Monday, May 31, 2010

Fault Types

A fault is a large crack in the Earth's crust where one part of the crust has moved against another part. This movement means that faults prove the Earth is an active place. They are signs of powerful forces deep underground.

The parts of a fault are (1) the fault plane, (2) the fault trace, (3) the hanging wall and (4) the footwall. The fault plane is is a flat surface that may be vertical or sloping. The line it makes on the Earth's surface is the fault trace. Where the fault plane is sloping, the upper side is the hanging wall and the lower side is the footwall. When the fault plane is vertical, there is no hanging wall or footwall. 

Any fault plane can be completely described with two measurements: its strike and its dip. The strike is the direction of the fault trace on the Earth's surface. The dip is the measurement of how steeply the fault plane slopes—if you dropped a marble on the fault plane, it would roll exactly down the direction of dip.

U.S. Geological Survey image
It's important to know a fault's type: normal, reverse or strike-slip. The type reflects the kind of forces that are acting on the fault.

Normal faults form when the hanging wall drops down. The forces that create normal faults are pulling the sides apart, or extensional.

Reverse faults form when the hanging wall moves up. The forces creating reverse faults are compressional, pushing the sides together.

Together, normal and reverse faults are called dip-slip faults, because the movement on them occurs along the dip direction—either down or up, respectively.

Strike-slip faults have walls that move sideways, not up or down. That is, the slip occurs along the strike, not up or down the dip. In these faults the fault plane is usually vertical, so there is no hanging wall or footwall. The forces creating these faults are lateral or horizontal, carrying the sides past each other.

Strike-slip faults are either right-lateral or left-lateral. That means someone standing near the fault trace and looking across it would see the far side move to the right or to the left, respectively. The one in the picture is left-lateral.

In reality, many faults show a combination of dip-slip and strike-slip motion. Geologists use more sophisticated measurements to analyze these fault movements. The Natural Fractures site has a page with more rigorous detail on these.

You can judge a fault's type from looking at the focal mechanism diagrams of earthquakes that occur on it—those are the "beachball" symbols you'll often see on earthquake sites.

SOFIA Sees Jupiter's Ancient Heat

The Stratospheric Observatory for Infrared Astronomy, or SOFIA, took off for its maiden flight during the early hours of Wednesday morning and the "first light" images of the observations taken during the flight are available.

Already, the flying telescope has spotted something that has never been seen before: ancient heat leaking through the clouds of Jupiter.
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Mitigating the Effects of El Niño

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"Top Kill" Fails

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Friday, May 28, 2010

Electric Ash Found in Eyjafjallajokull's Plume, Say UK Researchers

 In the first peer-reviewed scientific paper to be published about the Icelandic volcano since its eruption in April 2010, UK researchers write that the ash plume which hovered over Scotland carried a significant and self-renewing electric charge.
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Tuesday, May 25, 2010

China to put up its own GPS by 2012

Challenging US monopoly on global positioning systems (GPS), China is set to establish its own satellite navigation system by 2012, covering the Asia-Pacific region. China will become the third country, after US and Russia (it's system is under restoration), to have its own 'sat nav', a Chinese scientist has announced. Sun Jiadong, chief designer of the Beidou Navigation System, indicated China was ready to spend several billion dollars to put up a network of 30 new satellites in the sky. The local government was looking for markets to sell navigational services in order to finance the project, he said.

Monday, May 24, 2010

Delhi's hi-tech pollution control drive begins

In a bid to make the city's air cleaner before the Commonwealth Games, the Delhi government will launch a special drive  against polluting commercial and private vehicles using latest technology.
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Philips Unveils World's First 60 Watt LED Bulb

At the Lightfair International tradeshow in Las Vegas, Royal Philips Electronics unveiled its breakthrough EnduraLED light bulb. This bulb will be the world's first LED replacement for the 60 watt incandescent light bulb, which represents about half of all domestic incandescent light bulbs sold on the market.The EnduraLED lamp will use only 12 watts, last 25 times longer, and deliver up to eighty percent savings on energy costs and avoided maintenance costs. However, the new bulb will produce a light level of 806 lumens, similar to the 60 watt incandescent. To achieve this efficiency, it uses an innovative design and a new technology known as remote phosphor technology, developed by Philips researchers in The Netherlands.

Sunday, May 23, 2010

Geely to Produce Cheaper City Car Than Tata Nano

Chinese automaker Geely is planning to produce a budget city car expected to cost less than the Indian-made Tata Nano.

The new Geely IG is slated to sell for about US$2,250, comparable in price to the US$2,700-US$3,800 Nano, and will go on sale in China in 2012.

Ariane rocket launches two satellites

An Ariane rocket has orbited two telecommunications satellites after a launch from French Guiana .
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Saturday, May 22, 2010

Artificial life: Manmade DNA powers cell

Scientists announced a bold step Thursday in the enduring quest to create artificial life. They've produced a living cell powered by manmade DNA.
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Iceland Volcano Blows Spectacular Smoke Ring

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Wednesday, May 19, 2010

Six men get ready for 520-day simulated Mars trip

Six men from Russia, Europe and China are preparing to spend 520 days together in a sealed-off warren to take a simulated trip to Mars to test how long isolation would affect humans.
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Monday, May 17, 2010

अग्नि-2 का रात में पहली बार परीक्षण

 परमाणु हथियार ले जाने में सक्षम मध्यम दूरी की बैलेस्टिक मिसाइल (आईआरबीएम) अग्नि-2 का पहली बार रात में परीक्षण किया गया। इस मिसाइल को उड़ीसा के समुद्री तट से दूर स्थित ह्वीलर आइलैंड से सोमवार रात्रि करीब 7:50 बजे छोड़ा गया। देश के इतिहास में इससे पहले किसी मिसाइल का रात में कभी भी परीक्षण नहीं किया गया।

एकीकृत परीक्षण क्षेत्र (आईटीआर) के सूत्रों ने यह जानकारी दी। रात्रिकालीन परीक्षण इस मिसाइल को स्ट्रैटेजिक फोर्स कमांड में पूर्णत: इस्तेमाल करने के लिए सक्षम बनाने के लिहाज से महत्वपूर्ण कदम है। इसे आईटीआर के लांच कॉम्पलेक्स-4 से रेल मोबाइल प्रणाली के जरिए छोड़ा गया।

रक्षा से जुड़े एक सूत्र ने यह जानकारी दी। इस परीक्षण के साक्षी रहे रक्षा अधिकारी ने बताया, ‘अभियान से जुड़ी विभिन्न कसौटियों से संबंधित आंकड़ों का विश्लेषण किया जा रहा है।’अग्नि-2 को पहले ही सेवा में शामिल किया जा चुका है। यह 2,000 किलोमीटर से अधिक दूरी तक मार करने में सक्षम है।

Mount St. Helens

Mount St. Helens is an active volcano located in the United States' Pacific Northwest region. It is about 96 miles (154 km) south of Seattle, Washington and 50 miles (80 km) northeast of Portland, Oregon. Mount St. Helens is a part of the Cascade Mountain Range which runs from northern California through Washington and Oregon and into British Columbia, Canada. The range features many active volcanoes because it is a part of the Pacific Ring of Fire and the Cascadia Subduction Zone which has formed as a result of converging plates along the North American coast. Mount St. Helens' most recent period of eruptions lasted from 2004 to 2008, although its most devastating modern eruption occurred in 1980 (images). On May 18 of that year, Mount St. Helens erupted, causing a debris avalanche which took off the top 1,300 feet of the mountain and destroyed the forest and cabins around it. Today, the land surrounding Mount St. Helens is rebounding and most of it has been preserved as a part of the Mount St. Helens National Volcanic Monument. Geography of Mount St. Helens Compared to other volcanoes in the Cascades, Mount St. Helens is fairly young geologically speaking because it formed only 40,000 years ago. Its top cone that was destroyed in the 1980 eruption began forming only 2,200 years ago. Because of its quick growth, many scientists consider Mount St. Helens the most active volcano in the Cascades within the last 10,000 years. There are also three main river systems in the vicinity of Mount St. Helens. These rivers include the Toutle, Kalama and Lewis Rivers. This is significant because the rivers (especially the Toutle River) were impacted in its eruption. The nearest town to Mount St. Helens is Cougar, Washington, which is around 11 miles (18 km) from the mountain. The rest of the area is surrounded by the Gifford Pinchot National Forest. Castle Rock, Longview and Kelso, Washington were also affected by the 1980 eruption however because they are low-lying and near the region's rivers. The nearest main highway in and out of the area is State Route 504 (also called the Spirit Lake Memorial Highway) which connects with Interstate 5. 1980 Eruption As previously mentioned, the most recent large eruption of Mount St. Helens took place in May of 1980. Activity on the mountain began on March 20, 1980 when a magnitude 4.2 earthquake struck. Shortly thereafter, steam began to vent from the mountain and by April, the north side of Mount St. Helens began to grow a bulge. Another earthquake struck on May 18 which caused a debris avalanche that wiped out the entire north face of the mountain. It is believed that this was the largest debris avalanche in history. Following the avalanche, Mount St. Helens eventually erupted and its pyroclastic flow leveled the surrounding forest and any buildings in the area. Over 230 square miles (500 sq km) was within the "blast zone" and was affected by the eruption. The heat from Mount St. Helens' eruption and the force of its debris avalanche on its northern side caused the ice and snow on the mountain to melt which formed volcanic mudflows called lahars. These lahars then poured into the surrounding rivers (the Toutle and Cowlitz in particular) and led to the flooding of many different areas. Material from Mount St. Helens was also found 17 miles (27 km) south in the Columbia River along the Oregon-Washington border. Another problem associated with Mount St. Helens' 1980 eruption was the ash it generated. During its eruption, the plume of ash rose as high as 16 miles (27 km) and quickly moved east to eventually spread around the world. The eruption of Mount St. Helens killed 57 people, damaged and destroyed 200 homes, wiped out the forest and popular Spirit Lake and killed around 7,000 animals. It also damaged highways and railroads. Although the most significant eruption of Mount St. Helens occurred in May of 1980, activity on the mountain continued until 1986 as a lava dome began forming in the newly formed crater at its summit. During this time, many small eruptions occurred. Following those events from 1989 to 1991, Mount St. Helens continued erupting ash. Post-Eruption Natural Rebound What was once an area that was completely scorched and knocked down by the eruption is today a thriving forest. Just five years after the eruption, surviving plants were able to sprout through the build-up of ash and debris. Since 1995, there has been a growth in the variety of plats within the disturbed area and today, there are many trees and shrubs growing successfully. Animals have also returned to the region and it is again growing to be a diverse natural environment (images). 2004-2008 Eruptions Despite these rebounds, Mount St. Helens continues to make its presence known in the region. From 2004 to 2008, the mountain was again very active and several eruptions occurred, although none were particularly severe. Most of these eruptions resulted in the building up of the lava dome on Mount St. Helens' summit crater. In 2005 however, Mount St. Helens erupted a 36,000 foot (11,000 m) plume of ash and steam. A minor earthquake accompanied this event. Since these events ash and steam have been visible on the mountain several times in recent years. 
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Saturday, May 15, 2010

Easter Island Mysteries

There are many mysteries about this small island in the southeast Pacific. The biggest ones are about the strange large statutes and how they were moved about and the second about how it all ended on this lonely island. Archaeologists have now disproved the fifty year old original theory underpinning our understanding of how the famous stone statues were moved around Easter Island. Fieldwork led by researchers at University College London and The University of Manchester, has shown the remote Pacific island’s ancient road system was primarily ceremonial and not solely built for transportation of the figures.

Thursday, May 13, 2010

X-Ray Discovery Points to Location of Missing Matter in Universe

Using observations with NASA's Chandra X-ray Observatory and ESA's XMM-Newton, astronomers have announced a robust detection of a vast reservoir of intergalactic gas about 400 million light years from Earth. This discovery is the strongest evidence yet that the "missing matter" in the nearby Universe is located in an enormous web of hot, diffuse gas.

Wednesday, May 12, 2010

Drifting satellite threatens US cable programming

A TV communications satellite is drifting out of control thousands of miles above the Earth, threatening to wander into another satellite's orbit and interfere with cable programming across the United States, the satellites' owners said Tuesday.
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Stronger evidence pollution damages the heart

The evidence is stronger than ever that pollution from industry, traffic and power generation causes strokes and heart attacks, and people should avoid breathing in smog, the American Heart Association said on Monday.

Fine particulate matter from burning fossil fuels such as gasoline, coal and oil is the clearest offender, the group said.
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Tuesday, May 11, 2010

Farmers better equipped to deal with climate change

Soon farmers would get a protective knowledge cover to save them from the vagaries of weather. They are going to get long term weather pattern predictions based on which they can firm up their cropping decisions.
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Friday, May 7, 2010

Mussoorie buildings unsafe

Tourists and residents in the hill resorts of Mussoorie and Nainital in Uttarakhand, which fall under the high seismic zones, may be living on the edge.Under the European Macroseismic Scale (EMS-98), grade IV and V are important for vulnerability and risk assessment as these have the potential of threatening lives of the occupants. Since Mussoorie falls in zone IV of seismic risk map of India, the scale of damage during an earthquake might be very high.
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Sunday, May 2, 2010

Why Should We Care About the Sun?

 We certainly can't control the sun, but we can gain a deeper understanding of the sun and better predict these events. Then we can brace our power grids, send the astronauts to a shielded compartment, power down vulnerable satellites, and patiently wait for the storm to subside. SDO's super high-resolution images and spectra, magnetic field mapping, and variability monitoring are sure to give us an edge with our life-giving, but fickle, star...
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