Volcanoes,earthquakes,magnetic fields and climatic impacts.

Rickj
Rickj
Apr 8, 2009, 7:42 AM |
0

I've been wondering for a while if the hot spots which are found around the Earth's crust are weak ponts in the earth's magnetic fields(or indeed strong popints?) Perhaps I'll call them anomolies for now.

The earth's magnetic field is changing rapidly and as it's also induced by the sun's magnetic field , which is also in a weak period, perhaps we will see an apparent increase in volcanic activity or the awakening of long dormant volcanic fields, such as the Garrotxa volcanic field in Spain or the Chaine de puys in France? We'll have to wait and see. What seems amazing this year is the volcanic and seismlic activity, in Italy, Tonga, Chile,Alaska,the Carribean, Haiwaii to name but some areas.

( http://www.volcano.si.edu/reports/usgs/)

The recent quake in Italy was notable for its strength and aftershock strength.


What causes a Volcano, or an earthquake?

Giant plates in the earth's crust.

Plate movement

Earth scientists measure the speed of plate movement by monitoring how rapidly a plate moves relative to the plate next to it. Today, plates move about 4 inches (10 centimeters) a year—about as rapidly as human hair grows. In the past, plates may have moved as fast as 6 1/4 inches (16 centimeters) per year.

The overall pattern of movement of the tectonic plates is a widening of the Atlantic Ocean and a shrinkage of the Pacific Ocean. The Atlantic is widening because sea-floor spreading at the Mid-Atlantic Ridge continues to create lithosphere. The Pacific is shrinking because much of it is ringed by convergent plate boundaries that are consuming its lithosphere.

Scientists have traced the movements of tectonic plates millions of years into the past. According to the commonly accepted description of plate movement, all the continents once formed part of an enormous single land mass called Pangaea. This mass was surrounded by a giant ocean known as Panthalassa.

About 200 million years ago, Pangaea began to break up into two large masses called Gondwanaland and Laurasia. These masses, in turn, broke up into the continents, which drifted to their present locations.

Evidence of plate movement

Earth scientists find much evidence of plate movement at the boundaries of plates. They study surface features, such as mountains and ocean trenches, and investigate the frequencies and locations of earthquakes and volcanic eruptions.

Volcanoes that rise within plates are also evidence of plate movement. Scientists believe that these volcanoes are caused by mantle plumes, columns of very hot mantle that rise from deep inside Earth to the base of the lithosphere. These plumes generate magma that rises through the lithosphere and erupts in places called hot spots.

As a plate moves over a hot spot, the spot can generate a chain of volcanoes. For example, a hot spot under the Pacific Plate generated volcanoes that became the Hawaiian islands.

Paleomagnetism (the study of magnetism in ancient rocks) also provides evidence of plate movement. The evidence is in rocks that contain magnetic particles.

When such a rock was hot and liquid, the magnetic particles moved too rapidly to be influenced by Earth's magnetic field. But as the rock cooled and solidified, the particles aligned themselves with Earth's magnetic field, like tiny compass needles. Thus, the particles continue to point in the direction of the magnetic field that was present during the time that the rock cooled.

So when the plate containing the rock either drifts to a different latitude or rotates, the particles no longer align with Earth's magnetic field. A comparison of the direction in which the particles now point in the rock with the direction of Earth's present magnetic field provides information about where the plate was when the rock solidified.

Causes of plate movement

Tectonic plates slide mostly because of temperature changes and gravity. As an edge that has formed on the ocean floor cools, it shrinks, becoming denser. After about 25 million years of cooling and shrinking, the edge becomes so dense that gravity can pull it down into the asthenosphere. There, the intense heat and increased pressure due to the great depth change the crust of the sunken plate edge into even denser rock. Because of the additional density, gravity pulls the plate edge into the asthenosphere even more strongly.

This sinking action is known as slab-pull because the sinking edge pulls the remainder of the slablike plate behind it. Many scientists believe that slab-pull is the main action driving the motion of plates with sinking edges.

Gravity also causes plates to slide downhill away from ocean ridges. This sliding force is called ridge-push.

Another cause of plate movement is the simple pushing of plates against one another. Scientists believe that large plates shove some small plates about.

The rise of mantle plumes and other movements of mantle rock may also affect the motion of tectonic plates slightly. The circulation of mantle rock as it rises to the top of the asthenosphere, cools, and then sinks is known as a convection current.

Earth scientists once thought that convection currents caused continental drift. Today, however, most Earth scientists believe that such currents are primarily a result of the sinking of plates, rather than the cause of plate motion.

A new technique for measuring the Earth's magnetic field back to the days of the dinosaurs and beyond has revealed that the field was as much as three times stronger in ancient Earth than previous techniques suggested.

The new method could help scientists better understand ancient Earth, including how its molten core behaved in its early days. The results of the first field test of the new technique appear in today's issue of Science.

Scientists use the record of the Earth's magnetic field locked in rocks to tease out secrets of the geodynamo -- the currents of molten rock that seethe beneath the Earth's crust, causing everything from earthquakes and volcanoes to the drift of the continents themselves.

The Earth's magnetic field also protects us from much of the sun's dangerous radiation, so understanding how it works can help scientists predict its fluctuations and look into what effect those fluctuations could have had on the development of life on Earth.

Researchers have known that the magnetic poles have flipped several times during our planet's lifetime -- meaning a compass 100,000 years ago could have pointed south instead of north. The record of the field is captured in tiny pieces of magnetic particles in new lava. The particles orient themselves just like a compass until the lava cools around them, locking them into place. Great bands of rock displaying north-south flips are laid across the ocean floors.

 

The traditional approach to measuring the ancient Earth's magnetic field strength (called paleointensity) was developed more than four decades ago and has changed little until Tarduno's technique.

In the old method, a piece of igneous rock about an inch across is heated and cooled in a chamber that is shielded from any magnetic sources. The magnetism is essentially "drained" from the magnetic particles in the rock, like siphoning water out of a jug. The researchers then "refill the jug," measuring how much magnetism the particles can hold.

Two significant drawbacks result from this method, however: a piece of rock hundreds of millions of years old often becomes contaminated over time, and the process often imparts a magnetism to the rock -- like water leaking into the jug before you refill it. As a consequence, very ancient samples seem to hold little magnetization, further confounding results that were already in question because of contamination.

Tarduno decided to see if he could use the University's Superconducting Quantum Interference Device (nicknamed "SQUID"), a device normally used in computing chip design, which is extremely sensitive to the tiniest magnetic fields.

Early tests showed that feldspar, the most common mineral on the Earth's surface, worked well since it created a microscopic shell around slivers of magnetite, protecting them from contamination.

Tarduno's team took samples from a 1955 lava flow in Hawaii and tried to determine if the paleointensity reading would match the actual Earth's magnetic field strength in 1955. It did. Tarduno was essentially doing the same heating/cooling test that had been done for 40 years on large samples, yet doing it on samples the size of a grain of sand, without the possibility of contamination and with much more accurate results.

"We can now measure paleointensity in places we could never measure anything before," says Tarduno. "And the results are more reliable than ever before."

With the method tested, it was time for Tarduno to see what it revealed about the magnetic field back in the days of the dinos. His team took dozens of samples from lava flows in India that were nearly 100 million years old -- an unusual time in Earth's history when the field was not reversing -- and found that the intensity of the field was three times stronger than the old method suggested.

Besides possibly giving T-Rex a better northern lights show, the field strength gives researchers a glimpse into what the Earth's hot, molten core was doing back then.

"Our findings suggest that there is a relationship between magnetic reversals and paleointensity," says Tarduno. "Such a relationship fits very well with supercomputer models. It's an exciting time. We're really starting to understand how the heart of our planet works."

Tarduno will use the new method to plot the paleointensity of different eras in ancient Earth's past. Some of his more challenging work is in the paleointensity of rocks 2.5 billion years old -- more than halfway back to Earth's very beginning. The task is especially challenging because scientists believe that the core of the Earth that controls the magnetic field was still forming.


Magnetic Reversals

After molten lava emerges from a volcano, it solidifies to a rock. In most cases it is a black rock known as basalt, which is faintly magnetic, like iron emerging from a melt--for which Gilbert already noticed a similar process. Its magnetization is in the direction of the local magnetic force at the time when it cools down.

Instruments can measure the magnetization of basalt. Therefore, if a volcano has produced many lava flows over a past period, scientists can analyze the magnetizations of the various flows and from them get an idea on how the direction of the local Earth's field varied in the past. Surprisingly, this procedure suggested that times existed when the magnetization had the opposite direction from today's. All sorts of explanation were proposed, but in the end the only one which passed all tests was that in the distant past, indeed, the magnetic polarity of the Earth was sometimes reversed.

No one knows when the next field reversal will occur: in the past, they have occurred on the average about once in 500,000 years. The change, whenever it occurs, will be gradual and the field will not drop to zero in between--doing so would mean that the magnetic energy of the Earth was somehow converted or dissipated, and all processes we know for this tend to run on scales of thousands of year, if not more. Right now the main (dipole) field is getting weaker at a rate of about 7% per century, and if you draw a straight line through the points you find it reversing between 1000 and 2000 years from now. It might happen, although the trend may well change. The energy of the field, however, has hardly changed. What seems to have happened is that the more complicated parts of the field (equivalent to several magnets in different directions) have got stronger while the main two-pole ("dipole") field lost strength. The complex field is somewhat weaker (it drops off faster with distance from the source, which is the core of the Earth), but we should not expect the field to be ever greatly weakened.

The polar field of the Sun seems to reverse every 11 years or so, taking about a year or more. But the Sun's magnetism is different, it has foci right on the surface, in sunspots.

Is the Earth's field getting weaker? Yes and no. That field is often viewed as being a two-pole ("dipole") structure similar to that of a small bar-magnet at the center of the Earth, inclined by about 11 degrees to the rotation axis of the Earth, so that the magnetic poles are not the same as the geographic ones. But the actual situation is more complicated, and magnetic charts note the fact by mapping deviations between magnetic north and the direction to the magnetic pole, which fit no simple pattern.

Why? Because the magnetic field is actually more complicated, and it contains additional fields, of more complex nature. All this originates in the Earth's core, about half the radius of the Earth. If we could go to the surface of the core, all the complicated parts would be much bigger. But they weaken more rapidly with distance, so at the surface of the Earth they are already quite weak, while the "dipole" part stands out more (in addition of actually BEING the biggest chunk of the field).

Are you still with me?

The magnetic field of the Earth changes all the time, and yes, magnetic charts have to be redrawn from time to time (this was first found in 1641, by an Englishman named Gellibrand). And yes, in the century and a half since the first careful mapping of the Earth's field, the dipole has become weaker by about 8% (the rate may have speeded up in 1970). If you draw a straight line through the points, you will find that perhaps 1200 years from now, the line goes through zero.

Extending straight lines too far beyond the present, however, is risky business, as noted by no less a scientific authority than Mark Twain. In "Life on the Mississippi" Twain noted that the Mississippi river was getting progressively shorter (mainly by floods--and by people--creating shortcuts through bends in the river) and he wrote:


In the space of one hundred and seventy six years the lower Mississippi has shortened itself two hundred and forty-two miles. That is an average over a mile and a third per year. Therefore, any calm person, who is not blind or idiotic, can see that in the lower Oolitic Silurian Period, just a million years ago next November, the lower Mississippi was upward of one million three hundred thousand miles long, and stuck out over the Gulf of Mexico like a fishing rod. And by the same token any person can see that seven hundred and forty years from now the lower Mississippi will be only a mile and three quarters long, and Cairo and New Orleans will have joined their streets together, and will be plodding comfortably along under a single mayor.


It is not likely that the magnetic field will go through zero 1200 years from now. When one uses observations on the surface to reconstruct fields at the core, one finds that while the dipole field is getting weaker, the complicated parts are getting stronger, and the total magnetic energy does not change, within our observational accuracy.

I don't know about migrating animals (they may have magnetic organs, sort of built-in compasses), but there seem to exist no magnetic effects on DNA, resistance to antibiotics and so on; those changes seem more related to chemistry.

Finally, be cautious with compass readings in your house. Houses do contain electric currents and machinery, and these may affect the readings of a magnetic compass. On NASA's satellites the magnetic sensor usually sits at the end of a long boom, to keep it away from interfering electric currents in the satellite's circuits.

 

Compare two maps, and note the ring of fire and the magnetic map.

magnetic field of the earth

Volcano map

http://vulcan.wr.usgs.gov/Glossary/PlateTectonics/Maps/map_plate_tectonics_world.html

 

Why I'm worried? Because the Earth's magnetic field has a massive breach(see here http://wattsupwiththat.com/2008/12/16/earths-magnetic-field-has-massive-breach-

scientists-baffled/)

If the Earths magnetic field weakens, will volcanism and plate techtonics increase?

The earth's magnetic field also affect us

http://www.newscientist.com/article/dn16871-sweet-dreams-are-made-of-geomagnetic-activity.html

http://www.swpc.noaa.gov/info/Kindex.html

What about earthquakes?

http://neic.usgs.gov/neis/eqlists/eqstats.html

and

http://neic.usgs.gov/neis/eqlists/graphs.html

shows the stats, and states that earthquake activity isn't increasing, but the graphs say otherwise.

 

What about volcanoes?

The historical record of large volcanic eruptions from 1500 to 1980, as contained in two recent eruption catalogs, is subjected to detailed time series analysis. Two weak, but probably statistically significant, periodicities of ∼11 and ∼80 years are detected. Both cycles appear to correlate with well-known cycles of solar activity; the phasing is such that the frequency of volcanic eruptions increases (decreases) slightly around the times of solar minimum (maximum). The weak quasi-biennial solar cycle is not obviously seen in the eruption data, nor are the two slow lunar tidal cycles of 8.85 and 18.6 years. Time series analysis of the volcanogenic acidities in a deep ice core from Greenland, covering the years 553–1972, reveals several very long periods that range from ∼80 to ∼350 years and are similar to the very slow solar cycles previously detected in auroral and carbon 14 records. Mechanisms to explain the Sun-volcano link probably involve induced changes in the basic state of the atmosphere. Solar flares are believed to cause changes in atmospheric circulation patterns that abruptly alter the Earth's spin. The resulting jolt probably triggers small earthquakes which may temporarily relieve some of the stress in volcanic magma chambers, thereby weakening, postponing, or even aborting imminent large eruptions. In addition, decreased atmospheric precipitation around the years of solar maximum may cause a relative deficit of phreatomagmatic eruptions at those times.

Also, with the sun changing it's magnetic field,we are now officially in a deep solar minimum according to Nasa

http://science.nasa.gov/headlines/y2009/01apr_deepsolarminimum.htm?list737744

Which probably means we are not.

Looking at this graph we can see 1911, 1912 and 1913 being three low years in a row, and 2007,2008 and 2009 could be compared, with 2007 being of a similar nature to 1911, 2008 being of a similar magnitude to 1912, and 2009 perhaps being like 1913

 

It is now possible to bring together recent, previously unknown, and amazing correlations
that have been shown to exist between different parts of the solar wind -
magnetosphere - ionosphere - solid Earth system, in particular with respect to earthquake
activity. There is strong evidence of electromagnetic processes responsible for
earthquake triggering, that we study extensively.We will focus here on one correlation
between power in solar wind compressional fluctuations and power in magnetospheric
pulsations and ground H component fluctuations. The variation of the horizontal component
H of the geomagnetic field is the crucial parameter in the Magneto-Seismic
Effect MSE to be discussed in a companion paper. The connection of earthquake activity
to possible solar or solar wind drivers is not well understood; many authors have
attempted correlations in the past with mixed results. We will use data from the S3C
Great Observatory and from ground-based magnetometer arrays to show long term
trends near solar minimum for ultra low frequency (ULF) fluctuations, specifically
the Pc5 (˜1 - 8 mHz) band. For the satellites we will also demonstrate the entry of
compressional Pc5 energy and waves at the dayside magnetopause, and the transport
through the magnetosphere for selected events in 2002. The ionosphere modulates
waves transmitted to the ground so we only compare the wave power and not the
waves themselves for the ground-based magnetometers.

http://www.cfa.harvard.edu/~wsoon/1816-Mercury03-d/Summer_of_1816.pdf

 

One thing is for sure and that is that in previous great minima, we have seen enormous volcanic eruptions, such as that of Tambora during solar minimums

 

Table I. Comparison of selected volcanic eruptions
Eruptions Year Column
height (km)
VEI N. hemisphere
summer anomaly (°C)
Fatalities
Mount Vesuvius 79 30 5 ? >2000
Taupo 186 51 7 ?
Baekdu 969 25 6–7 ? ?
Kuwae 1452 ? 6 −0.5 ?
Huaynaputina 1600 46 6 −0.8 ≈1400
Tambora 1815 43 7 −0.5 > 71,000
Krakatau 1883 25 6 −0.3 36,600
Santamaría 1902 34 6 no anomaly 7,000–13,000
Katmai 1912 32 6 −0.4 2
Mt. St. Helens 1980 19 5 no anomaly 57
El Chichón 1982 32 4–5 ? > 2,000
Nevado del Ruiz 1985 27 3 no anomaly 23,000
Pinatubo 1991 34 6 −0.5 1202

Source: Oppenheimer (2003),[4] and Smithsonian Global Volcanism Program for VEI.[22]

 

 

How many of these eruptions happened at solar minimum?I can go back as far as 1710

Tambora, Krakatau, Nevado del ruiz, Katmai ,Santamria, all seem to be at solar minimums.

 

 

 

 

 

http://en.wikipedia.org/wiki/List_of_solar_cycles

If we look at the list of deadliest volcanic eruptions

Top 10 deadliest volcanic eruptions

Death Toll  ↓ Event  ↓ Location  ↓ Date  ↓
$ 2 million in Russia alone, from resultant famine Huaynaputina (see also Russian famine of 1601–1603) Peru 01815-01-011600
$ 92,000 Mount Tambora (see also Year Without a Summer) Indonesia 01815-01-011815
$36,000 Krakatoa Indonesia 01883-08-26August 26–27, 1883
$29,000 Mount Pelée Martinique 01902-05-07May 7 or May 8, 1902
$23,000 Nevado del Ruiz Colombia 01985-11-13November 13, 1985
$25,000 Mount Vesuvius Italy 01631-01-011631
$15,000 Mount Unzen Japan 01792-01-011792
$10,000 Mount Kelut Indonesia 01586-01-011586
$9,350 Laki. Killed about 25% of the population (33% were killed about 70 years before by smallpox) Iceland 01783-06-08 June 8, 1783
$6,000 Santa Maria Guatemala 01902-01-011902
$5,115 Mount Kelut Indonesia 01919-05-19 May 19, 1919

Which ones here were at solar minimum?

or even earthquakes

Earthquakes

Death Toll  ↓ Event  ↓ Location  ↓ Date  ↓
$830,000 1556 Shaanxi earthquake China 1556
$286,000 2004 Indian Ocean earthquake Indonesia, Sri Lanka, India, Thailand 2004
$255,000 1976 Tangshan earthquake China 1976
$240,000 1920 Haiyuan earthquake China 1920
$ 230,000 1138 Aleppo earthquake Syria 1138
$200,000 Damghan earthquake Iran 856
$150,000 Ardabil earthquake Iran 893
$137,000 1730 Hokkaidō earthquake Japan 1730
$110,000 1948 Ashgabat earthquake Turkmenistan 1948
$105,000 Great Kanto earthquake Japan 1923
$100,000 Messina earthquake Italy 1908
$100,000 1755 Lisbon earthquake Portugal 1755
$100,000 Chihli earthquake China 1290
$86,000 2005 Kashmir earthquake Pakistan 2005
$85,000 Great Ansei Nankai Quakes, Japan (安政南海地震) Japan 1854
$80,000 Shamakhi Azerbaijan 1667
$77,000 Tabriz Earthquake Iran 1727
$70,000 Changma, Gansu earthquake China 1932
$ 69,197 2008 Sichuan earthquake China 2008
$66,000 Ancash earthquake Peru 1970
$60,000 Sicily earthquake[2] Italy 1693
$60,000 1935 Balochistan earthquake British India 1935
$50,000 Calabria earthquake Italy 1783
$40,000 Gulang, Gansu earthquake China 1927
$40,000 Meiō Nankai, Japan (明応地震) earthquake Japan 1498
$40,000 Quito earthquake Ecuador 1797
$37,000 Genroku earthquake (元禄大地震) Japan 1703
$35,000 1990 Manjil Rudbar earthquake Iran 1990
$32,962 Erzincan earthquake Turkey 1939
$30,000 Great Hōei Earthquake (宝永大地震) Japan 1707
$ 30,000 2003 Bam earthquake Iran 2003
$25,000 Spitak Earthquake Armenia 1988
$25,000 1978 Tabas earthquake Iran 1978
$23,700 Kamakura earthquake Japan 1293
$23,000 Guatemala earthquake Guatemala 1976
$20,000 Gujarat earthquake India 2001
$20,000 1812 Caracas earthquake Venezuela 1812
$20,000 Chillán earthquake Chile 1939
$18,000 Khait earthquake Tajikistan 1949
$17,118 Izmit earthquake Turkey 1999
$15,000 1960 Agadir earthquake Morocco 1960
$10,700 1934 Bihar earthquake India 1934
$9,748 1993 Latur earthquake India 1993
$9,500 1985 Mexico City earthquake Mexico 1985
$9,000 1933 Diexi earthquake China 1933
$8,064 1966 Xingtai Earthquake China 1966
$6,000 1960 Valdivia earthquake Chile 1960
$5,300 1974 Hunza earthquake Pakistan 1974
$4,000 1945 Balochistan earthquake British India 1945
$3,894 1948 Fukui earthquake Japan 1948
$3,000 1933 Sanriku earthquake Japan 1933
$3,000 1906 San Francisco earthquake United States

1906