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1 Mudslide
in Ecuador
2 Listening
to undersea quakes
3 Asian
dust travels half way around the world
4 Mississippi
flooding
5 Liquefaction
seen after earthquake
1
Mudslide in Ecuador
In the early
morning of June 12, a mudslide inundated a home in Papallacta, Ecuador
engulfing and killing 30 or more people who had taken refuge there.
The heavy rains that caused the slide ceased while rescue workers dug away
the mud in search of victims.
www.cnn.com/2001/WORLD/americas/06/14/ecuador.landslide.ap/index.html
2
Listening to undersea quakes
A volcanic eruption off the Oregon coast on April 3 set off a sequence
of minor earthquakes as injected magma cracked apart an underwater ridge.
More than 3,500 tremors were recorded in the first week after the eruption,
with the largest earthquake detected measuring magnitude 4.5. The eruption
took place on the Jackson segment of the undersea Gorda Ridge formation,
130 miles from the coast and 50 miles south of a similar 1996 eruption
on the ridge’s Northern Gorda segment.
National Oceanic and Atmospheric Administration (NOAA) scientists checking the ocean floor for seismicity caught the noise of the eruption using a modified version of the U.S. Navy’s once top-secret array of submarine tracking hydrophones. The rumbling can be heard online at www.pmel.noaa.gov/vents/acoustics/seismicity/nepac/gordaridge01.html. This was the fourth eruption identified off Oregon’s coast since NOAA began using the hydroacoustic monitoring system in 1993.
3
Asian dust travels half way around the world
Jet-stream winds picked up sub-micron sized sand, animal bones, parts
of mummified ancient humans and other items lost over time in Mongolia's
Gobi Desert and China's Taklimakan Desert and blew the dusty remains across
the Pacific Ocean in as little as four days in early April. Satellite images
showed a thick, yellow swirl of dust streaming out across Korea and the
Pacific Ocean. Usually clouds and weather systems cause such dust storms
to fizzle out, but this one held together and toured North America, beginning
with the West Coast on April 12. The cloud amazed Russ Schnell — director
of observatory operations for NOAA's Climate Monitoring and Diagnostics
Laboratory in Boulder, Colo. — who has been monitoring Asian dust storms
for 20 years. "This was the first storm I've seen that crossed the whole
United States and went on to the Atlantic Ocean," Schnell says. A layer
of dust descended on parts of Canada and as far south as Arizona as it
made its way east. In Colorado, where the plume lingered from April 14-18,
the haze was about four miles thick. On April 19, the cloud stretched from
Hudson Bay to northern Florida, as it trickled out over the East Coast.
Events like this can carry urban pollution along with the dust as they
move, a warning that "we are all downwind of someone else's pollution,"
Schnell says.
4
Mississippi flooding
Towns along
the Mississippi River and its tributaries loaded up their levees with sandbags
when melting snow and two heavy rainstorms brought floods to the Midwestern
United States in mid-April. Some 4,400 people were displaced with damages
estimated to cost $13 million. The Mississippi River crested at 22.32 feet
near Davenport, Iowa, on April 23. Flood stage is 15 feet. The highest
level on record is from 1993 when the river reached 22.63 feet.
5
Liquefaction seen after earthquake
This view from NASA’s Shuttle Radar Topography Mission (SRTM) was taken
April 26, three months after the magnitude-7.7 earthquake that struck India.
The region of the epicenter appears in the lower left corner. In the foreground
is the southern Rann of Kachchh, an area of low-lying salt flats that shows
up with various shades of white and blue in this false-color Landsat image.
The gray area in the middle of the image is called the Banni plains.
The darker blue spots and curving lines in the Rann and the Banni plains are features that appeared after the earthquake. Their true colors are shades of white and gray, but the infrared data used in the image gives them a blue or turquoise color. These features are the effects of liquefaction of wet soil, sand and mud layers caused by the shaking of the earthquake. The liquefaction beneath the surface causes water to be squeezed out at the surface, forming mud volcanoes, sand blows and temporary springs. Some of the residents of this dry area hoped they could use the water, but they found that the water was too salty in almost every place it surfaced.
The city of Bhuj appears as a gray area in the upper right of the image.
The red hills in the center of the image are the Has and Karo Hills, which
reach up to 300 meters (900 feet) elevation. Geologists are studying the
folded red sandstone layers that form these hills to determine if they
are related to the blind fault that broke during the earthquake.
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