Stories tagged impact crater
A dazzling fireball comes blazing in: Photo by Hiroyuki Iida of Toyama, Japan, courtesy NASA.Hundreds of Peruvian villagers have reportedly fallen ill from what they say are noxious gases coming from an impact crater left by something from space that slammed into the region.
A fiery object was seen falling to Earth last weekend over Carancas, a small town located in the Andes near in the Bolivian border, about 800 miles south of Lima.
People who visited the reported impact site say gases emitting from a large crater found there have caused them to suffer nausea, vomiting, eye irritations, and severe headaches. Livestock in the area have also become sick.
But not everyone believes the located “impact crater” has anything to do with the fiery object seen in the sky. Dr. Caroline Smith, a British museum meteorite expert, says it may just be mistaken for a crater.
"Increasingly we think that people witnessed a fireball, which are not uncommon, went off to investigate and found a lake of sedimentary deposit, which may be full of smelly, methane rich organic matter," she said.
An engineer from the Peruvian Nuclear Energy Institute reported no radiation has been detected at the site, and a team of scientists is on its way to the crater to investigate and gather further evidence. In the meantime, local authorities have been asked to warn people to stay away from the site.
Video from the site shows what appears to be a large crater 100-foot-wide by 20-foot-deep (another source states the crater is half this size). Marco Limache, a local official, reported that "boiling water started coming out of the crater, and particles of rock and cinders were found nearby."
If it proves to be a meteor crater, then it’s possible that sulfur or other elements in the extraterrestrial rock that caused the impact could have reacted with the ground water to produce the noxious gases.
Whatever it was - a fireball or a meteorite or possible space junk returning to Earth – it’s made a lot of local people nervous, and worried that the water is no longer safe to drink.
"This is the water we use for the animals, and for us, for everyone, and it looks like it is contaminated,” said one local villager.
"We don't know what is going on at the moment, that is what we are worried about,” he added.
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Ejecta from Sudbury Impact found in Minnesota: Photo by Mark Jirsa, Minnesota Geological SurveyNew evidence of an ancient meteorite impact in Ontario, Canada, has been found nearly 500 miles away in Minnesota.
Mark Jirsa of the Minnesota Geological Survey said the recent Ham Lake forest fire that raged over 118 square miles near the Gunflint Trail in northern Minnesota had caused the annual meeting of the Institute of Lake Superior Geology (ILSG) Institute of Lake Superior Geology (ILSG) to cancel one of its planned field trip into the region last May.
But because he’s a geologist, Jirsa wasn’t going to let a little conflagration ruin his chances to examine outcrop, so he sojourned into the area on his own to look for possible alternate sites.
Map showing Sudbury Impact and Gunflint Trail locations: Diagram by Mark RyanWhile examining some of the Gunflint Iron Formation in an area he hadn’t visited before, he discovered an odd jumble of rounded black rock overlying the formation, which he now thinks may be partially composed of ejected material from the Sudbury Impact which took place 1,875 million years ago in Ontario.
“It’s fairly dark rock,” Jirsa explained. “They look like concrete, but in this concrete you would throw pieces of rock of all sizes and shapes and in all possible orientations.”
It’s thought that the Sudbury Impact site was created when an extraterrestrial object such as a comet or asteroid between 6 and 12 miles in diameter slammed into the Earth near the present-day town of Sudbury, Ontario, just north of Lake Huron. The effects of the impact were widespread, releasing as much energy as several billion atomic bombs, blasting out more than 6500 cubic miles of debris that blanketed nearly one million square miles with impact ejecta. The crater it left was over 160 miles in diameter, the second largest on Earth.
Some of this ejecta fell into the shallow ocean that covered northern Minnesota at the time. But soon after, shock wave-induced tsunamis would have tore across the area with such force the seabed would have been severely disrupted.
“When the meteorite hit, it’s very likely that the seas went out and then the seas came back in with a vengeance,” Jirsa said.
Consequently, the ejecta and the seabed material would become mixed into a jumbled mess of sediment that would later harden into rock. This is what Jirsa thinks he’s come across along the Gunflint Trail.
Studies of lunar impact craters show that an ejecta blanket five times larger than the crater is usually created from a typical impact. Products of impact range from angular fragments of preexisting rocks and partially melted, recrystallized, or glassy fragments. But unlike the airless Moon, Earth’s atmosphere would have additional effects on the ejecta, producing such things as spherules that condense from vapor in the ejecta cloud (like hail stones forming in rain clouds).
Jirsa showed his discovery to an ILSG colleague named William Addison, who with Gregory Brumpton had first identified Sudbury Impact ejecta 15 years ago near Thunder Bay, Ontario. Addison immediately recognized that the samples exhibited typical textures of material formed in an impact. Interestingly, Addison and Brumpton are both high school earth science teachers, and not professional geologists.
William Cannon of the United States Geological Survey joined the search and has located and documented exposures of ejecta blanket in or near five iron ranges in the Lake Superior region. And Jirsa’s Gunflint Trail discovery, 500 miles from the impact’s “ground zero”, adds another iron formation to the list.
Stromatolite fossils along Gunflint Trail: Photo by Mark Jirsa, Minnesota Geological SurveyIron deposits the same age as the Gunflint Iron Formation (about 2 billion years old) occur world-wide, and are thought to be result of high levels of oxygen present in the atmosphere, due to photosynthesis by cyanobacteria, Earth’s earliest preserved life form. Fossils of these ancient creatures called stromatolites are exposed in the upper layers of the Gunflint Iron Formation in the same area where Jirsa found the ejecta blanket evidence.
Interestingly, the deposition of iron-forming sediments declined right around the same time as the Sudbury Impact (1.875 billion years ago), and Cannon wonders if there may be a connection between the two events. Could the impact have caused the cyanobacteria to go extinct, thereby ending the favorable conditions for iron deposit formation?
“There’s a lot of work that needs to be done in the field to see what this deposit tells us that other sites don’t,” Jirsa said. “That’s the critical thing. This is a different geological setting; it’s a little farther away from the impact, the rocks are altered differently. It may reveal some secrets about the impact that other discoveries haven’t yet. That’s what we’re hoping.”
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Story in Minneapolis Star Tribune
Another story source
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More on impact craters
More on cyanobacteria
Sudbury Impact layer in Michigan
Fallen Trees at Tunguska site: 1927 Kulik expeditionA team of scientists may have finally found a possible impact crater from the Tunguska event that blasted above Siberia nearly a century ago.
Map showing Tunguska event location: Image source: Public DomainOn June 30, 1908, some sort of extraterrestrial object, such as a comet or an asteroid (at least according to the consensus), exploded in Earth’s atmosphere above the Tunguska River with such force that it flattened more than 2000 square miles of forest. But until now, no viable impact site had ever been found.
This whole Tunguska thing is cloaked in so much mystery and mythology, that agents Muldar and Scully could do a whole X-Files episode about it (in fact, they did). Well, the truth may be out there, but there’s a whole lot of it that remains unknown.
What’s is known is that something big exploded over the Tunguska river region in 1908. The place, unfortunately, is so out-in-the-middle-of-nowhere; it wasn’t scientifically investigated until more than two decades later when mineralogist Leonid Kulik led the first official expedition into the region in 1927. Kulik had initially come upon the site six years earlier when he doing a survey for the Soviet Academy of Sciences. Local eyewitness accounts convinced him that the explosion had been caused by an enormous meteorite impact, and he persuaded the Soviet government to fund the expedition in hopes of salvaging meteoric iron for Soviet industry. But to his disappointment, no possible impact crater was ever located (except in one bare location that later proved to be just a bog). What the expedition did find was a huge area of forest flattened out in a butterfly pattern. Oddly, the only trees still standing were located at ground zero, but those had been stripped bare of all their leaves and bark.
Kulik didn’t find any chunks of iron either, although later expeditions did find microscopic traces of nickel and iron in the soil.
But now, a University of Bologna team of scientists claims that Lake Cheko, which is located just 5 miles north-northwest of the explosion’s epicenter, shows some interesting features that could be interpreted as resulting from some sort of impact, perhaps from a small chunk of the disintegrating space rock – if that’s what it was. The team’s research appears in the online journal Terra Nova.
But other scientists aren’t jumping on the bandwagon just yet. For one thing the lake exhibits almost none of the usual telltale physical markings of an impact crater, other than being uniquely funnel-shaped unlike other neighboring lakes. And even then, its shape is more elliptical than circular. Cheko’s rim is not raised and lacks any sign of upturned ejecta. The scientists have found no shocked terrestrial rock in or around the lake, and to date no meteoric material either. And even if some is found, skeptics say it could have washed into the lake from the surrounding landscape. Also, trees older than a hundred years old are still standing near the lake. If Cheko were an impact crater, the force of the collision would have knocked them all down. It’s true that the lake doesn’t appear on any map prior to 1929, but the region is extremely remote, and there is some folklore evidence of its existence before then.
Other scientists speculate that the source of the event wasn’t from outer space at all, but rather was caused by geophysical forces, such as a cataclysmic gas blow out from deep inside the Earth. It just so happens that the Tunguska event epicenter sets at the intersection of a number of tectonic faults, and atop the ancient crater of a paleovolcano. Kimberlite pipes are also found in the area, an indication of magma reservoirs deep beneath the surface. And evidently there was a lot of earthquake activity in the Tunguska epicenter region back in 1908.
Andrei Ol'khovatov, a former Soviet scientist who is now -in his own words- “an independent researcher/expert” on everything Tunguska, has an entire website addressing this and other possibilities about the event. He has participated in a number of International Tunguska conferences, and I found his site very interesting to peruse.
So, whatever the Tunguska event was, whether it was a comet or asteroid, a UFO, an errant radio transmission, or the real cause of global warning - it exploded about 3-6 miles above the ground, knocked down a whole lot of lumber, scared the dickens out of the locals, and illuminated the sky so brightly it could be seen in London, a third of the way around the globe!
The Italian team plans to return to Lake Cheko in 2008 to perform further tests, including drilling into the core of the lake to examine an anomaly detected some 10 meters below the lake bottom. It could be a meteorite fragment or maybe just some compacted mud. I guess we’ll have to wait and see.
MORE INFO
More on the Tunguska event
The Tunguska event in fiction
BBC website story
Lake Cheko story on Sky& Telescope website
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