Stories tagged Earth Structure and Processes
Tags : Strong magnitude 6.1 aftershock hits Haiti
Haiti aftershock earthquakeCourtesy American Red Cross
A strong aftershock rocked Haiti on Wednesday morning just as much-needed medical aid was set to reach the earthquake-ravaged nation.
The 6.1-magnitude aftershock was about 6.2 miles deep, with an epicenter about 35 miles (60 kilometers) west-southwest of the capital of Port-au-Prince, the U.S. Geological Survey said. CNN
Learn more about Haiti earthquake news
- CNN has a comprehensive page about the Haiti earthquake here.
- For CNN's up to the minute Haiti earthquake developments click here.
A satellite image of the East Siberian Sea from USGSCourtesy United States Geological SurveyWhen I read this story the other day, I thought to myself: why didn't I think of that? Or maybe I did think of it, but as usual no one was listening when I pitched the idea for an action-packed spy movie about climate change. Or were they?
The Central Intelligence Agency does have a bunch of high-powered satellites and other "classified" instruments, so it's possible they've been using them to eavesdrop on my conversations with friends about possible sci-fi movie plots.
What's more likely: they figured out on their own that intelligence-gathering instruments could be really helpful to scientists, who can read detailed pictures of melting sea ice, growing desserts and other phenomena to better understand how climate is changing the planet.
The C.I.A. recently confirmed that it had revived this controversial data-sharing program known as Madea, which stands for Measurements of Earth Data for Environmental Analysis. If you decode that C.I.A. code name, it means that government spies are working with climate scientists to gather images and data about environmental change, as well as its impact on human populations.
Not everyone is convinced that climate change is a real threat to national security, and so some complainers are complaining that this collaboration between scientists and the C.I.A. is a misuse of resources, but what do they know?
Really? What do they know? So much of what happens over at C.I.A. headquarters is top-secret.
Maybe the whole thing doesn't sound that action packed, but I'm telling you, if you had the right actors playing the scientists, it could be a blockbuster. And if you have the right scientists analyzing the data, it might provide really valuable insights into global environmental change.
GOCE Satellite: The Gravity field and steady-state Ocean Circulation ExplorerCourtesy ESACan it be true? Yes, for a mere $5,544 dollars round-trip airfare to Greenland! In March 2009, the European Space Agency launched the Gravity field and steady-state Ocean Circulation Explorer (GOCE) into orbit around our planet, which is now transmitting detailed data about the Earth’s gravity. The GOCE satellite uses a gradiometer to map tiny variations in the Earth’s gravity caused by the planet’s rotation, mountains, ocean trenches, and interior density. New maps illustrating gravity gradients on the Earth are being produced from the information beamed back from GOCE. Preliminary data suggests that there is a negative shift in gravity in the northeastern region of Greenland where the Earth’s tug is a little less, which means you might weigh a fraction of a pound lighter there (a very small fraction, so it may not be worth the plane fare)!
In America, NASA and Stanford University are also working on the gravity issue. Gravity Probe B (GP-B) is a satellite orbiting 642 km (400 miles) above the Earth and uses four gyroscopes and a telescope to measure two physical effects of Einstein’s Theory of General Relativity on the Earth: the Geodetic Effect, which is the amount the earth warps its spacetime, and the Frame-Dragging Effect, the amount of spacetime the earth drags with it as it rotates. (Spacetime is the combination of the three dimensions of space with the one dimension of time into a mathematical model.)
Quick overview time. The Theory of General Relativity is simply defined as: matter telling spacetime how to curve, and curved spacetime telling matter how to move. Imagine that the Earth (matter) is a bowling ball and spacetime is a trampoline. If you place the bowling ball in the center of the trampoline it stretches the trampoline down. Matter (the bowling ball) curves or distorts the spacetime (trampoline). Now toss a smaller ball, like a marble, onto the trampoline. Naturally, it will roll towards the bowling ball, but the bowling ball isn’t ‘attracting’ the marble, the path or movement of the marble towards the center is affected by the deformed shape of the trampoline. The spacetime (trampoline) is telling the matter (marble) how to move. This is different than Newton’s theory of gravity, which implies that the earth is attracting or pulling objects towards it in a straight line. Of course, this is just a simplified explanation; the real physics can be more complicated because of other factors like acceleration.
Albert EinsteinCourtesy noneSo what is the point of all this high-tech gravity testing? First of all, our current understanding of the structure of the universe and the motion of matter is based on Albert Einstein’s Theory of General Relativity; elaborate concepts and mathematical equations conceived by a genius long before we had the technology to directly test them for accuracy. The Theory of General Relativity is the cornerstone of modern physics, used to describe the universe and everything in it, and yet it is the least tested of Einstein’s amazing theories. Testing the Frame-Dragging Effect is particularly exciting for physicists because they can use the data about the Earth’s influence on spacetime to measure the properties of black holes and quasars.
Second, the data from the GOCE satellite will help accurately measure the real acceleration due to gravity on the earth, which can vary from 9.78 to 9.83 meters per second squared around the planet. This will help scientists analyze ocean circulation and sea level changes, which are influenced by our climate and climate change. The information that the GOCE beams back will also assist researchers studying geological processes such as earthquakes and volcanoes.
So, as I gobble down another mouthful of leftover turkey and mashed potatoes, I can feel confident that my holiday weight gain and the structure of the universe are of grave importance to the physicists of the world!
Floating Free on the Dead SeaCourtesy Courtesy of Ranveig at Wikimedia CommonsIn anticipation for the Dead Sea Scrolls exhibit coming to the Science Museum of Minnesota, I found myself wondering, why do we call it the Dead Sea? The Dead Sea is the lowest place on earth and one of the saltiest bodies of water in the world, 6 to 10 times saltier than the Atlantic Ocean. Because the salt creates such a harsh living environment, the only organisms that will survive in the Dead Sea are bacteria and algae. Any fish that accidentally swims into the Dead Sea from one of the freshwater streams that feed it, like the Jordan River, would die instantly!
The sea is so salty because of evaporation. The high temperatures and low humidity in the region cause the water in the sea to evaporate very quickly, leaving behind all the dissolved mineral salts. Some salts sink to the bottom and some wash ashore leaving a salty crusty beach.
Dead Sea Salt BeachCourtesy Courtesy of Isewell at WikiMedia Commons
Because of the high concentration of mineral salts in the Dead Sea, the water is more dense than both freshwater and the human body. This means that our bodies become buoyant, like a cork, and we can easily float on it. When you take a dip in the Dead Sea you can actually kick back and read a book like floating on a raft. In fact, it is hard to actually “swim” in the sea.
Dead Sea SaltCourtesy Courtesy of Xtall at WikiMedia Commons
The Dead Sea has been a tourist attraction since the time of Herod the Great in the 1st Century BCE. The Dead Sea isn’t just a novelty for “fun while floating” but the mineral salts have been used in Egyptian mummification, in agricultural fertilizers and even in modern day cosmetics. Check out these links to learn more about Dead Sea geography, how it was formed, how it is used by humans, and some of the issues it faces today.
http://www.extremescience.com/DeadSea.htm
http://www.wysinfo.com/Dead_Sea/dead_sea_overview.html
Trailhead signCourtesy Mark RyanIn the latter days of summer my wife and I took a drive up the Gunflint Trail and visited the Magnetic Rock Trail, a spur trail jutting off the Gunflint near Gunflint Lake. Our original plans of lounging about the North Shore of Lake Superior had been scuttled by a mix-up in our cabin reservations, so I saw it as an opportunity to check out first-hand some of the local geology. I had visited the MRT briefly once before and my reasons for wanting to make the 50-mile drive from Grand Marais to revisit the trail were three-fold: stromatolites, meteorite impact ejecta, and, of course, magnetic rocks
Well, as it turns out, I wasn’t very successful,
Signs of recent fire: Evidence of forest fire can still be seen along the Magnetic Rock Trail.Courtesy Mark RyanReaders may recall the Ham Lake forest fires raged along the Gunflint Trail in the early summer of 2007, destroying several hundred acres of the surrounding forest along with resorts and private property. The fire, it was later determined, was started by a legal campfire in the vicinity of Ham Lake that had gotten out of hand and spread quickly through the region. It was the second forest fire to rage through the Magnetic Rock Trail (MRT) in the past two decades (there was also a controlled burn in 2002). The latest fire removed much of the pine canopy that covered the area, opening it to more sky and sunlight, and new vistas of the surrounding terrain.
Idyllic scene at a pond along the Magnetic Rock TrailCourtesy Mark Ryan
A new jack pine rises from the ashesCourtesy Mark RyanBut as destructive as forest fires can be, they do have their upside. Forests are quick to revitalize after fires. New trees soon rise up from the ashes, and evidence of that in the MRT was apparent in the many jack pines (Pinus banksiana) we saw sprouting up everywhere. But trees aren’t the only affected flora. A lot of the groundcover gets incinerated as well, sometimes exposing patches of bedrock. In the case of the Magnetic Rock Trail, it meant new outcrops of the Gunflint Iron Formation were uncovered, revealing fresh unexplored exposures.
The Gunflint Iron Formation is a mass of iron ore taconite that spans from the Arrowhead region of Minnesota eastward into Ontario, Canada with the majority of the formation located on the Canadian side of the border. Most iron formations on Earth were formed around the same time, about 2 billion years ago during the Middle Pre-Cambrian (Early Proterozoic) times. A shallow sea (the Animikie) covered much of northern Minnesota and eastern Ontario at the time. The sea teemed with cyanobacteria in the form of stromatolites; thick microbial mats that helped oxygenate the Earth’s atmosphere and metabolize iron out of solution through photosynthesis. The iron-oxide sediments later became the iron ranges that span across northern Minnesota and Canada. Much of the rock along the Magnetic Rock Trail is composed of magnetite (Fe3 O4) inter-bedded with layers of chert or shale. Magnetite is the most magnetic of all the naturally occurring minerals, hence its name. The Gunflint Iron Formation is particularly resistant to erosion on the Minnesota side probably due to its nearness to the Duluth Complex intrusives. These influxes of magma moved into the area around 1.1 billion years ago, adding tremendous heat to the existing strata. The portion of the Gunflint Iron Formations (that located in Minnesota) closest to the heat source shows the most resistance to erosion.
Stromatolites and not?: Stromatolites by geologist Jim Miller, MN Geological Survey (top); maybe not stromatolites by author (bottom)Courtesy Jim Miller, MN Geological Survey (top) Mark Ryan (bottom)Preserved within some of the newly exposed outcrops along the MRT are fossil records of these stromatolites, representing some of the oldest fossils found in Minnesota. Gunflint stromatolites contain large numbers of fossils that can be seen under a scanning electron microscope. I had been told that you can walk off the main path and find some of these ancient fossils, so I searched off-trail for a while and found what I thought were stromatolites, and took photos of them.
But later when I consulted with geologist Mark Jirsa, he wasn’t so sure.
“You're looking at thin bedding in the iron formation that dips shallowly in comparison to the dip of the outcrop surface,” he wrote me. “The result is a swirly look, that looks deceptively like stromatolite mounds.”
Jirsa was in the field when I contacted him, and his Internet capability was limited, so when he tried to send me some photos of what the stromatolites actually looked like, they didn’t come through. However, his colleague, geologist Jim Miller (who also supplied welcomed assistance with this post) sent me a stromatolite photo he had taken at MRT.
Personally, I can’t tell the difference, but then I’m no geologist. so I have to bow to the professionals.
My second quest – to locate and photograph ejecta from the Sudbury Impact – wasn’t successful either. The aforementioned Mark Jirsa discovered this record of a 1.85 billion-year-old meteor impact in 2007. I wrote a previous post about it that same year so I won’t go into those details (you can read it here) but I will bring you up to speed on how he’s since interpreted the find.
Briefly, the Sudbury Impact Crater is located in Ontario, Canada, and was made by a meteorite about 10-miles in diameter that slammed into the Earth 1.85 million years ago. The 150-mile wide crater is the second largest known on the planet. The collision sent a tremendous firestorm of superheated material into the atmosphere, and some of it coalesced like hailstones and landed 480 miles away in northeastern Minnesota. This is what Jirsa discovered two years ago: a layer of ejecta mixed with torn up pieces (breccia ) of the Gunflint Formation, and all of it overlain by a younger layer of slate known as the Rove Formation. He published an article about it in Astronomy magazine, and there’s also a PDF file downloadable from Minnesota Geological Survey website (the link is located in the upper left of the MGS homepage).
Debris from Sudbury Impact found in Minnesota: Photo by Mark Jirsa, Minnesota Geological SurveyWhat Jirsa found was quite remarkable: a layer of churned-up rocks laid down above the Gunflint Iron Formation. The odd jumble of rock included berry-shaped rocks known as accretionary lapilli, intermixed with the Gunflint Iron Formation rock. According to his interpretation, what is seen in the layer essentially shows the events of a single day in the geological record. And a nasty day it must have been.
Three minutes after the initial fireball impact at Sudbury, seismic waves from earthquakes measuring more than magnitude-10 on the Richter Scale reached the Animikie basin, ripping loose the iron formation off the seafloor crust, and redistributed it along a submarine slope. Within 10 minutes, a firestorm of molten material hailed down from the sky covering the region with from 3 to 10 feet of ejecta in the form of accretionary lapilli. Ultra-hurricane-force winds measuring up to 1400 mph(!) blasted over the shallow sea soon after, followed by the coup de grace – titanic tsunamis the likes of which have never been seen since which tossed everything into a stew of breccia (jumbled rock) and berry-shaped ejecta.
This day of horror took place sometime in the 48 million year interim that separates the Gunflint Iron Formation and the time the sediments of the Rove Formation were laid down above it. The entire concoction was later baked and metamorphosed by the intrusive magmas of the Duluth Complex.
How hard could it be to find evidence of a mess like this? Well, considering the MRT covers a large area, and since I had no information pinpointing any locations, it was like looking for a needle in a haystack – a very large haystack. In the end, I soon gave up because I really didn’t know what I was looking for and I realized how futile it probably would be. However, I’ve sure learned a whole lot about it now.
Magnetic Rock Trail's rocks are magnetic: as my handy magnet proves.Courtesy Mark RyanInitially, I thought at least my third quest – finding magnetic rock – would be a complete success because just about every rock exposed along the MRT is highly magnetic (I had a magnet with me and I can attest to that fact – see photo). It made sense that the whole reason the trail is called the Magnetic Rock Trail is because of all the magnetic rocks found there. But I’ve since learned I was once again totally wrong. The trail is name after a single large magnetic rock that’s about 1.5 miles up the trail. This 30-foot monolith stands upright and obvious in the middle of the forest and its notoriety dates back to early native American times. It is a chunk of the Gunflint Iron Formation – and highly magnetic like the rest of the rock in the area – but is deemed an erratic moved into place from a short distance away by glaciers during the last Ice Age. Had I read any of the brochures I had collected on our trip sometime other than when I got home, I would have known this before I even got there. But as it was, we didn’t walk that far into the trail so we missed it completely. Oh, well.
Blueberry picking: Mrs. R collects blueberries near the Magnetic Rock Trail.Courtesy Mark RyanBut even though my three main objectives for visiting the MRT were pretty much complete washouts, there was one unexpected surprise that will probably draw us back to the region next year: blueberries.
Blueberries and metamorphism: The real attraction at the Magnetic Rock Trail?Courtesy Mark RyanWild blueberries (Vaccinium angustifolium) were all over the place. The low-bush berries thrive in sandy, acid soils of forest clearings, and in rocky areas around pines forests – just the type of environments you find around the MRT. So, once I finished with my failed geological studies, I assisted my wife in picking as many wild blueberries as we needed. We kept them in our cooler for the ride home, and as Mrs. R is prone to do, she jumbled all the berries together into a viscous concoction, all within a flakey crust that was heated over time at a very high-temperature.
The result looked something like the Sudbury Impact ejecta layer found near the Magnetic Rock Trail, but it was much more delicious, and a great way to end the summer.
ADDITIONAL LINKS
Forest regrowth on Buzz
More about stromatolites
Top Ten Most Impressive Impact Craters
More about Minnesota geology
Anza-Borrego Desert State ParkCourtesy California State ParksThe National Center for Earth-surface Dynamics or NCED is based at St. Anthony Falls Laboratory at the University of Minnesota. Partners of the center include colleges, universities, and education centers from across the United States one of which is the Science Museum of Minnesota (SMM).
In their work, NCED wants to predict the dynamics and evolution of a landscape in order to better understand how to manage and restore the Earth-surface environment. They do this by modeling the evolution of the landscape and its ecosystem, studying the depositional systems in river deltas, and working on new research and tools for stream restoration. NCED programs that do this research include Desktop Watersheds, Subsurface Architecture, and Stream Restoration.
Education is a big part of what the center provides. You can see some of their work right here at SMM in the Big Back Yard exhibit where you can get a first hand look at some of the earth’s surfaces and learn how they were made. Water plays a big part in how the earth surfaces are formed and you can learn more about it in the exhibit Water:H2O=Life which is a collaboration of work of several groups and museums that is now traveling.
So go and explore what is shaping this earth and how NCED is helping in the understanding and revival of the earth’s surfaces.
Mouth of the Columbia RiverCourtesy U.S. Army Corps of Engineers Digital Visual LibraryHave you ever wondered what happens when a river ends and the ocean begins? Well, the scientists at the Center for Coastal Margin Observation and Prediction (CMOP) do. Based out of Oregon, the center conducts their research on the Columbia River. Their goal is to understand and predict how humans and the climate affect the costal margins. The research has three themes, to test and advance the way research is done, to understand the human and natural variables that affect the margin, and to integrate the two previous themes to create a functional research station.
So, are you still contemplating the question, what is going on in this unique area where fresh water that has travel the country meets the salty water of the ocean? Well, the center has opportunities for K-12 students and teachers and undergrad and graduate students to become involved. Everything from summer camps and programs for middle and high school students to internships for the undergrad and grad students. Not interested in traveling? Data is also available on their website for the free-lance researcher.
Before the next time you jump into the big blue, quench your thirst for knowledge and see what CMOP is doing to research and preserve the coastal margins of the Columbia.
Earth MessengerCourtesy NASA
NASA's Earth Observatory is celebrating its 10th anniversary this year and in that time is has given scientist and the general pubic a new view on the earth and how it is changing. The Earth Observatory site has satellite images of events on the earth ranging from storms and climate change to the growth of cities. The images are not only interesting to look at but they have helped scientist research the changing of seasons, snow caps, and cloud patterns in a whole new way. With growing popularity the images are also being sought out by other agencies, for example when the coast of Louisiana was hit by a hurricane the images were used to get a clearer picture of the flooding in the cities. Check out their archives, you will see awesome pictures and learn something new about the planet we live on.
A tsunami of New Yorkers head for the highlands.: Would the evacuation be this organized?Courtesy Pabo76What say we take a breather from all the bleak and uncertain flu news and turn our collective attention to the possibility of a tsunami washing away the East Coast of the USA? Fortunately no such threat is on the horizon at the present moment but scientists have found evidence they say indicates a large tsunami hit areas of New York and New Jersey some 2300 years ago.
The evidence includes large gravel, wood deposits, and marine fossils found in core samples across the region dating to 300BC, and suggests some sort of violent event took place in the region. The size and condition of some of the deposits point to strong reworking of material rather than just a single violent storm. The wave is estimated to have been 9 to 12 feet in height with the velocity of the water estimated at about a meter per second. If a similar tsunami hit Manhattan today no doubt there’d be big trouble.
But Atlantic tsunamis are rare events. Unlike the Pacific and Indian oceans where tectonic plates are colliding and earthquakes are more common, the plates along the Atlantic ridge are spreading apart. That’s not to say an Atlantic tsunami isn’t possible today. In 1929, a tsunami swept into the coast of Newfoundland killing more than two dozen people. The cause was a massive underwater landslide triggered by a 7.2 magnitude earthquake on the Grand Banks.
But neither an earthquake nor a submarine slump may have been involved in the 300BC tsunami. Recent research indicates an asteroid impact somewhere off the Atlantic coast dating to about the same time. Ejecta found in the local sediments such as spherules, shocked quartz, and nanodiamonds could only have been created under extreme temperatures and pressures produced by an extraterrestrial. No crater has been located as of yet but the scientists continue searching.
LINKS
BBC ancient tsunami story
More about the 300BC tsunami
East Coast tsunami threat considered in 2004
