7 Ways the Earth Changes in the Blink of an Eye
1/ Meteor impact
Many meteors headed for Earth burn up in the planet's atmosphere. Those big enough to make it through leave quite an impression on the landscape.
The Earth's wind, water and vegetation will eventually erase most craters. With few exceptions, even the largest craters are eventually destroyed by the processes of plate tectonics.
The Barringer Crater, also known as Meteor Crater, is a 0.8-mile- (1,300-meter-) diameter, 570-foot- (174-m-) deep hole in the flat-lying desert sandstones that lies 18.6 miles (30 kilometers) west of Winslow, Ariz.
2/ Rapid megafloods
Some of the most spectacular canyons on Earth (and Mars) were probably formed in the geologic blink of an eye, suggests a recent study that found clues to their formation deep in the heart of Texas.
As anyone living in Comal County, Texas can attest, they can form even faster. Lake Canyon Gorge, a 23-feet- deep (7 meters) canyon was carved in just three days by a flood in 2002. The flood scoured a swath of greenery in this Texas town, leaving sand-colored bedrock rubble in its wake.
A single catastrophic flood capable of cutting into bedrock is extremely rare, but the Comal flood gave scientists a front-row ticket to an event similar to those from the planet's distant past, geologists said.
Rapid megafloods may have formed other canyons in the distant past as glacial ice dams released trapped water. Large floods may be responsible for the formation of some Martian canyons as well, said geologists.
Canyons Form Quickly, Recent Gusher Suggests
| Waterfall created during the flood that rapidly formed Lake Canyon Gorge. Credit: Richard Sears |
Some of the most spectacular canyons on Earth and Mars were probably formed in the geologic blink of an eye, suggests a new study that found clues to their formation deep in the heart of Texas.
Lake Canyon Gorge, a 23-feet- (7-meter-) deep canyon in Comal County, Texas, was carved in just three days by a flood in 2002. The flood scoured a swath of greenery, leaving sand-colored bedrock rubble in its wake.
"It was just a little v-shaped ditched before, but all that material was busted out during that event," said engineer Tom Hornseth of Comal County, Texas.
Data gathered at this gorge will help researchers reconstruct the formation of ancient canyons.
A single catastrophic flood capable of cutting into bedrock is extremely rare, but the Comal flood gave scientists a front-row ticket to an event similar to those from the planet's distant past.
Researchers climbed into the canyon, measured the rate and volume of the flood and took aerial photographs to document the rapid erosion. Their study is detailed in the June 20 early online edition of the journal Nature Geoscience.
Gorges are typically formed along pre-existing river channels. TheGrand Canyon was formed as the Colorado River slowly wore down the bedrock. That probably took millions of years though, said geologist and study co-author Michael Lamb of Caltech in Pasadena, Calif.
Rapid gorge carving is a baffling example of how incising bedrock doesn't take millions of years. At Lake Canyon Gorge, a single burst of water carried away heavy rocks, a process known to geologists as plucking. These sedimentary rocks were already broken down into pieces weighing a couple of tons, but exactly how this happens is not well understood, Lamb told OurAmazingPlanet.
Rapid megafloods may have formed canyons in the distant past as glacial ice dams released trapped water. Large floods may be responsible for the formation of some Martian canyons as well, the study suggests.
3/ Avalanches
When mountaintop glaciers collapse, they can trigger an avalanche of ice and debris down the mountain. Such was the case for Mt. Kazbeck in Southern Russia when the Kolka Glacier collapsed on Sept. 20, 2002.
In the above image, the dark grey streak shows the gorge that was overrun by ice, rock, water and other debris from the avalanche. The avalanche plowed down the Genaldon River Valley at speeds up to 112 mph (180 kph) and buried parts of a village with a layer of ice and rock 427 feet (130 meters) thick.
Avalanches, along with other deadly natural disasters such as heat waves and floods, could become more common in mountainous regions thanks to climate change, according to a recent study. In the Alps, where temperatures have increased twice as much as the global average temperature since the late 19th century and are predicted to rise by an average of 0.54 to 0.9 degrees Fahrenheit (0.3 to 0.5 Celsius) per decade in the next century, these threats are a real concern.
4/ Landslides
Landslides can wipe away villages in the blink of an eye even when volcanoes aren't involved. Heavy rains triggered landslides on the slopes of Mount Elgon in Uganda, on March 1, 2010.
Landslides are common in the region, but these recent landslides are much larger than previous ones. The landslides buried three villages, leaving 83 dead and more than 300 missing as of March 8, reported the United Nations Office for the Coordination of Humanitarian Affairs. The Ugandan government has also stated that deforestation may have played a role in the landslides.
5/Volcano collapse
Massive volcanic eruptions unleash ash and pumice into the sky and can be heard thousands of miles away and even seen from space . But volcanoes can change the landscape in the blink of an eye in a way other than blowing off their tops by triggering huge landslides.
Thousands of years ago, a large collapse of the edifice of the Soufriere Hills volcano on the island of Montserrat in the Lesser Antilles sent landslides into the ocean. Some of these landslides involved nearly 1.2 cubic miles (5 cubic kilometers) of material that travelled underwaterfor miles.
Volcanic dome collapses occur when dome-shaped lava mounds on top of a volcano break apart due to a gas pressure build-up. Soufriere Hills' eruptions have produced some of the largest volcanic dome collapses ever recorded.
Amazing Images: Volcanoes from Space
Klyuchevskaya Volcano
The snow-covered Klyuchevskaya Volcano on Russia's Kamchatka Peninsula part of the highly volcanically and seismically active Pacific "Ring of Fire." Klyuchevskaya the largest active volcano in the Northern Hemisphere is seen here erupting in March 2010.
The volcanic plume, low-lying clouds and snow are all white in the image taken by NASA's Earth Observing-1 satellite, while a lava flow on the shadowed (northern) flank of the mountain is nearly black.
The 15,863-foot (4,835-meter) high volcano has erupted nearly continuously since it first formed about 6,000 years ago.
The volcanic plume, low-lying clouds and snow are all white in the image taken by NASA's Earth Observing-1 satellite, while a lava flow on the shadowed (northern) flank of the mountain is nearly black.
The 15,863-foot (4,835-meter) high volcano has erupted nearly continuously since it first formed about 6,000 years ago.
Anak Krakatau
Anak Krakatau ("Son of Krakatau") is the volcanic island that formed in the caldera of Krakatau (also written Krakatoa), which erupted catastrophically in 1883. It sits in the Sunda Strait between the Indonesian islands of Java and Sumatra.
That massive eruption spewed huge amounts of ash and pumice into the sky and could be heard thousands of miles away. Tsunamis spawned by the eruption inundated nearby parts of Indonesia, killing some 36,000 people one of the most devastating eruptions in history.
Anak Krakatau arose less than 50 years after the 1883 eruption and has seen frequent rumblings and outbursts since then.
That massive eruption spewed huge amounts of ash and pumice into the sky and could be heard thousands of miles away. Tsunamis spawned by the eruption inundated nearby parts of Indonesia, killing some 36,000 people one of the most devastating eruptions in history.
Anak Krakatau arose less than 50 years after the 1883 eruption and has seen frequent rumblings and outbursts since then.
Eyjafjallajökull Volcano
Eyjafjallajökull began pumping ash into the atmosphere on March 20, 2010. As the plume was blown across Europe, it severely hampered air travel while it also produced spectacularly red sunsets.
How long Eyjafjallajökull will continue to erupt for is up in the air, though in the past a single eruption has lasted for years. The inter-connected magma chambers of many of Iceland's volcanoes give them a unique dynamic, and Eyjafjallajökull connects to another nearby volcano, Katla, which has a history of erupting not long after its neighbor.
The volcanoes of Iceland are what created the island about 70 million years ago. The small European nation is situated on the Mid-Atlantic Rise, a seam in the Earth's surface under the North Atlantic Ocean where the Eurasian and North American plates slide apart. Magma upwells along the rise and spreads out to create new crust. Iceland is thought to sit on a pocket of magma that created the island and continues to fuel its many volcanoes today.
How long Eyjafjallajökull will continue to erupt for is up in the air, though in the past a single eruption has lasted for years. The inter-connected magma chambers of many of Iceland's volcanoes give them a unique dynamic, and Eyjafjallajökull connects to another nearby volcano, Katla, which has a history of erupting not long after its neighbor.
The volcanoes of Iceland are what created the island about 70 million years ago. The small European nation is situated on the Mid-Atlantic Rise, a seam in the Earth's surface under the North Atlantic Ocean where the Eurasian and North American plates slide apart. Magma upwells along the rise and spreads out to create new crust. Iceland is thought to sit on a pocket of magma that created the island and continues to fuel its many volcanoes today.
Mount Etna
Here, Sicily's Mount Etna Italy's most active volcano sits mostly quiet in March 2010, though thin brown and white plumes rise above the Central Crater (also known as Bocca Nuova) and the Northeast Crater.
This shield volcano rises 10,925 feet (3,330 meters) high and has one of the longest documented records of eruption, dating back to 1500 B.C.
Etna's last eruption ended in June 2009, according to the Istituto Nazionale di Geofisica e Vulcanologia Sezione di Catania.
This shield volcano rises 10,925 feet (3,330 meters) high and has one of the longest documented records of eruption, dating back to 1500 B.C.
Etna's last eruption ended in June 2009, according to the Istituto Nazionale di Geofisica e Vulcanologia Sezione di Catania.
Kilauea's Halema'uma'u Crater
A lava-filled pit set inside Kilauea's Halema'uma'u Crater emitted a plume of steam, ash and sulfur dioxide earlier this year as seen in this image from NASA's Earth-Observing-1 satellite.
Halema'uma'u Crater is itself a crater in the larger Kilauea Caldera the smaller pit opened up in its southwestern wall on March 19, 2008. Volcanic emissions have continued almost uninterrupted since, punctuated occasionally by violent explosions of ash and fragments of rock torn from the crater walls.
On September 5, 2008, scientists at the Hawaii Volcano Observatory discovered a lava lake inside the pit.
Halema'uma'u Crater is itself a crater in the larger Kilauea Caldera the smaller pit opened up in its southwestern wall on March 19, 2008. Volcanic emissions have continued almost uninterrupted since, punctuated occasionally by violent explosions of ash and fragments of rock torn from the crater walls.
On September 5, 2008, scientists at the Hawaii Volcano Observatory discovered a lava lake inside the pit.
Mount St. Helens
Mount St. Helens blew in a cataclysmic eruption on May 18, 1980. That eruption blew ash high into the atmosphere, where it was picked up and carried for thousands of miles.
The eruption killed 57 people and devastated the local landscape, which is still recovering more than 30 years later. During the eruption, the north flank of the volcano slid away in the largest landslide in recorded history.
The Mount St. Helens eruption taught scientists much about looking for warning signs of eruptions at it and other volcanoes. The volcano rumbled back to life in 2004, though the eruptions from that episode were far milder than the 1980 disaster.
The eruption killed 57 people and devastated the local landscape, which is still recovering more than 30 years later. During the eruption, the north flank of the volcano slid away in the largest landslide in recorded history.
The Mount St. Helens eruption taught scientists much about looking for warning signs of eruptions at it and other volcanoes. The volcano rumbled back to life in 2004, though the eruptions from that episode were far milder than the 1980 disaster.
Jebel at Tair
ebel at Tair, a small volcanic island in the Red Sea, erupted in late September 2007. A plume of smoke from the volcano was caught in this Nov. 8, 2007 image taken by NASA's EO-1 satellite.
The dark stains on the volcano's slopes are evidence of earlier lava flows.
This stratovolcano sits midway between Yemen and Eritrea and is made up of alternating layers of hardened lava, solidified ash and rocks ejected from eruptions.
The dark stains on the volcano's slopes are evidence of earlier lava flows.
This stratovolcano sits midway between Yemen and Eritrea and is made up of alternating layers of hardened lava, solidified ash and rocks ejected from eruptions.
Submarine Eruption in Tonga Islands
This submarine eruption, captured by NASA's Aqua satellite, occurred in the Tonga Islands of the South Pacific in mid-March 2009.
The area around the eruption appears bright blue-green, likely resulting from ash and other volcanic debris suspended in the water. The brilliant white patch may result from vapor released by the volcano.
Northwest of the eruption, a ribbon of brown is likely a pumice raft pumice is highly porous and floats on water. When a lot of pumice if thrown from an erupting volcano it can bunch together into a "raft." Just such a raft occurred after an August 2006 eruption.
The area around the eruption appears bright blue-green, likely resulting from ash and other volcanic debris suspended in the water. The brilliant white patch may result from vapor released by the volcano.
Northwest of the eruption, a ribbon of brown is likely a pumice raft pumice is highly porous and floats on water. When a lot of pumice if thrown from an erupting volcano it can bunch together into a "raft." Just such a raft occurred after an August 2006 eruption.
Ol Doinyo Lengai
Ol Doinyo Langai in Tanzania is the only volcano in the world that erupts what is called natrocarbonatite lava, which is rich in calcium, sodium and potassium, but low in silica (silicon dioxide).
>The lava of Ol Doinyo Lengai is extremely cool (932 to 1,112 degrees Fahrenheit, or 500 to 600 degrees Celsius, compared to 2,120 F, or 1,160 C, for typical basaltic lava) and relatively fluid.
The volcano switches from periods where it erupts liquid lava that pools into lava lakes to explosive periods where it builds large ash cones. In the image, acquired with NASA's Earth-Observing-1 satellite, dark areas on the crater floor are recent lava flows (days to weeks old), while the beige and white regions are older lava that has reacted with rain and moisture in the atmosphere.
>The lava of Ol Doinyo Lengai is extremely cool (932 to 1,112 degrees Fahrenheit, or 500 to 600 degrees Celsius, compared to 2,120 F, or 1,160 C, for typical basaltic lava) and relatively fluid.
The volcano switches from periods where it erupts liquid lava that pools into lava lakes to explosive periods where it builds large ash cones. In the image, acquired with NASA's Earth-Observing-1 satellite, dark areas on the crater floor are recent lava flows (days to weeks old), while the beige and white regions are older lava that has reacted with rain and moisture in the atmosphere.
Manam Volcano
Manam volcano is one of Papua New Guinea's volcanoes. In this June 28, 2009, image, a faint plume rises from the volcano.
Manam is a stratovolcano that measures 6 miles (10 kilometers) across. Frequent historical eruptions, typically of fairly mild character, have been recorded at Manam since 1616, according to the Smithsonian's Global Volcanism Program.
Eruptions from the volcano have caused casualties, including 13 deaths from a pyroclastic flow in December 1996, and four deaths from a mudflow in March 2007. Large eruptions in late 2004 forced the evacuation of the entire island
Manam is a stratovolcano that measures 6 miles (10 kilometers) across. Frequent historical eruptions, typically of fairly mild character, have been recorded at Manam since 1616, according to the Smithsonian's Global Volcanism Program.
Eruptions from the volcano have caused casualties, including 13 deaths from a pyroclastic flow in December 1996, and four deaths from a mudflow in March 2007. Large eruptions in late 2004 forced the evacuation of the entire island
Turrialba Volcano
A translucent plume of smoke rises from Turrialba Volcano, located in central Costa Rica.
The 10,960-foot (3,340-meter) summit of the volcano appears grey and brown in this image taken by NASA's Earth-Observing-1 satellite because it is barren. Five major explosive eruptions have occurred at Turrialba during the past 3,500 years.
While much of the forest and fields around the volcano appear a verdant green, some vegetation shows signs of damage. Since 2007, frequent acid rain showers caused by activity at the volcano have killed or damaged much of the vegetation to the southwest of the summit, leaving the area brown and orange.
The 10,960-foot (3,340-meter) summit of the volcano appears grey and brown in this image taken by NASA's Earth-Observing-1 satellite because it is barren. Five major explosive eruptions have occurred at Turrialba during the past 3,500 years.
While much of the forest and fields around the volcano appear a verdant green, some vegetation shows signs of damage. Since 2007, frequent acid rain showers caused by activity at the volcano have killed or damaged much of the vegetation to the southwest of the summit, leaving the area brown and orange.
Minchinmávida and Chaitén Volcanoes
The Chaitén and Minchinmávida Volcanoes lie in the Andes Mountains, along the western coast of South America, which is host to numerous volcanoes. The volcanoes were created by, and are still fueled by, the magma generated as the Nazca tectonic plate subducts under the South American plate.
The two volcanoes shown in this photo taken by an astronaut aboard the International Space Station lie near the southern boundary of the NazcaSouth America subduction zone in southern Chile.
Charles Darwin observed an eruption of Minchinmávida during his Galapagos Islands voyage in 1834. The volcano's last recorded eruption took place the following year.
Chaitén has erupted more recently - it roared to life unexpectedly on May 2, 2008, generating dense ash plumes and forcing the evacuation of the nearby town of Chaitén. Volcanic activity continued at Chaitén in early 2009; several days before this astronaut photograph was taken, a new lava dome partially collapsed and generated a pyroclastic flow (a scalding avalanche of gas, ash, and rock debris).
The two volcanoes shown in this photo taken by an astronaut aboard the International Space Station lie near the southern boundary of the NazcaSouth America subduction zone in southern Chile.
Charles Darwin observed an eruption of Minchinmávida during his Galapagos Islands voyage in 1834. The volcano's last recorded eruption took place the following year.
Chaitén has erupted more recently - it roared to life unexpectedly on May 2, 2008, generating dense ash plumes and forcing the evacuation of the nearby town of Chaitén. Volcanic activity continued at Chaitén in early 2009; several days before this astronaut photograph was taken, a new lava dome partially collapsed and generated a pyroclastic flow (a scalding avalanche of gas, ash, and rock debris).
6/Ice conveyor belt
Glaciers huge rivers of ice formed when snow and ice accumulate over hundreds and thousands of years act like a big conveyor belt that pushes ice into the sea. These icy rivers move slowly over time, some eventually dumping ice chunks into the sea, a process known as calving a leading source of additional water for the world's oceans.
Some kinds of glaciers, however, calve as often as once an hour. These kinds of glaciers are called "grounded," meaning they rest on the ocean floor; others float on top of the ocean waters as they run into the sea. Scientists recently observed Alaska's Columbia Glacier undergoing a transition from grounded to floating, which dramatically slowed its
Tracking a Retreating Glacier
Columbia Glacier
Scientists set up camp where the Columbia Glacier meets the ocean in this photo from August 2009. The scientists' orange tents are seen on the cliff in the lower left-hand corner of the image.
Glacier Camp
Only accessible by helicopter, three to five scientists will spend up to a month camped out on the wet terrain surrounding the glacier. They deploy instruments to measure the glaciers, take photographs and make observations in the field. The instruments do not transmit their data back to the lab, so twice a year scientists trek to Columbia to retrieve it.
Iceberg are born
Scientists captured a dramatic submarine iceberg calving at the grounded end of the Columbia Glacier on June 17, 2005. The height of the ice cliff is roughly 230 feet (70 meters)
Glaciologist O'Neel of the USGS is pictured here checking up on the seismometer that measured the activity of the Columbia Glacier in May 2009.
"Think of a calving event kind of like a little earthquake," O'Neel told OurAmazingPlanet. "Seismometers tell us when and how long it took to break off, and also gives us ideas about how it was created."
"Think of a calving event kind of like a little earthquake," O'Neel told OurAmazingPlanet. "Seismometers tell us when and how long it took to break off, and also gives us ideas about how it was created."
Conveyor Belt of Ice
Tad Pfeffer is seen photographing the Columbia Glacier from the western boundary in June 2005. The scientists do more than just take pretty pictures. Try also make quantitative measurements with their images. Pictures taken with this camera help scientists calculate how fast the ice is flowing and also measure the glacier's geometry.
Time-Lapse Photography
Adam LeWinter is servicing one of the time-lapse cameras at Columbia Glacier. Time-lapse images provide one of the primary sources of data used in this study.
"We use them to identify times when large calving events occur and then look at the seismic data during those periods to study the fracture process," O'Neel said.
In 2004, the time-lapse cameras took four to six pictures per day. Today they snap photographs every 20 minutes.
"We use them to identify times when large calving events occur and then look at the seismic data during those periods to study the fracture process," O'Neel said.
In 2004, the time-lapse cameras took four to six pictures per day. Today they snap photographs every 20 minutes.
7/A new coast
Earthquakes not only rattle the Earth, but they radically change the landscape. The Chilean earthquake that struck on Feb. 27 changed the country's landscape by raising the ground by more than 8 feet (2.5 meters) near the coast and sinking land farther inward, a recent study found.
The massive quake caused marine platforms to rise out of the ocean, thereby shifting the coastline in some places 1,640 feet (500 m) closer to the ocean. [See images of Chile's raised coast.]
Chile's Raised Coast
Caleta Yane
The Chilean earthquake that struck on Feb. 27 changed the country's landscape by raising the ground near the coast and sinking land farther inward, a new study finds. Here on the Arauco Peninsula, the uplift of a marine terrace displaced the coastline about 980 feet (300 meters) seaward.
New coast
Uplift of the ground is seen at the beach of Lebu. Uplift in this zone was about 71 inches (180 centimeters), which produced the uplift of a great marine platform.
Punta Lavapié
An uplifted marine platform was found at Punta Lavapié (the northernmost tip of the Arauco Peninsula). Here, the coastline before the earthquake was just at the foot of the cliff.
This photograph shows several species of dead algae and mollusks that lived in the coastal waters.
The white coating on the rocks is from the dead algae. Researchers used the white fringe to measure how far the land had risen after the earthquake. These normally pink algae, common in Chilean coastal waters, are bleached and dried out by sunshine. The algae died and turned white when the land was pushed above the water's surface.
Santa Maria Island
At the southern end of Santa Maria Island, several marine platforms uplifted more than 5 feet (1.5 m), leaving some species far from their living zone. Sea lions, seen here, are now more than 16 feet (5 m) from sea-level.
Arauco Peninsula
The magnitude 8.8 earthquake also caused massive landslides, as seen in this image of the coastal slope of the Arauco Peninsula.
Raised marine platform
A marine platform rose from the waters at Caleta Yani, on the Arauco Peninsula. Here, uplift was about 51 inches (130 centimeters), and killed almost all the mollusks and algae that live in the waters near the shore.
White fringe
The uplifted marine platform in Caleta Yani was covered in dead white algae after the earthquake
Dichato, Chile
Studying how the earthquake moved the land is more than an academic curiosity. Chile is situated atop a hotspot for earthquake activity. Learning how this magnitude 8.8 quake moved the land will tell scientists more about what causes large earthquakes.
In this image, uplift is seen in the south part of the city of Dichato, home to 3,000 people.
Accessing the damage
The city of Dichato was one of the hardest hit by a tsunami that reached 33 feet (10 m) high, and washed more than 0.6 miles (1 kilometer) landward. An estimated 90 percent of the town was destroyed.
The new study that measured the land changes in this area is just one of many studies currently investigating the Chilean earthquake, which geophysicist Michael Bevis of Ohio State University said "will probably turn out to be one of the most important earthquakes ever in terms of scientific impact."
Huge Chilean Earthquake Raised Country's Coast
Uplift of the ground is seen at the beach of Lebu. Uplift in this zone was about 71 inches (180 centimeters), which produced the uplift of a great marine platform.
The Chilean earthquake that struck on Feb. 27 changed the country’s landscape by raising the ground by more than 8 feet near the coast and sinking land farther inward, a new study finds.
Chile is situated atop a hotspot for earthquake activity, so learning how this magnitude 8.8 quake moved the land will tell scientists more about what causes large earthquakes.
The massive earthquake struck south-central Chile and was the fifth largest temblor ever recorded by modern seismology. A nearby part of Chile gave birth to the largest earthquake ever recorded — a magnitude 9.5 earthquake that struck in May 1960 and killed 5,700 people. Since 1973, 13 quakes of magnitude 7.0 or greater have hit the coastal country, according to the U.S. Geological Survey (USGS).
Huge Chilean Earthquake Raised Country's Coast
The Chilean earthquake that struck on Feb. 27 changed the country’s landscape by raising the ground by more than 8 feet near the coast and sinking land farther inward, a new study finds.
Chile is situated atop a hotspot for earthquake activity, so learning how this magnitude 8.8 quake moved the land will tell scientists more about what causes large earthquakes.
The massive earthquake struck south-central Chile and was the fifth largest temblor ever recorded by modern seismology. A nearby part of Chile gave birth to the largest earthquake ever recorded — a magnitude 9.5 earthquake that struck in May 1960 and killed 5,700 people. Since 1973, 13 quakes of magnitude 7.0 or greater have hit the coastal country, according to the U.S. Geological Survey (USGS).
Scientists have now confirmed for the first time that the 2010 quake ruptured a long fault along the coast of Chile, and found that it raised land to a higher elevation in the south and sunk the Earth's surface in the North, according to the study.
To the scientists patrolling the coast, the change is obvious.
"You can just see the sea shells and sea weed hanging in the air, about head high," said Michael Bevis, a geophysicist at Ohio State University who was not involved with the study but has conducted his own studies of the Chilean coast. "You see all this stuff that belongs underwater is now up in the rocks."
Researchers found a white fringe formed by a kind of dead algae that is common along the Chilean coast. These normally pink algae are bleached by sunshine, and gave researchers a direct way to measure the grounds' uplift. [See images of Chile's raised coast]
Using the algae as a marker, the research team, led by Marcelo Farias at the University of Chile, found that the largest uplift was roughly 8.2 feet (2.5 meters) at the Arauco Peninsula. The uplift also shifted the coastline in some places 1,640 feet (500 m) toward the ocean.
Measuring how much the land sank was somewhat trickier. The researchers gauged sinking by measuring how high the water had risen on vegetation and manmade constructions like bridges. A 3.3 foot (1 m) drop in land was measured in some parts, but the study acknowledges some uncertainly about the subsidence level because of the difficulty in knowing the water levels before the quake hit, and exactly how these water levels changed after the quake.
Despite this uncertainty, the research team arrived at the site of the quake so quickly — taking measurements within a month of the rupture — that they were able to measure the sudden jump of the land that happens after an earthquake, Bevis said. This is important because the land continues to shift over time. Separating out the various ground movements is one step toward painting a picture of how the land moves during massive quakes.
The new study is just one of many studies currently investigating theChilean earthquake, which Bevis said "will probably turn out to be one of the most important earthquakes ever in terms of scientific impact."
"We've instrumented the crap out of the fifth biggest quake ever," Bevis told OurAmazingPlanet. "When we put this data together we're going to figure out what happened during and after the earthquake with an impressive level of detail."
Other movements around South America caused by the earthquake include:
Chile is situated atop a hotspot for earthquake activity, so learning how this magnitude 8.8 quake moved the land will tell scientists more about what causes large earthquakes.
The massive earthquake struck south-central Chile and was the fifth largest temblor ever recorded by modern seismology. A nearby part of Chile gave birth to the largest earthquake ever recorded — a magnitude 9.5 earthquake that struck in May 1960 and killed 5,700 people. Since 1973, 13 quakes of magnitude 7.0 or greater have hit the coastal country, according to the U.S. Geological Survey (USGS).
Scientists have now confirmed for the first time that the 2010 quake ruptured a long fault along the coast of Chile, and found that it raised land to a higher elevation in the south and sunk the Earth's surface in the North, according to the study.
To the scientists patrolling the coast, the change is obvious.
"You can just see the sea shells and sea weed hanging in the air, about head high," said Michael Bevis, a geophysicist at Ohio State University who was not involved with the study but has conducted his own studies of the Chilean coast. "You see all this stuff that belongs underwater is now up in the rocks."
Researchers found a white fringe formed by a kind of dead algae that is common along the Chilean coast. These normally pink algae are bleached by sunshine, and gave researchers a direct way to measure the grounds' uplift. [See images of Chile's raised coast]
Using the algae as a marker, the research team, led by Marcelo Farias at the University of Chile, found that the largest uplift was roughly 8.2 feet (2.5 meters) at the Arauco Peninsula. The uplift also shifted the coastline in some places 1,640 feet (500 m) toward the ocean.
Measuring how much the land sank was somewhat trickier. The researchers gauged sinking by measuring how high the water had risen on vegetation and manmade constructions like bridges. A 3.3 foot (1 m) drop in land was measured in some parts, but the study acknowledges some uncertainly about the subsidence level because of the difficulty in knowing the water levels before the quake hit, and exactly how these water levels changed after the quake.
Despite this uncertainty, the research team arrived at the site of the quake so quickly — taking measurements within a month of the rupture — that they were able to measure the sudden jump of the land that happens after an earthquake, Bevis said. This is important because the land continues to shift over time. Separating out the various ground movements is one step toward painting a picture of how the land moves during massive quakes.
The new study is just one of many studies currently investigating theChilean earthquake, which Bevis said "will probably turn out to be one of the most important earthquakes ever in terms of scientific impact."
"We've instrumented the crap out of the fifth biggest quake ever," Bevis told OurAmazingPlanet. "When we put this data together we're going to figure out what happened during and after the earthquake with an impressive level of detail."
Other movements around South America caused by the earthquake include:
- The Chilean city of Concepción moved at least 10 feet (3 meters) to the west.
- Buenos Aires, the capital of Argentina and across the continent from the quake's epicenter, moved about 1 inch (2.5 centimeters) to the west.
- Chile's capital, Santiago, moved about 11 inches (28 cm) to the west-southwest.
- The cities of Valparaiso and Mendoza, Argentina, northeast of Concepción, also moved significantly.
- http://www.livescience.com
Chile Earthquake: Is Mother Nature Out of Control?
Chile is on a hotspot of sorts for earthquake activity. And so the 8.8-magnitude temblor that shook the capital region overnight was not a surprise, historically speaking. Nor was it outside the realm of normal, scientists say, even though it comes on the heels of other major earthquakes.
One scientist, however, says that relative to a time period in the past, the Earth has been more active over the past 15 years or so.
The Chilean earthquake, and the tsunami it spawned, originated on a hot spot known as a subduction zone, where one plate of Earth's crust dives under another. It's part of the very active "Ring of Fire," a zone of major crustal plate clashes that surround the Pacific Ocean.
"This particular subduction zone has produced very damaging earthquakes throughout its history," said Randy Baldwin, a geophysicist with the U.S. Geological Survey (USGS).
The world's largest quake ever recorded, magnitude 9.5, occurred along the same fault zone in May 1960.
Even so, magnitude-8 earthquakes occur globally, on average, just once a year. Since magnitudes are given on a logarithmic scale, an 8.8-magnitude is much more intense than a magnitude 8, and so this event would be even rarer, said J. Ramón Arrowsmith, a geologist at Arizona State University.
Is Earth shaking more?
The Ryukyu Islands of Japan were hit with a 7.0-magnitude quake just last night. News of this, the Haiti quake and now Chile make it seem Earth is becoming ever more active. But in the grand scheme of things, geologists say this is just Mother Nature as usual.
"From our human perspective with our relatively short and incomplete memories and better and better communications around the world, we hear about more earthquakes and it seems like they are more frequent," Arrowsmith said. "But this is probably not any indication of a global change in earthquake rate of significance."
Coupled with better communication, as the human population skyrockets and we move into more hazardous regions, we're going to hear more about the events that do occur, Arrowsmith added.
However, "relative to the 20-year period from the mid 1970's to the mid 1990's, the Earth has been more active over the past 15 or so years," said Stephen S. Gao, a geophysicist at Missouri University of Science & Technology. "We still do not know the reason for this yet. Could simply be the natural temporal variation of the stress field in the earth's lithosphere." (The lithosphere is the outer solid part of the Earth.)
And while the Chilean earthquake wasn't directly related to Japan's 7.0-magnitude temblor, the two have some factors in common.
For one, any seismic waves that did make their way from Japan to the Chilean coast could play a slight role in ground-shaking.
"It is too far away for any direct triggering, and those distances also make the seismic waves as they would pass by from the Haiti or Japan events pretty small because of attenuation," Arrowsmith told LiveScience. (Attenuation is the decrease in energy with distance.) "Nevertheless, if the Chilean fault surface were close to failure, those small waves could push it even closer."
In addition, both regions reside within the Ring of Fire, which is a zone surrounding the Pacific Ocean where the Pacific tectonic plate and other plates dive beneath other slabs of Earth. About 90 percent of the world's earthquakes occur along this arc. (The next most seismic region, where just 5 to 6 percent of temblors occur, is the Alpide belt, which extends from the Mediterranean region eastward.)
Colliding plates
The Chilean earthquake occurred at the boundary between the Nazca and South American tectonic plates. These rocky slabs are converging at a rate of 3 inches (80 mm) per year, according to the USGS. This huge jolt happened as the Nazca plate moved down and landward below the South American plate. This is called a subduction zone when one plate subducts beneath another.
(Over time, the overriding South American Plate gets lifted up, creating the towering Andes Mountains.)
The plate movement explains why coastal Chile has such a history of powerful earthquakes. Since 1973, 13 temblors of magnitude 7.0 or greater have occurred there, according to the USGS.
In fact, today’s earthquake originated about 140 miles (230 km) north of the source region of the magnitude 9.5 earthquake of May, 1960, considered the largest instrumentally recorded earthquake in the world.
The 1960 earthquake killed 1,655 people in southern Chile, unleashing atsunami that crossed the Pacific and killed 61 people in Hawaii, Japan, and the Philippines.
In November 1922, a magnitude-8.5 earthquake occurred about 540 miles (870 km) to the north of the Feb. 27 earthquake, triggering a local tsunami that inundated the Chile coast and crossed the Pacific to Hawaii.
Because the recent one was such a huge earthquake, the shaking would likely have caused just as much damage had a similar-sized event occurred elsewhere, said Baldwin, the USGS scientist.
"If [the quake] were in Los Angeles you'd probably have massive destruction too," Baldwin said in a telephone interview.
Earthquakes Rock in Synchrony, Study Suggests
Some powerful earthquakes can set off other big quakes on faults many miles away, with just a tiny nudge, because the faults have become synchronized over millennia, a new study suggests.
Scientists already knew that big earthquakes can trigger other big quakes by transferring stress along a single fault, but they did not know about the synchrony. Here's how it works:
When a fault ruptures in a large earthquake, the movement releases stresses that may have built up over hundreds or thousands of years and transfers some of that released stress to nearby faults. In order for that tiny added stress to trigger a large earthquake on a nearby fault, that fault had to already be very near its breaking point, said study author and seismologist Christopher Scholz of Columbia University in New York.
For the two faults to have been simultaneously near their breaking points requires them to be synchronized in their seismic cycles.
"All of a sudden bang, bang, bang, a whole bunch of faults break at the same time," Scholz said.
That changes how future quake risk will be assessed. Seismologists had assumed that when a fault ruptures, the risk for another big quake generally goes down.
"Now that we know that some faults may act in consort, our basic concept of seismic hazard changes," Scholz said. "When a large earthquake happens, it may no longer mean that the immediate future risk is lower, but higher."
The researchers analyzed earthquake patterns as far back as 15,000 years and identified strings of related earthquakes. Their work explains how closely spaced faults that rupture every few thousand years might align themselves to rupture almost simultaneously.
Southern California's Mojave Desert, the mountains of central Nevada and the south of Iceland each may have synchronized, or "phase locked," faults in their respective immediate vicinities, according to the study, detailed in the June issue of the Bulletin of the Seismological Society of America.
When faults lie relatively close, between 6.2 and 31 miles (10 and 50 km) apart, and are moving at comparable speeds, they may break successively over time because their cycles may eventually fall in sync, Scholz said. This is similar to how two pendulums hanging off the same rod will become synchronized as their motions are communicated along the rod.
In the Mojave Desert, the Camp Rock fault, off the San Andreas fault, ruptured in 1992, causing a magnitude 7.3 quake in the town of Landers, killing one child. Seven years later, the Pisgah fault, 15 miles (24 km) away, broke, causing a magnitude 7.1 quake at Hector Mine, inside the Twentynine Palms Marine Corps Base.
Scholz said his hypothesis of synchronized faults could make it easier to assess some earthquake hazards by showing that faults moving at similar speeds, and within roughly 31 miles (50 km) of each other, may break at similar times, while faults moving at greatly different speeds, and located relatively far apart, will not.
However, seismologists have yet to come up with a reliable method for predicting imminent earthquakes; the best they can do so far is to identify dangerous areas, and roughly estimate how often quakes of certain sizes may strike.
Scientists already knew that big earthquakes can trigger other big quakes by transferring stress along a single fault, but they did not know about the synchrony. Here's how it works:
When a fault ruptures in a large earthquake, the movement releases stresses that may have built up over hundreds or thousands of years and transfers some of that released stress to nearby faults. In order for that tiny added stress to trigger a large earthquake on a nearby fault, that fault had to already be very near its breaking point, said study author and seismologist Christopher Scholz of Columbia University in New York.
For the two faults to have been simultaneously near their breaking points requires them to be synchronized in their seismic cycles.
"All of a sudden bang, bang, bang, a whole bunch of faults break at the same time," Scholz said.
That changes how future quake risk will be assessed. Seismologists had assumed that when a fault ruptures, the risk for another big quake generally goes down.
"Now that we know that some faults may act in consort, our basic concept of seismic hazard changes," Scholz said. "When a large earthquake happens, it may no longer mean that the immediate future risk is lower, but higher."
The researchers analyzed earthquake patterns as far back as 15,000 years and identified strings of related earthquakes. Their work explains how closely spaced faults that rupture every few thousand years might align themselves to rupture almost simultaneously.
Southern California's Mojave Desert, the mountains of central Nevada and the south of Iceland each may have synchronized, or "phase locked," faults in their respective immediate vicinities, according to the study, detailed in the June issue of the Bulletin of the Seismological Society of America.
When faults lie relatively close, between 6.2 and 31 miles (10 and 50 km) apart, and are moving at comparable speeds, they may break successively over time because their cycles may eventually fall in sync, Scholz said. This is similar to how two pendulums hanging off the same rod will become synchronized as their motions are communicated along the rod.
In the Mojave Desert, the Camp Rock fault, off the San Andreas fault, ruptured in 1992, causing a magnitude 7.3 quake in the town of Landers, killing one child. Seven years later, the Pisgah fault, 15 miles (24 km) away, broke, causing a magnitude 7.1 quake at Hector Mine, inside the Twentynine Palms Marine Corps Base.
Scholz said his hypothesis of synchronized faults could make it easier to assess some earthquake hazards by showing that faults moving at similar speeds, and within roughly 31 miles (50 km) of each other, may break at similar times, while faults moving at greatly different speeds, and located relatively far apart, will not.
However, seismologists have yet to come up with a reliable method for predicting imminent earthquakes; the best they can do so far is to identify dangerous areas, and roughly estimate how often quakes of certain sizes may strike.
Big Quakes Trigger Global Shaking
The giant earthquake that unleashed the Indian Ocean tsunamis in 2004 — killing more than 225,000 people in one of the deadliest natural disasters in history — might also have triggered other quakes around the world, new findings reveal.
The earthquake that ravaged China last week may also have set off other quakes around the globe, but that data has not been analyzed yet. But the new research shows that major earthquakes may routinely set off smaller jolts, even on the opposite side of the planet and in areas not prone to quakes.
Earthquakes rank among the most destructive events on the planet. The 2004 Indian Ocean quake was magnitude 9.3 , unleashing some 1.3 billion tons of TNT's worth of energy, said researcher Aaron Velasco, a seismologist at the University of Texas at El Paso. That is the equivalent of nearly 100,000 Hiroshima bombs, making it the second largest quake ever recorded with instruments.
And the effects of earthquakes can be felt far and wide. The earthquake that just hit China, a magnitude 7.9, shook buildings in Shanghai at least 1,000 miles away from its epicenter in Sichuan.
New thinking
Until recently, scientists did not think major earthquakes set off smaller tremors at distant locations. Then, in 1992, they found that California’s magnitude-7.3 Landers earthquake set off small jolts as far away as Yellowstone National Park.
While the 1992 findings suggested earthquakes could trigger smaller quakes nearby, how far major earthquakes could reach was a mystery. To investigate further, scientists analyzed 15 earthquakes of magnitude 7 or greater that occurred since 1990. These included the 2004 Indian Ocean earthquake, as well as the 1999 Izmit earthquake in Turkey that killed at least 15,000 and left a half-million homeless.
By studying rumbles in the ground five hours before and five hours after these earthquakes — data gathered from more than 500 research stations worldwide — the researchers found that 12 of these large earthquakes generated surface waves that set off quakes around the planet. For instance, the 2004 Indian Ocean earthquake triggered small earthquakes as far away as Alaska, California and Ecuador.
There are normally about 600 small seismic events around the Earth every five minutes, and after major quakes, the researchers found that on average, more than twice the normal number of small earthquakes occurred. Some quakes triggered far more rumbles than this average — after the 2004 Indian Ocean earthquake, there were roughly 2,400 more small quakes detected than normal.
Specifically, the researchers found that surface waves from major quakes can often trigger magnitude 4 or smaller earthquakes.
More to learn
There are two kinds of surface waves earthquakes generate — Love waves, which move in a shearing fashion, and Rayleigh waves, which have a rolling motion.
Much about earthquakes is still mysterious
, however, and it remains unknown how exactly these surface waves trigger smaller quakes at distant locations.
"The passage of the waves may change the water flow in a fault, possibly increasing the number of conduits that water can flow through which could cause the fault to slip," said researcher Kris Pankow, a seismologist at the University of Utah. Surface waves might also increase the strain on a fault, or loosen a fault so that it prematurely breaks or slides, she adds.
When the Sichuan quake happened, "we analyzed data from the continental U.S. over 300 stations," Velasco told LiveScience. Surprisingly, they found no significant increase in rumbles due to the Chinese quake. Of course, other stations around the world might have detected quakes, data that have not been analyzed yet, he added. Alternatively, perhaps the Sichuan quake may not have sent much out in terms of surface waves.
One question now is "do large quakes trigger other large quakes?" Velasco said. "Probably not. But we really need to better understand how stresses from these earthquakes are doing the triggering, the dynamics of what's happening."
Velasco, Pankow and their colleagues Tom Parsons and Stephen Hernandez detailed their findings online May 25 in the journal Nature Geoscience. The study was funded by the United States Geological Survey and the National Science Foundation.
The earthquake that ravaged China last week may also have set off other quakes around the globe, but that data has not been analyzed yet. But the new research shows that major earthquakes may routinely set off smaller jolts, even on the opposite side of the planet and in areas not prone to quakes.
Earthquakes rank among the most destructive events on the planet. The 2004 Indian Ocean quake was magnitude 9.3 , unleashing some 1.3 billion tons of TNT's worth of energy, said researcher Aaron Velasco, a seismologist at the University of Texas at El Paso. That is the equivalent of nearly 100,000 Hiroshima bombs, making it the second largest quake ever recorded with instruments.
And the effects of earthquakes can be felt far and wide. The earthquake that just hit China, a magnitude 7.9, shook buildings in Shanghai at least 1,000 miles away from its epicenter in Sichuan.
New thinking
Until recently, scientists did not think major earthquakes set off smaller tremors at distant locations. Then, in 1992, they found that California’s magnitude-7.3 Landers earthquake set off small jolts as far away as Yellowstone National Park.
While the 1992 findings suggested earthquakes could trigger smaller quakes nearby, how far major earthquakes could reach was a mystery. To investigate further, scientists analyzed 15 earthquakes of magnitude 7 or greater that occurred since 1990. These included the 2004 Indian Ocean earthquake, as well as the 1999 Izmit earthquake in Turkey that killed at least 15,000 and left a half-million homeless.
By studying rumbles in the ground five hours before and five hours after these earthquakes — data gathered from more than 500 research stations worldwide — the researchers found that 12 of these large earthquakes generated surface waves that set off quakes around the planet. For instance, the 2004 Indian Ocean earthquake triggered small earthquakes as far away as Alaska, California and Ecuador.
There are normally about 600 small seismic events around the Earth every five minutes, and after major quakes, the researchers found that on average, more than twice the normal number of small earthquakes occurred. Some quakes triggered far more rumbles than this average — after the 2004 Indian Ocean earthquake, there were roughly 2,400 more small quakes detected than normal.
Specifically, the researchers found that surface waves from major quakes can often trigger magnitude 4 or smaller earthquakes.
More to learn
There are two kinds of surface waves earthquakes generate — Love waves, which move in a shearing fashion, and Rayleigh waves, which have a rolling motion.
Much about earthquakes is still mysterious
, however, and it remains unknown how exactly these surface waves trigger smaller quakes at distant locations.
"The passage of the waves may change the water flow in a fault, possibly increasing the number of conduits that water can flow through which could cause the fault to slip," said researcher Kris Pankow, a seismologist at the University of Utah. Surface waves might also increase the strain on a fault, or loosen a fault so that it prematurely breaks or slides, she adds.
When the Sichuan quake happened, "we analyzed data from the continental U.S. over 300 stations," Velasco told LiveScience. Surprisingly, they found no significant increase in rumbles due to the Chinese quake. Of course, other stations around the world might have detected quakes, data that have not been analyzed yet, he added. Alternatively, perhaps the Sichuan quake may not have sent much out in terms of surface waves.
One question now is "do large quakes trigger other large quakes?" Velasco said. "Probably not. But we really need to better understand how stresses from these earthquakes are doing the triggering, the dynamics of what's happening."
Velasco, Pankow and their colleagues Tom Parsons and Stephen Hernandez detailed their findings online May 25 in the journal Nature Geoscience. The study was funded by the United States Geological Survey and the National Science Foundation.
