Satellite Imagery Shows How Tornadoes Slashed Across Alabama, Mississippi

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Some extraordinary satellite and radar imagery shows how the deadly tornado supercell slashed through Alabama and Mississippi last week, as in the image above, leaving a gash of exposed ground and destruction that is visible from space. The latest reports indicate fatalities from the outbreak now exceed 342 people, and according to the Washington Post, this is the most people killed by tornadoes in a two-day period since April 5-6, 1936 when 454 people died. The image was taken by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite on April 28. See more imagery below.

Part of the path of a 12-mile swath of destruction in Alabama from an EF4 tornado on April 27. Click to see the entire swath taken by a NOAA satellite. Credit: NOAA

The National Weather Service said an EF4, with winds around 175 miles per hour, created a 12-mile-long track of destruction. This tornado caused more than 20 deaths.

Radar sequence of tornado supercell thunderstorms that tracked from western Mississippi into southwest North Carolina. Credit: NCAR, Brian Tang.

This image is pretty amazing: it is a radar montage of the supercell showing some of the 150 tornadoes that were reported on April 27 and 28, 2011. This cell traveled about 450 miles and lasted over 8 hours.

This animation from the NASA Earth Observatory team starts on April 26 and runs through the morning of April 28. It shows a relatively stable mass of cold air—visible as a swirl of more-or-less continuous clouds—rotates in the north along the top of the image, and meanwhile, moist air pushes north and west from the Atlantic Ocean and Gulf of Mexico. The two air masses collide and generate severe weather, but the bad weather also was amplified by the jet stream on April 27, which helped generate the lines of intense thunderstorms and tornadoes.

Sources: NASA Earth Observatory, Washington Post, NOAA

Japan Quake May Have Shortened Earth Days, Moved Axis

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The terribly destructive magnitude 9.0 earthquake which struck Japan on March 11, may have had another effect – Shortening the length of each Earth day and shifting its axis. Did you notice any change ?

Well according to NASA, the changes are so small that you won’t notice the difference.

Based on initial calculations conducted by Richard Gross, a research scientist at NASA’s Jet Propulsion Laboratory, the earthquake should have caused Earth to rotate just slightly faster, shortening the length of the day by about 1.8 microseconds (a microsecond is one millionth of a second), according to a statement released by NASA.

A reader posted this link to before and after photos

Gross used complex modeling and estimates of fault slippage to perform a preliminary theoretical calculation of how the earth’s rotation may have been affected.

Calculations by Gross also indicate that the position of Earth’s figure axis could have shifted by about 17 centimeters (6.5 inches), towards 133 degrees east longitude. The figure axis is the axis about which Earth’s mass is balanced.
Earth’s figure axis is therefore different and offset from the north-south axis by about 10 meters.

“This shift in Earth’s figure axis will cause Earth to wobble a bit differently as it rotates, but it will not cause a shift of Earth’s axis in space-only external forces such as the gravitational attraction of the sun, moon and planets can do that,” according to the NASA statement.

The estimates for both the shortening in the Earth’s rotation and shift in the figure axis are preliminary and will very likely change as more data is collected and the calculations are refined.

The March 11 earthquake was the fifth largest since 1900. So far, over 4000 people are confirmed dead and the overall death total may exceed 10,000.

Several heavily damaged nuclear reactors at the Fukushima plant are in danger of meltdown as hero workers inside put their lives on the line to avoid a catastrophic failure and try to prevent the spread of lethal radiation.

This view of Earth comes from NASA's Moderate Resolution Imaging Spectroradiometer aboard the Terra satellite

Previously, Gross had calculated the affects of the magnitude 8.8 Chilean quake in 2010 and found them to be slightly smaller compared to the Japanese quake. He calculated a shortening in the length of day of about 1.26 microseconds and shifting of Earth’s figure axis of about 8 centimeters (3 inches). These affects are dependent on the magnitude of the quake, exactly where it is located as well as how the particulars of how the fault slips.

In fact, Earth’s rotation is changing all the time as a result of continual changes in atmospheric winds and oceanic currents and these effects are about 550 times larger than the Japanese earthquake.

“Over the course of a year, the length of the day increases and decreases by about a millisecond,” says Gross. Indeed, the effects of earthquakes on changing rotation are so tiny that they are smaller than the margin of error in the measurements themselves.

By comparison, measurements of the figure axis are much more reliable and meaningful. Changes to the figure axis can be accurately measured to within about 5 centimeters. This means that the estimated 17 centimeter shift from the Japanese quake may be real after accounting for the effects of the atmospheric winds and ocean currents. Further research is needed as more data are collected and analyzed.

“These changes in Earth’s rotation are perfectly natural and happen all the time. People shouldn’t worry about them,” said Gross.

Source: NASA Press Release:

Satellite Photos Before and After of Japan’s Earthquake, Tsunami

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Photos from the GeoEye satellite imaging company from before and after the March 11 earthquake and tsunami in Japan show sobering views from above of the disaster. Above is the town of Sendai, Japan after the quake, below is how it looked before catastrophe struck.

Arahama, Japan before the disaster. Satellite image courtesy of GeoEye.

See more below.

The Sendai Airport after the disaster. Satellite image courtesy of GeoEye.
The Sendai Airport in August of 2010. Satellite image courtesy of GeoEye.
Yuriage, Japan on March 12, 2011. Satellite image courtesy of GeoEye.
Yuriage, Japan on April 4, 2010. Satellite image courtesy of GeoEye.
Sendai, Japan on March 12, 2011. Satellite image courtesy of GeoEye.
Sendai, Japan on April 4, 2010. Satellite image courtesy of GeoEye.
Ishinomaki, Japan on March 12, 2011. Satellite image courtesy of GeoEye.
Ishinomaki, Japan on April 4, 2010. Satellite image courtesy of GeoEye.

Below is an images from the MODIS Rapid Response System, which is producing twice-daily images of Japan in response to the disaster.

The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite took the right image on Mar. 13, 2011, while the MODIS sensor on NASA’s Terra satellite took the left image on Feb 26, 2011. NASA images courtesy the MODIS Rapid Response Team at NASA GSFC.

These two images, from the MODIS instrument on NASA’s Aqua satellite from Mar. 13, 2011 on the right, and the the MODIS sensor on NASA’s Terra satellite from Feb. 26, 2011 on the left before the earthquake and tsunami. Both images were made with infrared and visible light to highlight the presence of water on the ground. Plant-covered land is bright green, bare earth is tan-pink, and snow is blue. The city of Sendai is brown.

At this level of detail, the flooding along the coastline is the most obvious sign of the destructive earthquake and tsunami that struck Japan on March 11. A bright orange-red spot near the city of Sendai is the thermal signature from a fire, also likely caused by the earthquake. The photo-like true-color version of the image shows a plume of black smoke extending east over the ocean.

The German Aerospace Center (Deutsches Zentrum fur Luft- und Raumfahrt; DLR) is responding through its Center for Satellite Based Crisis Information (Zentrum fur Satellitengestutzte Kriseninformation; ZKI), based at its site in Oberpfaffenhofen, and provided the image below.

Japan's Coastline Before and After the Tsunami These images show the effects of the tsunami on Japan's coastline. The image on the left was taken on Sept. 5, 2010; the image on the right was taken on March 12, 2011, one day after an earthquake and resulting tsunami struck the island nation. Image Credit: German Aerospace Center (DLR)/Rapid Eye

Sources: GeoEye, New York Times, NASA, Space Daily

The Science Behind a Tsunami

Model projections of wave heights from the Japan quake on Friday. Image from NOAA. Click image for higher resolution.

The massive magnitude 8.9 earthquake that struck off the east coast Japan’s main island on March 11, 2011 set in motion a fierce tsunami that may have claimed thousands of lives, and sent tsunami warnings all across the Pacific basin, thousands of kilometers away from the quake’s epicenter. How do earthquakes trigger such enormous tsunami events, and how can scientists predict where these massive waves might travel? Universe Today talked with Anne Sheehan, who is a professor of geological sciences at University of Colorado at Boulder, and is also affiliated with the Cooperative Institute for Research in Environmental Sciences, as well as getting input from David Admiraal, an associate professor of Engineering at the University of Nebraska Lincoln.

Universe Today: How does an earthquake trigger a tsunami?
Continue reading “The Science Behind a Tsunami”

Just to be Clear: The Moon Did Not Cause the Earthquake in Japan

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We’re getting a lot of visitors to our site today, many searching for information about earthquakes, tsunamis, and the ‘SuperMoon’ phenomenon. Just to be clear, the Moon did not cause the earthquake in Japan. Several scientists have posted articles online today clarifying the topic, and all of them, in no uncertain terms, agree that the the upcoming perigee of the Moon — where it is closer than usual in its orbit to Earth — had nothing to do with the earthquake and ensuing tsunami. Tammy discussed this yesterday, but as we often do, we’ll also point you in the direction of an article by astronomer Phil Plait about this topic, and another by Ben Goldacre, who completely debunks an article that appeared in the Daily Mail about the possibility of a connection between the two events.

In addition, Dr. Jim Garvin, chief scientist at NASA’s Goddard Space Flight Center, has provided some answers to questions about the ‘supermoon’ phenomenon, below:

Question: What is the definition of a supermoon and why is it called that?

Garvin: ‘Supermoon’ is a situation when the moon is slightly closer to Earth in its orbit than on average, and this effect is most noticeable when it occurs at the same time as a full moon. So, the moon may seem bigger although the difference in its distance from Earth is only a few percent at such times.

It is called a supermoon because this is a very noticeable alignment that at first glance would seem to have an effect. The ‘super’ in supermoon is really just the appearance of being closer, but unless we were measuring the Earth-Moon distance by laser rangefinders (as we do to track the LRO [Lunar Reconnaissance Orbiter] spacecraft in low lunar orbit and to watch the Earth-Moon distance over years), there is really no difference. The supermoon really attests to the wonderful new wealth of data NASA’s LRO mission has returned for the Moon, making several key science questions about our nearest neighbor all the more important.

Question: Are there any adverse effects on Earth because of the close proximity of the moon?

Garvin: The effects on Earth from a supermoon are minor, and according to the most detailed studies by terrestrial seismologists and volcanologists, the combination of the moon being at its closest to Earth in its orbit, and being in its ‘full moon’ configuration (relative to the Earth and sun), should not affect the internal energy balance of the Earth since there are lunar tides every day. The Earth has stored a tremendous amount of internal energy within its thin outer shell or crust, and the small differences in the tidal forces exerted by the moon (and sun) are not enough to fundamentally overcome the much larger forces within the planet due to convection (and other aspects of the internal energy balance that drives plate tectonics). Nonetheless, these supermoon times remind us of the effect of our ‘Africa-sized’ nearest neighbor on our lives, affecting ocean tides and contributing to many cultural aspects of our lives (as a visible aspect of how our planet is part of the solar system and space).

Massive 8.9 Earthquake Hits Japan; Tsunamis Predicted for Pacific Basin

Seismology

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An 8.9-magnitude earthquake struck off the coast of northern Japan on March 11, one of the strongest to ever hit Japan. The massive quake has triggered tsunamis not only in Japan, but around the Pacific Basin. Walls of water and debris have inundated coastal areas of Japan, and tsunami warnings were issued for at least 20 countries and numerous Pacific islands, including coastal Russia, the western coast of Canada and the US, the Marcus Islands, Taiwan, Guam and the Hawaiian Islands, where a full coastal evactuation has been taking place throughout early Friday morning. Strong aftershocks, as strong as 6.5-magnitude continue to shake the region, (the latest U.S. Geological Survey map, above, shows 95 recent quakes in the area) and at least one nuclear power plant in Japan may be encountering problems. Images coming from Japan show widespread damage from both the quakes and the tsunamis.

The USGS reported that the epicenter of the earthquake was 373 kilometers (231 miles) northeast of Tokyo and 130 km (80 miles) east of Sendai, Honshu. Police reports from Sendai say that so 200-300 bodies have been recovered, but the total death toll will likely be much, much higher. Reports say this is the 6th largest earthquake ever monitored, and the largest in Japan in over 140 years.

Tokyo did not suffer much damage, but in northern Japan, many areas were devastated. Compounding the damage was a wall of water that rushed inland of the island nation, leveling houses and washing away boats, cars and other debris. Click here to see some shocking images from the New York Times.

Reports says Japan is evacuating thousands of people from nearby a nuclear power plant, but the current condition of the reactor core is unknown at this time. Four reactors are located near the Earthquake area. The reactors were shut down, and no leaks have been found so far, but the cooling system for the reactors may not be working correctly.

Reports via Twitter say the roof may have collapsed at JAXA Tsukuba Space Center.

Tsunami waves have now begun to wash ashore in the Hawaiian Islands. The first waves are not necessarily the strongest; waves are predicted to be 2-3 meters (6-8 ft.) in Hawaii. Tsunamis are very hard to predict, and the USGS says wave heights can vary widely.

Get the latest on the tsunami predictions from NOAA’s Pacific Tsunami Warning Center.

See this Google Map, overlaid with NOAA-predicted tsunami times.

Callan Bentley at the AGU Blogosphere has a good overview of earthquake and tsunami dynamics.

Predicted tusnami map from the March 11 earthquake. Credit: CNN

Most Intense Storm in History Cuts Across the US — As Seen from Space

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Yowza! – Here’s a satellite image of a storm of record-breaking proportions. On October 26, 2010, the strongest storm ever recorded in the Midwest spawned 24 tornadoes, 282 reports of damaging winds, violent thunderstorms, and torrential rains. The mega-storm reached peak intensity late yesterday afternoon over Minnesota, resulting in the lowest barometric pressure readings ever recorded in the continental United States (except for from hurricanes and nor’easters affecting the Atlantic seaboard.) The storm continues today (Oct. 27) with more tornado watches posted for Mississippi, Alabama, and Georgia, a blizzard warning for North Dakota, high wind warnings for most of the upper Midwest, and near-hurricane force winds on Lake Superior.

Read more about this super-storm on Weather Underground, but see below for what extremely low air pressure means.

Air pressure is one of the most important factors which determines what the weather is like. A mass of low pressure is an area of air that is rising. As it rises, it expands and cools. Cooler air cannot hold as much water as warmer air, so as the air rises the water will condense and form clouds. This is why an area of low pressure will often be accompanied by clouds and rain — which is what occurred on October 26 — lots of clouds and lots of rain and even snow.

But winds were even a bigger factor in this superstorm. Our atmosphere really doesn’t like big differences in air pressure, so where areas of low pressure meet up with areas of high pressure, winds blow in an attempt to combat the differences in the air pressure. The larger the difference in pressure the stronger the winds will blow. So, the extreme low pressure readings yesterday meant the winds were really howling — and they were. In my neighborhood in Illinois, we had a fairly study flagpole get bent from the winds. But that was nothing compared to the hurricane-like winds other places experienced: for example, Grand Marais, Minnesota — near the Great Lakes and near the area of the lowest air pressure readings — had sustained winds of 43 mph gusting to 59 mph, lasting for over 7 hours. Today, that region is still getting pummeled by winds and snow.

You can see the link to Weather Underground above to see what other weather extremes were experienced during this storm.

Latest Satellite Images of Eyjafjallajokull, the Volcano that Keeps on Giving

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Iceland’s Eyjafjallajökull Volcano continues to spew out a thick plume of ash. Seen here on May 11, 2010, the ash was streaming almost directly south, visibly extending at least 860 kilometers (530 miles) from Eyjafjallajökull. According to the NASA’s Earth Observatory website and the London Volcanic Ash Advisory Center, the ash reached altitudes of 14,000 to 17,000 feet (4,300 to 5,200 meters). CNN reported that some Spanish and Moroccan airports were closed at the time. On May 10th, the Icelandic Met Office reported continuous ash fall south of the volcano, with as depths reaching 2-3 millimeters (roughly 0.1 inches). “Presently there are no indications that the eruption is about to end,” the Met Office said yesterday.

Astronomer Snaevarr Gudmundsson from Iceland who shared his amazing close-up images of the volcano a few weeks ago, sent an update on how Iceland is coping with continued eruption.

“By now ash has covered all surface snow and ice so the mountains looks quite different from the photographs what I mailed to you,” he said. “The eruption is affecting people in a small village southeast of Eyjafjallajokull, named Vik. There it is stopping normal life of people. They are leaving their homes and elementary school is forced to shut down, only because of the fine grained ash. But the people are not in a threat of anything serious like pyroclastic flow or poisoned gases.”

Gudmundsson said he would be venturing out for the next few days to try and take more images of the volcano, and will send us another update soon.

Here is another satellite image, of the Iceland volcano taken by Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite on May 10, 2010.

The Eyajafjallajokull volcano on May 10, 2010. NASA image courtesy Jeff Schmaltz, MODIS Rapid Response Team at NASA GSFC.

Source: NASA Earth Observatory

Spectacular Footage, Satellite Images of Eyjafjallajokull Volcano in Iceland

A volcano under a glacier in Iceland erupted Wednesday, melting ice, shooting smoke and steam into the air and forcing hundreds of people to leave their homes. The resulting ash plume has also halted air traffic over much of Europe. Scientists said the eruption under the ice cap was 10 to 20 times more powerful than an eruption from the that happened from the Eyjafjallajokullin Volcano late last month. “This is a very much more violent eruption because it’s interacting with ice and water,” said Andy Russell, an expert in glacial flooding at the University of Newcastle in northern England, in an article on the CBC website. The dramatic footage in the video here was released today, April 15, and satellite images, below, show how far the ash plume has traveled.

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The iceland volcano sent a plume of ash and steam across the North Atlantic prompting airspace closures in the United Kingdom, Ireland, France, and Scandinavia, which then had a ripple effect, disrupting flights to and from other countries as well. Authorities could not say how long the airspace closure would last, and the ash’s spread threatened to force closures of additional airspace over the coming days.

NASA's EO-1 Satellite took this image on April 1, 2010. NASA image by Robert Simmon, using ALI data from the EO-1 team

This natural-color satellite image shows the area of the eruption on April 1, when a new vent opened up. The image was acquired by the Advanced Land Imager (ALI) aboard NASA’s Earth Observing-1 (EO-1) satellite.

The volcano, about 120 kilometres east of Reykjavik, erupted March 20 after almost 200 years of silence.

Watch an animation from ESA of how the plume traveled.

Pall Einarsson, a geophysicist at the University of Iceland, said magma was melting a hole in the thick ice covering the volcano’s crater, sending water coursing down the glacier, and causing widespread flooding.

Iceland’s main coastal ring road was closed near the volcano, and workers smashed a hole in the highway in a bid to give the rushing water a clear route to the coast and prevent a major bridge from being swept away.

Sources: CBC, NASA Earth Observatory, ESA

Chilean Earthquake May Have Shortened the Length of a Day on Earth

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Yikes! Just how big was the magnitude 8.8 earth quake in Chile? One scientist says the shaking may have affected the entire planet by shifting Earth on its axis. This possibly may have shortened the length of a day on Earth by about 1.26 microseconds. Using a complex model JPL research scientist Richard Gross computed how Earth’s rotation should have changed as a result of the Feb. 27, 2010 quake. If his figures are correct, the quake should have moved Earth’s figure axis (the axis about which Earth’s mass is balanced) by 2.7 milliarcseconds (about 8 centimeters, or 3 inches).

Earth’s figure axis is not the same as its north-south axis; they are offset by about 10 meters (about 33 feet). By comparison, Gross said the same model estimated the 2004 magnitude 9.1 Sumatran earthquake should have shortened the length of day by 6.8 microseconds and shifted Earth’s axis by 2.32 milliarcseconds (about 7 centimeters, or 2.76 inches).

Gross said that even though the Chilean earthquake is much smaller than the Sumatran quake, it is predicted to have changed the position of the figure axis by a bit more for two reasons. First, unlike the 2004 Sumatran earthquake, which was located near the equator, the 2010 Chilean earthquake was located in Earth’s mid-latitudes, which makes it more effective in shifting Earth’s figure axis.

Second, the fault responsible for the 2010 Chiliean earthquake dips into Earth at a slightly steeper angle than does the fault responsible for the 2004 Sumatran earthquake. This makes the Chile fault more effective in moving Earth’s mass vertically and hence more effective in shifting Earth’s figure axis.

Gross said the Chile predictions will likely change as data on the quake are further refined.

Source: JPL