Monday, November 30, 2015

[Volcano_Vista_HS] VVHS Announcements--Monday, November 30, 2015



Attention Juniors!  There will be a class meeting on Wednesday in A101.  All Juniors are welcome!

 

Junior Senate - We are in charge of Snack Bar this week.  Please be sure to show up on the days you are signed up for!

 

DECA will be collecting items such as: Toys, books, movies, Xbox 360 games and board games. Turn items into the academy offices or to H-111. All items will be donated to the Presbyterian Children's Oncology Unit.

 

DECA MOVIE NIGHT: There will be a movie night in the lecture hall showing Elf, (Santa, I know him!) on Thursday December 3rd at 6pm. There is no entry fee but we encourage you to bring a donation.

 

SIGN LANGUAGE CLUB will be meeting in Mrs. Martin's room, E205, at lunch today.

 

PB & J: Student senate is sponsoring the PB & J Wish project. If your club, team or class would like to adopt a child for the holidays and provide them with their wish list stop by the Activities Office and pick up a name. All gifts need to be returned by Wednesday, December 9.

 

Seniors: There will be a senior class meeting in Mrs. Valdez's room on Wednesday during lunch.

 

ATHLETICS:

  • GIRLS BASKETBALL plays the Eldorado Eagles on Tuesday night at 7 in the Ring of Fire. 

  • WRESTLING has their first match on Wednesday at 5:45 against the Del Norte Knights and at 7 against the Highland Hornets in the Ring of Fire.

 

Have a great day

And remember                                                      

As always…

It's great to be a Hawk!



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Posted by: ssteckbeck@yahoo.com


For more information, go to our web site: http://www.volcanovistahawks.com




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Re: [Geology2] Earth not due for a geomagnetic flip in the near future



Thank you Rick.. this was very helpful. Allison



On Sunday, November 29, 2015 7:24 PM, "'Rick Bates (WA6NHC)' wa6nhc@gmail.com [geology2]" <geology2@yahoogroups.com> wrote:


 
http://www.pbs.org/wgbh/nova/earth/when-our-magnetic-field-flips.html

Rick WA6NHC

Tiny iPhone keypad, spell check happens

On Nov 29, 2015, at 4:37 PM, Allison Maricelli-Loukanis allison.ann@att.net [geology2] <geology2@yahoogroups.com> wrote:

 
I will watch for it. Allison



On Saturday, November 28, 2015 12:21 AM, "Kim Noyes kimnoyes@gmail.com [geology2]" <geology2@yahoogroups.com> wrote:


 
A lot more of the Aurora Borealis and a bit more cancer. There is a great NOVA episode about this.

On Thu, Nov 26, 2015 at 10:31 AM, 'allison.ann@att.net' allison.ann@att.net [geology2] <geology2@yahoogroups.com> wrote:
 
Interesting but I'd like to know in practical terms what we would see in a magnetic pole flip. Allison

Sent from my Sprint phone.

----- Reply message -----
From: "Lin Kerns linkerns@gmail.com [geology2]" <geology2@yahoogroups.com>
To: <undisclosed-recipients:>
Subject: [Geology2] Earth not due for a geomagnetic flip in the near future
Date: Wed, Nov 25, 2015 8:02 AM

 
Public Release: 23-Nov-2015

Earth not due for a geomagnetic flip in the near future

Researchers find geomagnetic field intensity is double the long-term historical average
Massachusetts Institute of Technology
The intensity of Earth's geomagnetic field has been dropping for the past 200 years, at a rate that some scientists suspect may cause the field to bottom out in 2,000 years, temporarily leaving the planet unprotected against damaging charged particles from the sun. This drop in intensity is associated with periodic geomagnetic field reversals, in which the Earth's North and South magnetic poles flip polarity, and it could last for several thousand years before returning to a stable, shielding intensity.
With a weakened geomagnetic field, increased solar radiation might damage electronics -- from individual pacemakers to entire power grids -- and could induce genetic mutations. A reversal may also affect the navigation of animals that use Earth's magnetic field as an internal compass.
But according to a new MIT study in the Proceedings of the National Academy of Sciences, the geomagnetic field is not in danger of flipping anytime soon: The researchers calculated Earth's average, stable field intensity over the last 5 million years, and found that today's intensity is about twice that of the historical average.
This indicates that the current field intensity has a long way to fall before reaching an unstable level that would lead to a reversal.
"It makes a huge difference, knowing if today's field is a long-term average or is way above the long-term average," says lead author Huapei Wang, a postdoc in MIT's Department of Earth, Atmospheric and Planetary Sciences. "Now we know we are way above the unstable zone. Even if the [field intensity] is dropping, we still have a long buffer that we can comfortably rely on."
Flip-flopping through history
Earth has undergone multiple geomagnetic reversals over its lifetime, flip-flopping its polarity at random intervals.
"Sometimes you won't have a flip for about 40 million years; other times there will be 10 flips in 1 million years," Wang says. "On average, the duration between two flips is a few hundred thousand years. The last flip was around 780,000 years ago, so we are actually overdue for a flip."
The most obvious sign of an impending reversal is a geomagnetic field intensity that's significantly below its historical, long-term average -- a sign that the planet is tipping toward an unstable state. While satellites and ground-based observatories have made accurate measurements over the last 200 years of the current field intensity, there are less reliable estimates over the last few million years.
Wang and his colleagues, from Rutgers University and France, sought to measure Earth's paleomagnetic field using ancient rocks erupted from volcanoes on the Galapagos Islands -- an ideal site, since the island chain is on the equator. As Earth's magnetic field, in its stable configuration, is a dipole, the intensity of the field should be the same at both poles, and half that intensity at the equator.
Wang reasoned that knowing the paleomagnetic field intensity at the equator and the poles would therefore give an accurate estimate of the planet's average historical intensity.
Rocks from a dipole
Wang obtained samples of ancient volcanic lavas from the Galapagos, while his colleagues from the Scripps Institution of Oceanography at the University of California at San Diego excavated similarly aged rocks from Antarctica. Such volcanic rocks retain information on the geomagnetic field intensity at the time they cooled.
The two teams brought the samples back to their respective labs, and measured the rocks' natural remanent magnetization, or orientation of ferromagnetic particles. They then heated the rocks, and cooled them in the presence of a known magnetic field, measuring the rocks' magnetization after cooling.
A rock's remanent magnetization is proportional to the magnetic field in which it cooled. Therefore, using the data from their experiments, the researchers were able to calculate the peak distribution of the ancient geomagnetic field intensity, both at the equator -- about 15 microtesla -- and the poles -- about 30 microtesla. Today's field intensities at the same locations are around 30 microtesla and 60 microtesla, respectively -- double the historical, long-term values.
"That means today's value is anomalously high, and even if it's dropping, it's dropping to a long-term average, not from an average to zero," Wang says.
Far from zero
So why have scientists assumed that Earth's geomagnetic field is dropping to a precipitous low? It turns out this assumption is based on flawed historical data, Wang says.
Scientists have estimated paleomagnetic intensities at various latitudes around the Earth, but Wang's is the first data from equatorial regions. However, Wang found that scientists were misinterpreting how rocks recorded their magnetic fields, leading to inaccurate estimates of paleomagnetic intensity. Specifically, scientists were assuming that as individual ferromagnetic grains of rocks cooled, their unpaired electron spins assumed a uniform orientation, reflecting the magnetic field intensity.
However, this effect only holds true up to a certain size. In larger grains, unpaired electron spins assume various orientations in different domains of the grain, thereby complicating the field intensity picture.
Wang developed a method to correct for such multidomain effects, and applied the method to his Galapagos lavas. The results, he says, are more reliable than previous estimates of the paleomagnetic field.
As for when Earth may experience its next flip, Wang says the answer is still up in the air.
"What I can say is, if you keep a constant present-day decrease rate, it will take another 1,000 years for the field to drop to its long-term average," Wang says. "From there, the field intensity may go up again. There's really no way to predict what will happen after that, given the random nature of the magnetohydrodynamic process of the geodynamo."
http://www.eurekalert.org/pub_releases/2015-11/miot-end112315.php
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Posted by: Allison Maricelli-Loukanis <allison.ann@att.net>



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[Geology2] Rare fossil of a horned dinosaur found from 'lost continent'



Rare fossil of a horned dinosaur found from 'lost continent'


The leptoceratopsids have a beak-shaped jaw suggesting
they had a different diet to their western relatives.
A rare fossil from eastern North America of a dog-sized horned dinosaur has been identified by Dr Nick Longrich. The fossil provides evidence of an east-west divide in North American dinosaur evolution.

During the Late Cretaceous period, 66-100 million years ago, the land mass that is now North America was split in two continents by a shallow sea, the Western Interior Seaway, which ran from the Gulf of Mexico to the Arctic Ocean. Dinosaurs living in the western continent, called Laramidia, were similar to those found in Asia.

However, few fossils of animals from the eastern 'lost continent' of Appalachia have been found because these areas being densely vegetated, making it difficult to discover and excavate fossils.

Dr Longrich, from the Milner Centre for Evolution based in our Department of Biology & Biochemistry, studied one of these rare fossils, a fragment of a jaw bone kept in the Peabody Museum at Yale University. It turned out to be a member of the horned dinosaurs - the Ceratopsia.

His study, published in the journal Cretaceous Research, highlights it as the first fossil from a ceratopsian dinosaur identified from this period of eastern North America.

Plant-eating horned dinosaur

Ceratopsia is a group of plant-eating horned dinosaurs that lived in the Cretaceous period. The fossil in question comes from a smaller cousin of the better known Triceratops, the leptoceratopsids. It was about the size of a large dog.

The specimen studied by Longrich was too incomplete to identify the exact species accurately, but showed a strange twist to the jaw, causing the teeth to curve downward and outwards in a beak shape.

The jaw was also more slender than that of Ceratopsia found in western North America, suggesting that these dinosaurs had a different diet to their western relatives, and had evolved along a distinct evolutionary path.

Dr Nick Longrich explained: "Just as many animals and plants found in Australia today are quite different to those found in other parts of the world, it seems that animals in the eastern part of North America in the Late Cretaceous period evolved in a completely different way to those found in the western part of what is now North America due to a long period of isolation.

"This adds to the theory that these two land masses were separated by a stretch of water, stopping animals from moving between them, causing the animals in Appalachia to evolve in a completely different direction, resulting in some pretty weird looking dinosaurs.

"Studying fossils from this period, when the sea levels were very high and the landmasses across the Earth were very fragmented, is like looking at several independent experiments in dinosaur evolution.

"At the time, many land masses - eastern North America, Europe, Africa, South America, India, and Australia - were isolated by water.

"Each one of these island continents would have evolved its own unique dinosaurs - so there are probably many more species out there to find."

Reference:
Nicholas R. Longrich. A ceratopsian dinosaur from the Late Cretaceous of eastern North America, and implications for dinosaur biogeography, Cretaceous Research (2016). DOI: 10.1016/j.cretres.2015.08.004

Note: The above post is reprinted from materials provided by University of Bath.
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Posted by: Lin Kerns <linkerns@gmail.com>



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[Geology2] Soil pulled from deep under Oregon's unglaciated Coast Range unveils frosty past climate



Soil pulled from deep under Oregon's unglaciated Coast Range unveils frosty past climate

Landscapes across much of North America were colder, eroded rapidly from cracking frost during the last ice age, according to research

Date:
November 27, 2015
Source:
University of Oregon
Summary:
Lush greenery rich in Douglas fir and hemlock trees covers the Triangle Lake valley of the Oregon Coast Range. Today, however, geologists are more focused on sediment samples dating back 50,000 years and which show the region, not covered by glaciers in the last ice age, was frost-covered and endured erosion rates must higher than those seen today.

A work crew operates a drilling rig near Little Lake in the Oregon Coast Range, where researchers pulled up a buried archive of sediment that helped them detail climate changes dating to a massive landslide 50,000 years ago. The location is just west of the community of Triangle Lake that sits on the edge of a larger lake with that name. The valley is about 40 miles northwest of Eugene, Oregon.
Credit: Photo by Daniel Gavin

Lush greenery rich in Douglas fir and hemlock trees covers the Triangle Lake valley of the Oregon Coast Range. Today, however, geologists across the country are more focused on sediment samples dating back 50,000 years that were dug up by University of Oregon scientists.

The sediment indicates that the mountainous region, which was not covered in glaciers during the last ice age, was a frost-covered grassy landscape that endured erosion rates at least 2.5 higher than today's, an eight-member team reports in a paper in the journal Science Advances.

The research raises the possibility that non-glaciated terrain across North America was similar to that found 40 miles northwest of Eugene. The findings also suggest that mean annual temperatures were about 11 degrees Celsius cooler than modern temperatures, and that frost cracking -- not rainfall -- drove erosion as the region began emerging out of the Last Glacial Maximum.

Core samples containing telling signatures of frost were drilled up from 200 feet below today's surface near Little Lake. The valley, also home to the much larger Triangle Lake, is the result of a massive landslide 50,000 years ago. Eroding sediment then continued to fill a large lake and transform the valley floor.

UO doctoral student Jill A. Marshall led the National Science Foundation-funded research under the direction of Joshua J. Roering, a professor in the UO Department of Geological Sciences.

"I remember running into Josh's office and interrupting him to exclaim with great excitement, 'frost cracking -- all of the paleo-ecological data suggests it had to be cold enough at Little Lake for frost cracking,'" said Marshall, now an NSF-supported postdoctoral researcher at the University of California, Berkeley. "And when the visual evidence in the core began to confirm our new hypothesis, it was exciting all over again."

Materials in the cores showed "a transition from finely laminated red, brown and gray lacustrine clay, silt and sands to coarse lacustrine blue-gray sand deposits" at about 26,000 years ago. Lacustrine soils are those found in fresh-water areas.

Subsequent analyses led by co-author Daniel Gavin, a professor in the UO geography department, found that the older sediment samples contained needles of both Sitka spruce and subalpine fir. This unusual combination of species, Gavin said, suggests a cold parkland setting characterized by patches of forest and open meadow such as that found in southeast Alaska today.

The distribution of such frosty conditions, Roering said, may have stretched from Oregon to Georgia, and efforts to prove that are already under way.

"Modern-day erosion and landscape change is slow compared to what it was during cold, dry climate intervals when there were no Douglas firs around and the hills were covered by grassy meadows," Roering said. "So using modern climate and geomorphic processes doesn't help us understand how much of our surroundings were created. Rock properties, soil thicknesses, everything that makes the Coast Range grow trees today all may be benefiting from soils produced during that frosty period. This is a humbling discovery."

The research at Little Lake also has helped answer questions raised by previous sediment samples taken from a different location near Little Lake. That work, led by former UO geographer Cathy L. Whitlock, now a professor of earth sciences at Montana State University, had focused on ancient pollen sources to study erosion and wildfire events. The difficulty in identifying spruce-related materials to the species level had implied colder average temperatures, ranging from 7 to 10 degrees Celsius, in the past; the latter is about 18 degrees Fahrenheit.

"This new research has totally reset my earlier perception of the Oregon Coast Range as a well-studied, well-characterized model landscape," Marshall said. "The implications go far beyond the Oregon Coast Range. I now believe we are much closer to being able to characterize just how the past glacial interval influenced -- and in some places continues to influence -- earth surface processes in regions that were never glaciated."


Story Source:

The above post is reprinted from materials provided by University of Oregon. Note: Materials may be edited for content and length.


Journal Reference:

  1. J. A. Marshall, J. J. Roering, P. J. Bartlein, D. G. Gavin, D. E. Granger, A. W. Rempel, S. J. Praskievicz, T. C. Hales. Frost for the trees: Did climate increase erosion in unglaciated landscapes during the late Pleistocene? Science Advances, 2015; 1 (10): e1500715 DOI: 10.1126/sciadv.1500715


University of Oregon. "Soil pulled from deep under Oregon's unglaciated Coast Range unveils frosty past climate: Landscapes across much of North America were colder, eroded rapidly from cracking frost during the last ice age, according to research." ScienceDaily. ScienceDaily, 27 November 2015. <www.sciencedaily.com/releases/2015/11/151127195110.htm>.

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Posted by: Lin Kerns <linkerns@gmail.com>



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[californiadisasters] On This Date In California Weather History (November 30)



2007: Heavy rain from cutoff low with a tropical connection produced up to 6" of rain at Palomar Mountain and Forest Falls on this day and on 12.1.
A debris flow (including large trees) over the Poomacha Burn area buried a house in mud, and caused serious damage to several vehicles and highway 76.
The flow was estimated at 15 feet high and 150 to 200 feet wide.

2004: Vallejo had a low temperature of 30° F.

1997: A waterspout was reported 6 miles south of Newport Beach.

1982: 26" of snow fell at Tahoe City, with 22" of snow reported at Truckee.

1982: A big storm that started on this day and ended on 12.1 brought widespread record rains and strong winds that knocked out power to 1.6 million homes.
1.96" of rain fell in LA on this day, a daily record.
On this day the LAX airport recorded a wind gust of 60 mph.

1972: Fresno had a high temperature of only 44° F, lowest on record for the month of November.

1970: A series of storms struck the region from 11.25 to this day following large destructive wildfires in the San Bernardino and San Gabriel Mountains earlier in the fall.
9.17" of precipitation fell in Lake Arrowhead, 7.22" in Lytle Creek, 5.11" in Big Bear Lake, 5.02" in Palomar Mountain, 3.56" in San Bernardino, 2.63" in Redlands, 2.51" in Santa Ana, and 2.05" in San Diego.
Flooding inundated streets and highways in the Rancho Cucamonga area.
At least 60 homes were damaged by floods and debris flows.
On this day a waterspout and three small funnel clouds were reported six miles west of San Diego.

1952: Heavy rain dropped almost 1" in Upland.
Street flooding was reported in Upland and homes were flooded in Ontario.

1932: Fresno received 0.3" of rain.
This is the latest occurrence of the first measurable rain of the water season on record.

1922: The morning low temperature at Reno was 8° F.

Source: NWS San Francisco/Monterey, Hanford, Reno, & San Diego

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Posted by: Kim Noyes <kimnoyes@gmail.com>


Be sure to check out our Links Section at http://groups.yahoo.com/group/californiadisasters/links
Please join our Discussion Group at http://groups.yahoo.com/group/californiadisasters_discussion/ for topical but extended discussions started here or for less topical but nonetheless relevant messages.





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Sunday, November 29, 2015

Re: [Geology2] SANDS OF TIME: The Earthquake of 1755



The Cape Ann Quake happened 2-1/2 weeks after the Lisbon Quake.... hmmmmmmmmmmm.


On Sun, Nov 29, 2015 at 4:22 PM, Lin Kerns linkerns@gmail.com [geology2] <geology2@yahoogroups.com> wrote:
 

  • SANDS OF TIME: The Earthquake of 1755
  • By Brett Robinson
    Co-curator, Pembroke Historical Society

    Posted Nov. 28, 2015

    Last week's minor earthquake near Holliston was notable not just for its rarity, but its timing. The ever so tiny 1.5-magnitude tremor came almost exactly 260 years after the most powerful earthquake to ever hit the eastern United States struck off of Cape Ann. The Holliston quake came around 8 p.m.on Nov. 17, 2015. The Cape Ann earthquake? November 18, 1755. 4 a.m.local time. Almost exactly 260 years.
Truly eerie.

And although there were no reports of shaking in Pembroke this time around, 260 years ago, our little town certainly felt like they were at the epicenter of the massive 6.0-magnitude earthquake that rattled the eastern seaboard. As Shelly Barclay of the Boston History Examiner wrote in a 2010 article about the 1755 quake, "[t]he Massachusetts towns of Pembroke, Lancaster and Scituate suffered cracks in the ground. In Pembroke, some of the cracks spewed water and sand." Truly scary stuff for folks not used to such shattering events!

Historian Sidney Perley includes the Great Earthquake of 1755 as one of his "Historic Storms of New England" because quite frankly, it really was a terrible storm for the unsuspecting people of the region. "People were in a state of extreme fright, thinking that the earth was in process of dissolution, and a writer of that time said, 'I walked out about sunrise, and every face looked ghastly.

In fine, some of our solid and pious gentlemen had such an awe and gloom spread over their countenances as would have checked the gay airs of the most intrepid.' It is said that in those regions where earthquakes are very common and to be expected, the people are terrorized by them, no familiarity with them removing the awful feeling.

No danger of alarm so disturbs a person, and no thought is so terrible as that of the earth crumbling to pieces beneath our feet. 'What is safe,' exclaimed the wise Seneca, 'if the solid earth itself cannot be relied upon?' This feeling disturbed the people of New England more than it would the inhabitants of tropical regions.

Animals were also alarmed at the mysterious and awful motions of the ground, and the oxen and cows lowed and hastened to the barns, the only source of protection that they knew, or ran about the fields when no place of refuge offered. Dogs went to their masters' doors and howled, not knowing what else to do; and birds left their perches, and flew into the air, fluttering there a long time, afraid to again alight on the earth.

The ocean along the coast was affected as perceptibly as the land, and ships in the harbor at Portsmouth, N.H., were shaken so fiercely that the sailors who were asleep in their berths were rudely awakened, their first thought being that they had struck upon a rock. The river there was also in a similar state of agitation.

"At New Haven, Conn., the ground moved with an undulating motion like the waves of the sea; and the houses shook and cracked as if about to fall. Mather Byles said, 'It was a terrible night, the most so, perhaps that ever New England saw.'

"The damage done by this earthquake was far greater than that caused by any other that has been experienced here. The vibratory motion of the earth was so great and sudden that pewter dishes were thrown from the dressers, many clocks were stopped, and the vane-rod on Faneuil hall in Boston, and those on some of the churches, were bent.
 
Much stone wall throughout the country was thrown down, and the shaking of the earth caused a change in the subterranean streams, in consequence of which many wells dried up. The principal damage consisted of the destruction of chimneys, no portion of New England being free from it. In Boston, alone, about one hundred were leveled with the roofs of the houses, and in all about fifteen hundred were shattered and partly thrown down, the streets in some places being almost covered with the fallen bricks. The chimneys were dislocated in all sorts of ways, some being broken several feet from the top, and partly turned as though there had been a swivel at the place. Others fell on the roofs, the sections broken off remaining intact, and having slipped down to the eaves jutted over, being just ready to fall. The roofs of some of the houses were broken in by the chimneys. The wooden buildings were much damaged by being racked, and many in Boston were thrown down.

Brick buildings were injured most; and in Boston the gable ends of twelve or fifteen were knocked down to the eaves. In spite of the great danger and many narrow escapes, no person or animal was killed or seriously injured."

Aftershocks continued for four more days, carrying on the great state of fear that had fallen over New England. But as with all earthquakes, those eventually subsided, and people returned to their regular routines, with a solid earth beneath their feet. That is, until Dec. 19, when two or three more aftershocks interrupted an otherwise calm evening. That was the last of it. But the folks of our region had been changed. "Educated and ignorant people alike were greatly frightened; and it is said that Rev. Mr. Richardson, then minister at Wells, Maine, died from fear at this time.

"The prospect of death turned the minds of the people toward those things that cannot be shaken, and the clergymen improved the opportunity to make a religious impression upon them. Many were led to reflect on the lives they had led, and to seek reconciliation with their Maker, the church membership being considerably increased."

Quotes and information for this column can be found at: Barclay, Shelly. "Cape Ann Earthquake in Boston: Part one." Boston History Examiner. August 30, 2010. http://www.examiner.com/article/cape-ann-earthquake-boston-part-one
Perley, Sidney. "Historic Storms of New England." The Salem Press Publishing and Printing Co. 1891.
http://pembroke.wickedlocal.com/article/20151128/NEWS/151127436




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Posted by: Kim Noyes <kimnoyes@gmail.com>



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Re: [Geology2] Earth not due for a geomagnetic flip in the near future



http://www.pbs.org/wgbh/nova/earth/when-our-magnetic-field-flips.html

Rick WA6NHC

Tiny iPhone keypad, spell check happens

On Nov 29, 2015, at 4:37 PM, Allison Maricelli-Loukanis allison.ann@att.net [geology2] <geology2@yahoogroups.com> wrote:

 

I will watch for it. Allison



On Saturday, November 28, 2015 12:21 AM, "Kim Noyes kimnoyes@gmail.com [geology2]" <geology2@yahoogroups.com> wrote:


 
A lot more of the Aurora Borealis and a bit more cancer. There is a great NOVA episode about this.

On Thu, Nov 26, 2015 at 10:31 AM, 'allison.ann@att.net' allison.ann@att.net [geology2] <geology2@yahoogroups.com> wrote:
 
Interesting but I'd like to know in practical terms what we would see in a magnetic pole flip. Allison

Sent from my Sprint phone.

----- Reply message -----
From: "Lin Kerns linkerns@gmail.com [geology2]" <geology2@yahoogroups.com>
To: <undisclosed-recipients:>
Subject: [Geology2] Earth not due for a geomagnetic flip in the near future
Date: Wed, Nov 25, 2015 8:02 AM

 
Public Release: 23-Nov-2015

Earth not due for a geomagnetic flip in the near future

Researchers find geomagnetic field intensity is double the long-term historical average
Massachusetts Institute of Technology
The intensity of Earth's geomagnetic field has been dropping for the past 200 years, at a rate that some scientists suspect may cause the field to bottom out in 2,000 years, temporarily leaving the planet unprotected against damaging charged particles from the sun. This drop in intensity is associated with periodic geomagnetic field reversals, in which the Earth's North and South magnetic poles flip polarity, and it could last for several thousand years before returning to a stable, shielding intensity.
With a weakened geomagnetic field, increased solar radiation might damage electronics -- from individual pacemakers to entire power grids -- and could induce genetic mutations. A reversal may also affect the navigation of animals that use Earth's magnetic field as an internal compass.
But according to a new MIT study in the Proceedings of the National Academy of Sciences, the geomagnetic field is not in danger of flipping anytime soon: The researchers calculated Earth's average, stable field intensity over the last 5 million years, and found that today's intensity is about twice that of the historical average.
This indicates that the current field intensity has a long way to fall before reaching an unstable level that would lead to a reversal.
"It makes a huge difference, knowing if today's field is a long-term average or is way above the long-term average," says lead author Huapei Wang, a postdoc in MIT's Department of Earth, Atmospheric and Planetary Sciences. "Now we know we are way above the unstable zone. Even if the [field intensity] is dropping, we still have a long buffer that we can comfortably rely on."
Flip-flopping through history
Earth has undergone multiple geomagnetic reversals over its lifetime, flip-flopping its polarity at random intervals.
"Sometimes you won't have a flip for about 40 million years; other times there will be 10 flips in 1 million years," Wang says. "On average, the duration between two flips is a few hundred thousand years. The last flip was around 780,000 years ago, so we are actually overdue for a flip."
The most obvious sign of an impending reversal is a geomagnetic field intensity that's significantly below its historical, long-term average -- a sign that the planet is tipping toward an unstable state. While satellites and ground-based observatories have made accurate measurements over the last 200 years of the current field intensity, there are less reliable estimates over the last few million years.
Wang and his colleagues, from Rutgers University and France, sought to measure Earth's paleomagnetic field using ancient rocks erupted from volcanoes on the Galapagos Islands -- an ideal site, since the island chain is on the equator. As Earth's magnetic field, in its stable configuration, is a dipole, the intensity of the field should be the same at both poles, and half that intensity at the equator.
Wang reasoned that knowing the paleomagnetic field intensity at the equator and the poles would therefore give an accurate estimate of the planet's average historical intensity.
Rocks from a dipole
Wang obtained samples of ancient volcanic lavas from the Galapagos, while his colleagues from the Scripps Institution of Oceanography at the University of California at San Diego excavated similarly aged rocks from Antarctica. Such volcanic rocks retain information on the geomagnetic field intensity at the time they cooled.
The two teams brought the samples back to their respective labs, and measured the rocks' natural remanent magnetization, or orientation of ferromagnetic particles. They then heated the rocks, and cooled them in the presence of a known magnetic field, measuring the rocks' magnetization after cooling.
A rock's remanent magnetization is proportional to the magnetic field in which it cooled. Therefore, using the data from their experiments, the researchers were able to calculate the peak distribution of the ancient geomagnetic field intensity, both at the equator -- about 15 microtesla -- and the poles -- about 30 microtesla. Today's field intensities at the same locations are around 30 microtesla and 60 microtesla, respectively -- double the historical, long-term values.
"That means today's value is anomalously high, and even if it's dropping, it's dropping to a long-term average, not from an average to zero," Wang says.
Far from zero
So why have scientists assumed that Earth's geomagnetic field is dropping to a precipitous low? It turns out this assumption is based on flawed historical data, Wang says.
Scientists have estimated paleomagnetic intensities at various latitudes around the Earth, but Wang's is the first data from equatorial regions. However, Wang found that scientists were misinterpreting how rocks recorded their magnetic fields, leading to inaccurate estimates of paleomagnetic intensity. Specifically, scientists were assuming that as individual ferromagnetic grains of rocks cooled, their unpaired electron spins assumed a uniform orientation, reflecting the magnetic field intensity.
However, this effect only holds true up to a certain size. In larger grains, unpaired electron spins assume various orientations in different domains of the grain, thereby complicating the field intensity picture.
Wang developed a method to correct for such multidomain effects, and applied the method to his Galapagos lavas. The results, he says, are more reliable than previous estimates of the paleomagnetic field.
As for when Earth may experience its next flip, Wang says the answer is still up in the air.
"What I can say is, if you keep a constant present-day decrease rate, it will take another 1,000 years for the field to drop to its long-term average," Wang says. "From there, the field intensity may go up again. There's really no way to predict what will happen after that, given the random nature of the magnetohydrodynamic process of the geodynamo."
http://www.eurekalert.org/pub_releases/2015-11/miot-end112315.php
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Posted by: "Rick Bates (WA6NHC)" <wa6nhc@gmail.com>



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Re: [Geology2] Earth not due for a geomagnetic flip in the near future



I will watch for it. Allison



On Saturday, November 28, 2015 12:21 AM, "Kim Noyes kimnoyes@gmail.com [geology2]" <geology2@yahoogroups.com> wrote:


 
A lot more of the Aurora Borealis and a bit more cancer. There is a great NOVA episode about this.

On Thu, Nov 26, 2015 at 10:31 AM, 'allison.ann@att.net' allison.ann@att.net [geology2] <geology2@yahoogroups.com> wrote:
 
Interesting but I'd like to know in practical terms what we would see in a magnetic pole flip. Allison

Sent from my Sprint phone.

----- Reply message -----
From: "Lin Kerns linkerns@gmail.com [geology2]" <geology2@yahoogroups.com>
To: <undisclosed-recipients:>
Subject: [Geology2] Earth not due for a geomagnetic flip in the near future
Date: Wed, Nov 25, 2015 8:02 AM

 
Public Release: 23-Nov-2015

Earth not due for a geomagnetic flip in the near future

Researchers find geomagnetic field intensity is double the long-term historical average
Massachusetts Institute of Technology
The intensity of Earth's geomagnetic field has been dropping for the past 200 years, at a rate that some scientists suspect may cause the field to bottom out in 2,000 years, temporarily leaving the planet unprotected against damaging charged particles from the sun. This drop in intensity is associated with periodic geomagnetic field reversals, in which the Earth's North and South magnetic poles flip polarity, and it could last for several thousand years before returning to a stable, shielding intensity.
With a weakened geomagnetic field, increased solar radiation might damage electronics -- from individual pacemakers to entire power grids -- and could induce genetic mutations. A reversal may also affect the navigation of animals that use Earth's magnetic field as an internal compass.
But according to a new MIT study in the Proceedings of the National Academy of Sciences, the geomagnetic field is not in danger of flipping anytime soon: The researchers calculated Earth's average, stable field intensity over the last 5 million years, and found that today's intensity is about twice that of the historical average.
This indicates that the current field intensity has a long way to fall before reaching an unstable level that would lead to a reversal.
"It makes a huge difference, knowing if today's field is a long-term average or is way above the long-term average," says lead author Huapei Wang, a postdoc in MIT's Department of Earth, Atmospheric and Planetary Sciences. "Now we know we are way above the unstable zone. Even if the [field intensity] is dropping, we still have a long buffer that we can comfortably rely on."
Flip-flopping through history
Earth has undergone multiple geomagnetic reversals over its lifetime, flip-flopping its polarity at random intervals.
"Sometimes you won't have a flip for about 40 million years; other times there will be 10 flips in 1 million years," Wang says. "On average, the duration between two flips is a few hundred thousand years. The last flip was around 780,000 years ago, so we are actually overdue for a flip."
The most obvious sign of an impending reversal is a geomagnetic field intensity that's significantly below its historical, long-term average -- a sign that the planet is tipping toward an unstable state. While satellites and ground-based observatories have made accurate measurements over the last 200 years of the current field intensity, there are less reliable estimates over the last few million years.
Wang and his colleagues, from Rutgers University and France, sought to measure Earth's paleomagnetic field using ancient rocks erupted from volcanoes on the Galapagos Islands -- an ideal site, since the island chain is on the equator. As Earth's magnetic field, in its stable configuration, is a dipole, the intensity of the field should be the same at both poles, and half that intensity at the equator.
Wang reasoned that knowing the paleomagnetic field intensity at the equator and the poles would therefore give an accurate estimate of the planet's average historical intensity.
Rocks from a dipole
Wang obtained samples of ancient volcanic lavas from the Galapagos, while his colleagues from the Scripps Institution of Oceanography at the University of California at San Diego excavated similarly aged rocks from Antarctica. Such volcanic rocks retain information on the geomagnetic field intensity at the time they cooled.
The two teams brought the samples back to their respective labs, and measured the rocks' natural remanent magnetization, or orientation of ferromagnetic particles. They then heated the rocks, and cooled them in the presence of a known magnetic field, measuring the rocks' magnetization after cooling.
A rock's remanent magnetization is proportional to the magnetic field in which it cooled. Therefore, using the data from their experiments, the researchers were able to calculate the peak distribution of the ancient geomagnetic field intensity, both at the equator -- about 15 microtesla -- and the poles -- about 30 microtesla. Today's field intensities at the same locations are around 30 microtesla and 60 microtesla, respectively -- double the historical, long-term values.
"That means today's value is anomalously high, and even if it's dropping, it's dropping to a long-term average, not from an average to zero," Wang says.
Far from zero
So why have scientists assumed that Earth's geomagnetic field is dropping to a precipitous low? It turns out this assumption is based on flawed historical data, Wang says.
Scientists have estimated paleomagnetic intensities at various latitudes around the Earth, but Wang's is the first data from equatorial regions. However, Wang found that scientists were misinterpreting how rocks recorded their magnetic fields, leading to inaccurate estimates of paleomagnetic intensity. Specifically, scientists were assuming that as individual ferromagnetic grains of rocks cooled, their unpaired electron spins assumed a uniform orientation, reflecting the magnetic field intensity.
However, this effect only holds true up to a certain size. In larger grains, unpaired electron spins assume various orientations in different domains of the grain, thereby complicating the field intensity picture.
Wang developed a method to correct for such multidomain effects, and applied the method to his Galapagos lavas. The results, he says, are more reliable than previous estimates of the paleomagnetic field.
As for when Earth may experience its next flip, Wang says the answer is still up in the air.
"What I can say is, if you keep a constant present-day decrease rate, it will take another 1,000 years for the field to drop to its long-term average," Wang says. "From there, the field intensity may go up again. There's really no way to predict what will happen after that, given the random nature of the magnetohydrodynamic process of the geodynamo."
http://www.eurekalert.org/pub_releases/2015-11/miot-end112315.php
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Posted by: Allison Maricelli-Loukanis <allison.ann@att.net>



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