't shift the cryosphere the way we have ...400-600 cuKM per annum without some geologic consequences

••

The other aspect as well is changes in ground water caused by melting glaciers may have a role in releasing quakes. The Andes glaciers have seen dramatic changes and rather than rebound it may be hydrology issues there.

Groundwater Effects from Earthquakes
27 Oct 2009 ... However, seismic waves seem to be able to cause groundwater level changes in other ways, and these changes can show up in either confined or ...

http://earthquake.usgs.gov/learn/topics/groundwater.php

There is clear interaction with groundwater structures and we are altering ground water hydrology massively in some ares - aquifers are dropping and in India it's so bad it is detectable in sea level rise

Ground-water studies for earthquake prediction in China
by W Chengmin - 1984 - Cited by 1 - Related articles
Anomalous water changes before earthquakes. During the past 15 years, anomalous ground-water changes have been observed before more than 60 earthquakes, ...

http://www.springerlink.com/index/W3R724MT80285W01.pdf

[klazmon]

At the end of the last Ice age, the melt was massive. If there is anything more than local rebound you would expect to see a great deal of evidence for abnormal earthquake/volcanic activity around 11 or 12 thousand years ago.

[macdoc]

Well certain areas are still rebounding...northern north america/hudson bay area.

I would think determining a link with seismic and ice age end might be tricky given all the other land form changes that would be going on...

Still the processes never end and the planet has a slow breath cycle over time as well as hotter and cooler as the Milankovch cycles shift the conditions...

West coast NA certainly faces multiple risks from direct volcanism ( ranier ) and earthquake direct and via tsunami.
Shaky coast indeed.

[ginckgo]

At the end of the last Ice age, the melt was massive. If there is anything more than local rebound you would expect to see a great deal of evidence for abnormal earthquake/volcanic activity around 11 or 12 thousand years ago.

Here ya go:

The time series of volcanically produced sulfate from the GISP2 ice core is used to develop a continuous record of explosive volcanism over the past 110,000 yr. We identified not, vert, similar850 volcanic signals (700 of these from 110,000 to 9000 yr ago) with sulfate concentrations greater than that associated with historical eruptions from either equatorial or mid-latitude regions that are known to have perturbed global or Northern Hemisphere climate, respectively. This number is a minimum because decreasing sampling resolution with depth, source volcano location, variable circulation patterns at the time of the eruption, and post-depositional modification of the signal can result in an incomplete record. The largest and most abundant volcanic signals over the past 110,000 yr, even after accounting for lower sampling resolution in the earlier part of the record, occur between 17,000 and 6000 yr ago, during and following the last deglaciation. A second period of enhanced volcanism occurs 35,000–22,000 yr ago, leading up to and during the last glacial maximum. These findings further support a possible climate-forcing component in volcanism. Increased volcanism often occurs during stadial/interstadial transitions within the last glaciation, but this is not consistent over the entire cycle. Ages for some of the largest known eruptions 100,000–9000 yr ago closely correspond to individual sulfate peaks or groups of peaks in our record.

and

Intra-plate volcanism in western Europe shows statistically significant episodicity during the Quaternary period. By comparing the known ages for eruptions in France and Germany, which are compiled here, with a composite oxygen isotope record, we have investigated the link between this episodic volcanism and the climate record over the last two million years. We show that increased volcanism between 415-400 ka and 17-5 ka correlates with warming phases at the end of the last Weichselian (Devensian) and earlier Elsterian (Anglian) glacial stages. The three significant caldera explosions in the eastern Eifel, Germany, are all associated with warming phases at the onset of interglacials. The growth and decay of nearby ice sheets suggest that surface changes in continental mass distribution during glacial Milankovich cycles could provide a mechanism for this correlation by means of the distal effects of flexural loading on the lithosphere.

Though I doubt how much influence current climate change would have had on this Chilean earthquake. Normal Plate tectonics would be cause enough.

Though I thought it was interesting looking at the wikipedia list of most severe earthquakes, 10 out of the 18 listed occur after 1950. Even allowing for the fact that estimating earthquake magnitudes before then would be difficult (yet there are 5 pre-1900 earthquakes on the list), that's quite a high rate. And 4 of them have been in the last 10 years.

On the other hand they reckon that since 1900 the rate of earthquake occurrences has been relatively constant, even decreasing recently.

[klazmon]

That's the sort of thing I was looking for. Thank you Ginckgo.

[hotshoe]

A NASA lab has just calulated that the Chile earthquake shortened the Earth's day, speeding our rotation by redistributing mass closer to the center.

Richard Gross, a scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif., and colleagues calculated that Saturday's quake shortened the day by 1.26 microseconds. A microsecond is one-millionth of a second.

The length of a day is the time it takes for the planet to complete one rotation — 86,400 seconds or 24 hours.

An earthquake can make Earth rotate faster by nudging some of its mass closer to the planet's axis, just as ice skaters can speed up their spins by pulling in their arms. Conversely, a quake can slow the rotation and lengthen the day if it redistributes mass away from that axis, Gross said Tuesday.

Read more

Note his admission that the change is not only imperceptible to unaided humans, it is not even measurable with instruments and has to be calculated instead.

[Fact-Man]

On the other hand they reckon that since 1900 the rate of earthquake occurrences has been relatively constant, even decreasing recently.

And certainly as Earth cools over the longer haul, earthquake activity will only decline and plate tectonics will slow to a crawl and then cease altogether. That will probably entail tens of thousands of millennia, but it is the inevitable outcome.

What of climate could overwhelm or affect the forcing of the energy rising from Earth's molten core?

At bottom it is that energy that's the ultimate cause of all earthquakes. Earth is wrinkling like the skin of a drying apple, and every time it wrinkles a tad more, we get an earthquake.

[Xamonas Chegwé]

On the other hand they reckon that since 1900 the rate of earthquake occurrences has been relatively constant, even decreasing recently.

And certainly as Earth cools over the longer haul, earthquake activity will only decline and plate tectonics will slow to a crawl and then cease altogether. That will probably entail tens of thousands of millennia, but it is the inevitable outcome.

What of climate could overwhelm or affect the forcing of the energy rising from Earth's molten core?

At bottom it is that energy that's the ultimate cause of all earthquakes. Earth is wrinkling like the skin of a drying apple, and every time it wrinkles a tad more, we get an earthquake.

I am not sure about that. Don't the gravitational forces of the sun and moon impart stresses that help keep the Earth from cooling? I know that such things happen to the satellites of the larger planets. (This might well have come straight out of my arse, so feel free to correct me.)

[klazmon]

On the other hand they reckon that since 1900 the rate of earthquake occurrences has been relatively constant, even decreasing recently.

And certainly as Earth cools over the longer haul, earthquake activity will only decline and plate tectonics will slow to a crawl and then cease altogether. That will probably entail tens of thousands of millennia, but it is the inevitable outcome.

What of climate could overwhelm or affect the forcing of the energy rising from Earth's molten core?

At bottom it is that energy that's the ultimate cause of all earthquakes. Earth is wrinkling like the skin of a drying apple, and every time it wrinkles a tad more, we get an earthquake.

I am not sure about that. Don't the gravitational forces of the sun and moon impart stresses that help keep the Earth from cooling? I know that such things happen to the satellites of the larger planets. (This might well have come straight out of my arse, so feel free to correct me.)

That effect is relatively small for the Earth IIRC. The sources of heat in the Earth are as follows:

1. Residual heat from accretion (gravity)
2. Residual heat released from density separation. ie the formation of the crust, mantle and core. (gravity)
3. The phase change of the inner core from liquid to solid (latent heat). Supposedly this is still occurring as the Earth slowly cools, the solid inner core is slowly growing.
4. Tidal friction (gravity)
5. The biggie (~80-90%). Radioactive decay of elements that were formed in an ancient supernova.