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for October, 2010.
Welcome to The Deep science and technology column where we cover topics from the deep sea to deep space and beyond.
Living as we do in the ring of fire, earthquakes are a part of our lives. As one of the perks of the Internet, I subscribe to a service of the US Geological Service (USGS) called “Big Quake”. I get e-mails when there are big quakes anywhere in the world. I knew about the quake that generated the Boxing Day tsunami long before the tsunami waves hit the coast of Africa. This morning, I received an e-mail that said there had been a 4.6 earthquake in Wyoming. “That’s odd” I thought, earthquakes are uncommon in the continental US. Then I remembered what’s in the northwestern corner of Wyoming and I realized it was time to dip into the geology folder.
GEYSERS, GLORY HOLES AND EARTHQUAKES, OH MY!
What’s in the northwestern corner of Wyoming is the oldest national park, the home of Smokey the Bear, Yellowstone National Park. You’ve all heard of it and some of you may have even been there. Old Faithful Geyser, all those bears, all that gorgeous scenery.
In the ‘60’s and ‘70’s, a glory time for geology, we realized that most volcanoes and earthquakes occur where two plates collide. That’s what causes ours, that’s what causes the ones in Indonesia, Alaska, California, Chili and indeed that’s the cause of most of the world’s seismic activity. But there are no plates at Yellowstone. So where was all that heat and steam coming from?
For that matter, where did the huge lava flows come from in the area? Slowly, it began to dawn on geologists that Yellowstone National Park wasn’t just a beautiful and slightly strange location. Yellowstone National Park is the mouth of one of Earth’s largest volcanoes. And, it’s still active.
The University of Utah has seismograph stations all over Yellowstone and there has been a notable swarm of earthquakes going on at Yellowstone for almost two years now. We’re talking thousands of earthquakes, most of them too small to feel, although there have been bigger ones than yesterday’s 4.6.
They’re concentrated under Yellowstone Lake which apparently fills the mouth of the Yellowstone Volcano caldera. This many earthquakes means that there’s a considerable amount of magma movement down there somewhere and the geologists are keeping a close eye on the activity.
Earthquakes are common in the Yellowstone National Park area, averaging 1,000 to 2,000 earthquakes a year. Yellowstone’s 10,000 geysers and hot springs are the result of this geologic activity but this latest upswing in activity has the geologists scratching their heads.
Yellowstone had erupted about every million years or so and we’re still 90,000 years from the average time between eruptions. But volcanic eruptions are notoriously unpredictable, especially when we’re talking a bad boy the size of Yellowstone.
The eruption, when it comes, will probably be a simple upswing in the ‘leakage’ that’s already occurring. More vents, more geysers, more hot springs. But Yellowstone has ERUPTED at least three times in the last several million years and the lava, ash and other consequences covered most of the continental US. There would no doubt be global effects of a massive Yellowstone eruption. You do NOT want it to happen in your lifetime!
So, even with the current upswing in activity, here’s hoping Yellowstone stays as the geologic wonder it is for a very long time!
Old Faithful Geyser in Yellowstone National Park, U.S. (Credit: iStockphoto/Yenwen Lu)
As many of you know, Yellowstone isn’t the only anomalous earthquake site in the US. The strongest earthquake ever to hit the mainland didn’t happen at Yellowstone or in California. It happened in the early 1800’s . . . in Missouri.
I grew up in Missouri and I grew up with earthquakes. They were never very big, not like the ones we get here, but we did have them. Now, new research shows that most of the earthquakes like the ones that shook up my youth, are aftershocks of the New Madrid earthquakes that struck the Midwest almost 200 years ago. The New Madrid earthquakes were all over magnitude 7.
The study’s lead author says that all the aftershocks are very unusual. Typically you only get aftershocks from earthquakes for around 10 years, not 200. But they apparently continue for much longer when they occur in the middle of a continent.
The reason? According to the article, "Aftershocks happen after a big earthquake because the movement on the fault changed the forces in the earth that act on the fault itself and nearby. Aftershocks go on until the fault recovers, which takes much longer in the middle of a continent."
The difference occurs because of speed. The two sides of the San Andreas Fault move past each other at a speed of about one and a half inches in a year: fast on a geologic time scale. This motion "reloads" the fault by swamping the small changes caused by the last big earthquake, so aftershocks are suppressed after about 10 years. The New Madrid faults, however, move more than 100 times more slowly, so it takes hundreds of years to swamp the effects of a big earthquake.
The geologists suspected this was the case because the earthquakes in the Midwest have patterns that look like aftershocks. They occur on the faults that caused the big earthquakes in 1811 and 1812, and they’ve been getting smaller with time.
To test this idea, the researchers used results from lab experiments on how faults in rocks work to predict that aftershocks would extend much longer on slower moving faults. They looked at data from faults around the world and found the expected pattern. For example, aftershocks continue today from the magnitude 7.2 Hebgen Lake earthquake that shook Montana, Idaho and Wyoming 50 years ago.
This makes sense because the Hebgen Lake fault moves faster than the New Madrid faults but slower than the San Andreas. Aftershocks go on for long times in other places inside continents. Small earthquakes continue today in the area along Canada’s Saint Lawrence valley where a large earthquake occurred in 1663.
The new results will help investigators to both understand earthquakes in continents and to assess earthquake hazards there. In the past geologists have basically tried to predict where large earthquakes will happen by looking at where small ones do. This didn’t work for the disastrous May 2008 magnitude 7.9 earthquake in Sichuan, China because there hadn’t been any earthquakes in the area in several few hundred years.
The researchers say that now they know that big earthquakes can happen in unlikely places so instead of just focusing on where small earthquakes happen, they need to use methods like GPS satellites and computer modeling to look for places where the earth is storing up energy for a large future earthquake. They don’t see that in the Midwest today, but they will keep looking.
So . . . that may explain why there are still earthquakes in Missouri today, but it doesn’t explain what caused the New Madrid quakes to begin with. Researchers at Purdue University may have just solved that little riddle.
The new theory suggests that the energy necessary to produce the magnitude 7-7.5 earthquakes New Madrid earthquakes came from stored stress built up in the Earth’s crust long ago. Rapid erosion from the Mississippi River at the end of the last ice age reduced the forces that had kept the New Madrid fault from slipping and triggered the quakes.
Eric Calais, the Purdue professor of earth and atmospheric sciences who led the study, said the theory is the first to explain how a fault could have produced large earthquakes in the recent past but show no signs of accumulating the forces needed to produce another earthquake.
Calais and others analyzed the fault for more than 10 years using GPS measurements to study movements of the Earth’s surface that represent a buildup of energy. These movements have traditionally been used to evaluate the potential for an earthquake. Their data showed that no such motion is occurring along the New Madrid fault.
If there’s no deformation occurring along the fault today, where did the energy to produce the earthquakes come from?
Andrew Freed, co-author of the paper and an associate professor of earth and atmospheric sciences at Purdue, says, "The only way to reconcile the fact that this part of the continent is not deforming but is producing earthquakes is that the stresses built up long ago. Old geologic processes, like the opening of the Atlantic and the uplift of the Rocky Mountains, may have squeezed the Midwest. The resulting stress remained stored for millions of years until uplift associated with the Mississippi erosion event led to the unclamping of old faults lying beneath."
The New Madrid fault may also be the result of rebound from the ice sheet that covered North America in the last Ice Age. For a period from 16,000 to 10,000 years ago as the ice sheet melted, the water flowed down the Mississippi River washing away sediments and removing millions of tons of rocks and dirt. When this weight was removed, the crust rebounded and bulged slightly up from its previous position. The arching caused the top layers of Earth’s crust to be stretched and the bottom layers to be compacted, exerting force on the preexisting faults. This force was eventually released in the New Madrid region, culminating with the 1811-1812 earthquakes.
How much stress is left? Nobody knows! There’s a lot that goes on down there that we don’t know about! But try not to get too shook up about it!
Welcome to The Deep science and technology column where we cover topics from the deep sea to deep space and beyond.
Even as the northern hemisphere slides into winter (you’ve noticed that it’s getting colder and the leaves are changing color, right?) it’s time to talk about not cold but heat. Global warming just won’t go away and we’re going to talk this week about some of the changes that the warming weather is causing all over the Earth.
LEARNING FROM THE EXPERTS
First we’ll take a little trip to NOAA and see what they have to say about the current state of the planet’s temperatures. According to their website, the first nine months of 2010 tied with the same period in 1998 for the warmest combined land and ocean surface temperature on record. The global average land surface temperature for January-September was the second warmest on record, behind 2007. The global ocean surface temperature for January–September was also the second warmest on record, behind 1998.
The monthly analysis from NOAA’s National Climatic Data Center, which is based on records going back to 1880, is part of the suite of climate services NOAA provides government, business and community leaders, so they can make informed decisions.
Global Temperature Highlights
· For the year-to-date, the global combined land and ocean surface temperature of 58.67 F tied with 1998 as the warmest January-September period on record. This value is 1.17 F above the 20th century average.
· The combined global land and ocean average surface temperature for September 2010 tied with 1998 as the eighth warmest on record at 59.9 F, which is 0.9 F above the 20th century average of 59.0 F.
· Separately, the September global land surface temperature was 1.19 F above the 20th century average of 53.6 F — the ninth warmest September on record. Warmer-than-average conditions dominated the world’s land areas. The most prominent warmth was in western Alaska, most of the contiguous United States, eastern Canada, Greenland, the Middle East, eastern and central Europe, western and far eastern Russia and northeastern Asia. Cooler-than-average regions included much of Australia, western Canada, parts of the northern United States, parts of western and central Europe, and central Russia.
· According to NOAA’s National Weather Service, Los Angeles set a new all-time maximum temperature on Sept. 27 when temperatures soared to 113 F, surpassing the previous record of 112 F set in June 1990.
· The worldwide ocean surface temperature was 0.79 F above the 20th century average of 61.1 F (16.2 C) and the ninth warmest September on record. The warmth was most pronounced in the Atlantic Ocean and the western Pacific Ocean.
Polar Sea Ice and Precipitation Highlights
· Arctic sea ice reached its annual minimum on Sept. 19, according to the National Snow and Ice Data Center. The average extent of 1.89 million square miles was the third lowest September sea ice extent on record (30.4 percent below average). The annual record was set in 2007 (38.9 percent below average). This year also marked the 14th consecutive September with below-average Arctic sea ice extent.
· Antarctic sea ice reached its annual maximum in September. September 2010 was the third largest sea ice extent on record (2.3 percent above average), behind 2006 (largest) and 2007 (second largest).
So, according to the experts, we seem to be warming on the top and cooling on the bottom, but we won’t know until the end of the year if 2010 will beat out 1998 for the warmest temperature on record.
How are the warming temperatures affecting the Earth? Let’s travel to some tropical locations and see what’s happening. And just in case you don’t believe NOAA’s statistics, experts at work in Africa have gathered some data that’s a lot older than NOAA’s.
WARMING IN LAYERS
Lake Tanganyika is the second oldest and the second-deepest lake in the world. Geologists from Brown University have recently discovered that the east African rift lake has experienced unprecedented warming during the last century, and its surface waters are now the warmest on record. This is important, because the warm surface waters likely will affect the fish that live in the lake; fish that millions of people in the region depend on for food.
The team took core samples from the bottom of the lake that showed a 1,500-year history of the lake’s surface temperature. The data showed the lake’s surface temperature which was 78.8 degrees F. is the warmest the lake has been for 1500 years. The data also show that Lake Tanganyika experienced its biggest temperature change in the 20th century.
Lake Tanganyika is bordered by Burundi, the Democratic Republic of Congo, Tanzania, and Zambia — four of the world’s poorest countries. An estimated 10 million people live near the lake and depend on it for drinking water and food. Up to 200,000 tons of sardines and other fish species are harvested annually from Lake Tanganyika, a haul that makes up a significant portion of local residents’ diets.
Lake Tanganyika, one of the richest freshwater ecosystems in the world, is divided into two levels. Most of the fish live in the upper 300 feet, including the valuable sardines. Below that, the lake holds less and less oxygen, and at certain depths, it’s anoxic: it has no oxygen at all.
The lake is highly stratified and wind-blown waves send nutrients from the depths toward the surface as food for algae, which supports the entire food web of the lake. But as Lake Tanganyika warms, there is less mixing of the two strata, meaning that fewer nutrients are funneled from the depths toward the surface. Surface warming also intensifies the difference in density between the two levels.
The researchers’ data show that during the last 1,500 years, intervals of prolonged warming and cooling are linked with low and high algal productivity, respectively, indicating a clear link between past temperature changes and biological productivity in the lake.
Climate change models show that central Africa will become even warmer meaning that stratification in Lake Tanganyika will increase and fish populations will fall. They’re already falling, something that has been attributed to overfishing, but the new research may be telling us that global warming is really the culprit.
Researchers drilled cores into Lake Tanganyika to document the lake’s surface temperature for the last 1,500 years. They found unprecedented warming in the 20th century. Brown geologist James Russell, kneeling at drill head, led this core sampling mission in 2004. (Credit: Kate Whittaker)
Let’s take another trip in the tropics to a place that more of us are familiar with. Let’s travel to Indonesia. So . . when you think of Indonesia, what do you think of? Well, personally I think of Bali since I’ve been there and in general, I picture a place that’s much like home. I certainly do NOT picture snow and ice, but as it turns out, I’d be wrong. But apparently not for much longer!
Yes indeed, there is a snow and ice covered ridge in Indonesia. The mountain is called Puncak Jaya and the ridge is 16,000 feet high. Puncak Jaya is also called Mt. Carstensz and it’s the highest mountain between the Andes and the Himalayas. It’s located in Papua New Guinea. The researchers are from Ohio State and they drilled three ice cores, two to bedrock, into the peak’s rapidly shrinking ice caps. Along with the ice cores, the team collected rainwater samples from locations ranging in elevation from sea level up to the site of the glacier. They hope the cores and accompanying data will provide a long-term record of the El Nino-Southern Oscillation (ENSO) phenomenon that dominates climate variability in the tropics.
Although with an average length of 100 feet, the three cores are relatively short compared to cores retrieved in other places, the researchers won’t know what history they contain until they are analyzed. A 130 foot core drilled in the year 2000 through ice fields on Mount Kilimanjaro in Africa yielded an 11,700-year history of climate.
The drill site turned out to be quite dangerous for a number of reasons. The area was riddled with crevasses meaning that the team had to wear crampons — pointed metal cleats on their boots — to maneuver on the ice. Daily rainstorms in the area, complete with lightning, increased the risks at the drill site.
The expedition was stalled almost before it began when the equipment delivered to the drill site had no ice core drills. While one of the corporate members of the drilling team attempted to make an ice core drill in their machine shop, a couple of the researchers flew to Jakarta and eventually found the lost equipment inside the shipper’s warehouse.
The next threat to the expedition was a little more serious. Four local tribes claim the ice fields as their own. They believe that the ice is their god’s skull, that the mountains are its arms and legs. The tribes feared that the scientists had come to drill into their god’s skull and steal their tribal memories. They also believe that they are a part of nature, and by extension a part of the ice, so if it disappears, a part of their souls will also be lost.
After the cores were drilled some of the tribal members broke into the freezer facility where the cores were stored, intent on destroying them. The researchers, fearing that something like this was brewing, had secretly transported the ice to another facility for safekeeping a few hours earlier.
Several days later, at a public forum the scientists addressed over 100 tribal members to explain the importance of the project to understanding local and global climate changes. After hours of discussion, the local people agreed to allow the ice cores to be returned to Ohio State for analysis.
The ice fields near Punkak Jaya are tiny. Together they total a little over half a square mile, roughly the same amount of ice that remains on the peak of Mount Kilimanjaro in Africa. If present warming trends continue, the snow and ice in both places will soon be gone.
Above, one of the drill camps perched precariously between crevasses in the ice field on Puncak Jaya. (Credit: Photo courtesy of Lonnie Thompson, Ohio State University.)
Welcome to The Deep science and technology column where we cover topics from the deep sea to deep space and beyond.
Well, the condition of the files tells me that an excursion into the wonderful world of animals is long overdue. Our first stop takes us to some very strange little microscopic creatures and we’ll also take a little side tour through the vagaries of the English language. Then it will be on to some less favored creatures.
Our first stop will be to visit the bdelloid rotifers. Ah, you’re thinking, any word that begins with the letters ‘b’ and ‘d’ together has to be the problem with the English language, right? Well, bdella is the Greek word for leech but even I was unaware that the Greeks stuck ‘b’ and ‘d’ together like that.
No, that’s not the English problem. In the article I examined about the rotifers, it confidently proclaimed “Bdelloid rotifers (pronounced DELL — oyd ROW-tiff-ers)”. Well, that takes care of the ‘b’ and the ‘d’ (goodbye B), but does it really help you correctly pronounce ‘rotifers’?
Well, no, since the word ‘row’ can be pronounced to rhyme with ‘go’ as in “Row, row, row your boat” but it can also be pronounced to rhyme with ‘cow’ as in “That was quite a row at the bar last night”. So which is it? In rotifer, the ‘ro’ is pronounced to rhyme with ‘go’. Don’t you just love English???
BORNE ON THE WIND
Not only is their name strange. Bdelloid rotifers are parthenogenic, which means that there’s only one sex (female) and the girls have done without sex for at least 30 million years. As if that weren’t enough to set them apart, biologists have recently discovered that they should have gone extinct long ago.
Because rotifers are completely asexual animals, they should have been killed off by parasites and pathogens. Asexual animals like rotifers reproduce by cloning and this makes for a fixed gene pool. Instead, bdelloid rotifers have proliferated into more than 450 species.
Many scientists believe that the function of sex itself is to shuffle genes around. They theorize that the fresh genetic combinations that sex provides allow sexual animals to fend off relentlessly evolving parasites and pathogens.
So, how have rotifers managed to escape their predators? They’re microscopic escape artists. When facing pathogens and predators, they dry up and blow away. Then, when they’re exposed to fresh water, they promptly come back to life.
In the current study, the researchers infected rotifer populations with deadly fungi and found that they all died within a few weeks. Then they dried out infected populations for varying lengths of time before rehydrating them. They discovered the fungi were far more sensitive to dehydration than the rotifers. The longer the infected populations remained dried out, the more successful they were at completely ridding themselves of fungi and eluding death.
In a different set of experiments, the researchers placed dried, fungus-infected rotifers in a wind chamber. They observed that the rotifers dispersed without the fungi and established parasite-free populations. After just seven days of blowing around, there were as many fungus-free rotifer populations as there were after three weeks of dehydration without wind. So, by drying and drifting passively on the wind — sometimes for hundreds of miles — bdelloids can continually establish new, uninfected populations.
One of the researchers said, “These animals are essentially playing an evolutionary game of hide and seek. They can drift on the wind to colonize parasite-free habitat patches where they reproduce rapidly and depart again before their enemies catch up. This effectively enables them to evade biotic enemies without sex, using mechanisms that no other known animals can duplicate.”
A spore-bearing fungal parasite emerges from the digested corpse of a bdelloid rotifer. New research reveals that bdelloids can escape fungal parasites through complete desiccation and dispersal by wind to uninfected habitats. (Credit: Image courtesy of Kent Loeffler, Kathie T. Hodge and Chris Wilson; copyright Chris Wilson)
Apparently they can drift for more than hundreds of miles because bdelloid rotifers are common in all of Guam’s freshwater rivers and lakes. They are indeed amazing animals.
And now we continue our animal trek with another amazing animal. And most of us will be VERY happy that this one isn’t with us any more! Maybe.
THE GIANT RAT OF . . . East Timor???
Archaeologists doing research in East Timor have unearthed the bones of the biggest rat that ever lived, with a body weight around thirteen pounds.
And that wasn’t all. The excavations yielded 13 species of rodents, 11 of which are new to science. Eight of the rats weighed more than two pounds.
It turns out that Eastern Indonesia is a hotbed of rodent evolution. Since rodents make up 40 percent of mammalian diversity worldwide and are key components of most forest and jungle ecosystems (they are usually dinner) protecting their biodiversity is just as important as protecting whales or koalas, even if they aren’t nearly as cute.
Carbon dating shows that the biggest rat that ever lived survived until around 1000 to 2000 years ago, along with most of the other Timorese rodents found during the excavation. Only one of the smaller species found is known to survive on Timor today.
Each of the islands of eastern Indonesia evolved it own unique collection of rats. Researchers have also found six new rat species in a cave on the island of Flores. Some of these might still be living on Flores but they have evaded detection by modern collectors and further surveys are urgently needed.
Timor has few native mammals, with bats and rodents making up the majority of species. Most of Timor is arid today, transformed from the lush rainforests of the past. Only 15 percent of Timor’s original forest cover remains.
But that 15 percent is deep and mainly unexplored. Dr. Ken Alpin, the prime investigator says, "During a recent field trip in East Timor, I found the remains of a freshly dead rat which we knew about only from cave deposits."
Until Dr Aplin finds a larger one, today’s biggest rats weigh around 2 kg and live in rainforests in the Philippines and New Guinea.
The skull of a black rat (right) compared with a fairly complete skull of one of Timor’s extinct giant rats (left). The giant rat shown here isn’t the biggest of the extinct rats, which was around 25 per cent bigger again. Credit: Ken Aplin, CSIRO)
So, rats aren’t your favorite animals, especially ones bigger than Agana sewer rats? So, we’ll move on to a story about an animal that may not be your favorite either, but has a lot more positive image. And you’ll like this story!
GOING ON STRIKE
So, you live in the land of the midnight Sun. North of the Arctic Circle where the Sun doesn’t set for months at a time. And . . . you are a honey bee. So, since your purpose in life is to gather that pollen to make that honey, and you’ve got to make enough to get you and the rest of the colony through the long Arctic night, you’re going to gather that pollen 24/7, right? Wrong!
According to some recent experiments by English biologists working in northern Finland, bees observe a strict working day, even in conditions of 24-hour sunlight. They tagged bees with a radio identifier, which was used to monitor their movements during the constant light of Arctic summer.
The researchers studied both native bees and a group of bee colonies they imported into the Arctic. Both species worked a day shift, with maximum activity around midday, and retired to their nests well before midnight. The scientists say that the bees must have some way of telling the time in the absence of day/night cues, suggesting that the insects may be sensitive to light intensity and quality or changes in temperature.
The researchers said, "Despite the light, temperatures do fall during the Arctic ‘night’, so it may be that the bees need to return to their nests in order to warm their brood. Also, it has been suggested that a period of sleep helps bees to remember information gained during the day’s foraging."
These bumblebees are tagged with rfid chips. (Credit: Stelzer et al., BMC Biology)
So, we’ve done rotifers and rats and bumblebees but there is a much bigger question here. Specifically, why ARE we all here? Why isn’t the world populated with Compys and Hadrosaurs and T. rex?
SURVIVING THE BIG ONE
I mean, picture a dinosaur. Although most of them were NOT the huge, menacing creatures, that usually spring to mind, they DID rule the Earth for nearly 200 million years. Yet all of them (well, maybe NOT the birds) were no match for a 6-mile wide meteor that struck modern-day Mexico 65 million years ago, incinerating everything in its path. This catastrophic impact spelled doom for the dinosaurs and many other species. Some animals, however, including many small mammals, managed to survive.
How did they do it?
Not only did they escape the impact, they were better at escaping the heat. There was a huge amount of heat released by the meteor strike that was the main cause of the K/T extinction."
Underground burrows and aquatic environments protected small mammals from the brief but drastic rise in temperature. In contrast, the larger dinosaurs would have been completely exposed, and vast numbers would have been instantly burned to death.
After several days of searing heat, the earth’s surface temperature returned to bearable levels, and the mammals emerged from their burrows to a barren wasteland. But the much smaller mammals had a different diet than the larger dinosaurs.
The large herbivorous dinosaurs died because most plant material had been destroyed. The endless night that followed the meteor strike meant that the plants didn’t come back very soon. (And most of them were the seeded plants because seeds survived better than spores.)
The mammals could eat insects and aquatic plants, which were relatively abundant after the meteor strike. And of course, since most small mammals even today are omnivores, there was certainly a lot of baked dinosaur available!
Depiction of the K/T meteor impact. (Credit: Image courtesy of Penn State)
Jim is, above all, a passionate eco-humanitarian who has developed his own science talk-radio show to inform The DEEP’s listeners about such newsy topics as global warming, shark-finning and reef protection as well as to explore earth’s many underwater and space mysteries.
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