EARTH SCIENCES - Notable Research and Discoveries Part 9 potx

earth ScienceS1 tem needs enough sensors to cover a broad area so that there is a good chance an earthquake will be de-tected early; an earthquake aris-ing between detectors situated too

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tem needs enough sensors to cover

a broad area so that there is a good chance an earthquake will be de-tected early; an earthquake aris-ing between detectors situated too sparsely would travel a long time before being noticed, and the warn-ing would come too late for people who lived nearby Japan’s system employs about 1,000 sensors buried underground The sensors transmit information to a computer network that monitors and analyzes the data

A few seconds after an earthquake, the computer estimates the location and intensity and sends a warning to the affected region if the earthquake

is serious enough to pose a threat

The alarm goes out on the major television and radio channels In-structions are also provided to pre-vent a panic, such as a massive rush for the exits in crowded buildings

mated; for example, switches to shut off heavy machinery and elevators

issued in April 2008 for an earthquake on the island of Okinawa having an

approximate magnitude of 5.2, came a few seconds too late to provide ade-quate warning The earthquake was minor, though, and did little damage

Warning systems are also necessary for tsunamis No alarms went out during the Indian Ocean tsunami of 2004, which caught everyone

off guard Undersea earthquakes cause these giant waves by disturbing

A technician at the

Geotechnic Research Center

in San Salvador, El Salvador,

monitors seismometer

recordings (Yuri Cortez/

AFP/Getty Images)

Researchers have begun looking into this possibility In 2002 Ka-Science and Disaster Prevention (NIED) in Japan, recorded unusual

activity may occur in the future For example, foreshocks preceding a

major earthquake may have particular patterns at particular faults, and

which minor earthquakes will probably be followed by a major one

But past performance is not necessarily a predictor of the future (as stockbrokers and mutual fund managers often say) Most geologists use

little scientific training are working toward this goal Motivating some

of these people, at least to a certain extent, is the prospect of making a

great deal of money if a successful prediction scheme is patented and sold

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Inaccurate predictions either give a false sense of security when they fail to predict an earthquake or raise a false alarm when they predict an

earthquake that does not show up The stakes are high

Some researchers are pessimistic about ever developing a reliable method for predicting earthquakes Similar to stock markets and weath-

The Parkfi eld earthquake prediction missed the mark by about

11 years, but the widely anticipated event drew the attention

and instrumentation of about 100 earthquake researchers

to the area After nearly 20 years of experience at the San

Andreas Fault near Parkfi eld, researchers decided to probe

deeper In the summer of 2002, researchers drilled a

1.4-mile (2.2-km) vertical hole near (but not at) the fault Funding

this work was the International Continental Scientifi c Drilling

Program, a multinational effort to promote geological

stud-ies involving drilling This hole was a pilot project, designed

to test researchers’ equipment and their capacity to conduct

experiments at the fault itself After its success,

research-ers began drilling a deeper hole in June 2004, to install

instruments into and across the fault.

This project is called the San Andreas Fault tory at Depth While much seismological research relies

Observa-on instruments placed at the surface or not far below, this

project aimed to monitor fault movement deep below the

surface The National Science Foundation (NSF), one of the

surface moves by that amount, a satellite using this equipment can de-tect it by comparing its present location with previous images or maps

Satellite imagery, along with data and tools discussed earlier in this chapter, have been integrated into an earthquake model program called

During several phases of the project, researchers lected sample cores (cylindrical sections of rock cut out by

col-a drill pipe) As geologists col-ancol-alyze the chemiccol-al composition and mechanical properties, they will learn more about the stresses to which rocks at the fault are subjected This infor- mation is vital because ruptures in this area are the source

of major earthquakes In September 2007, the drill team finished up at the site by installing instrumentation at about 10,500 feet (3,200 m) The instruments included seismom- eters, accelerometers to measure sudden movement, tilt- meters to measure angle, and a pressure transducer Over the coming years, data collected from this site will give ge- ologists a glimpse of the mechanisms acting directly inside the fault.

1 The German scientist Emil Wiechert (1861–1928)

out an earthquake episode (without breaking!)

fashions a seismometer that is able to record through-10 The Italian researcher Giuseppe Mercalli (1850–

1914) designs a scale to measure earthquake intensity based on eyewitnesses and observational evidence

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A powerful earthquake strikes San Francisco, Cali-fornia, damaging buildings and causing fires that destroyed much of the city and claimed about 3,000 lives

1 The American seismologist Charles Richter (1900–

85) and the German-American seismologist Beno Gutenberg (1889–1960) develop an earthquake magnitude scale based on the amplitude of the vi-brations as measured by their seismograph

1 Chinese scientists observe surface deformation and

ate the city of Haicheng A day later, an earthquake

other signs of an impending earthquake and evacu-of magnitude 7.3 on the Richter scale strikes, but the city suffers few casualties due to the early warning

1 An earthquake of magnitude 7.8 on the Richter

scale hits the Chinese city of Tangshan without warning, killing about 250,000 people in one of the worst natural disasters of the 20th century

1 The American seismologist Thomas Hanks and the

Japanese seismologist Hiroo Kanamori introduce the moment magnitude scale for earthquake inten-sity, which most seismologists now prefer to use

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Japan completes installation of a network of seis-mic sensors in the attempt to provide its citizens with at least a few seconds warning before a major earthquake hits

USGS staff finish placing seismic monitoring instru-ments deep within the San Andreas Fault, part of the San Andreas Fault Observatory at Depth project

00 USGS announces an earthquake forecast that

warns of a 99 percent probability of an earthquake

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of magnitude 6.7 Mw or greater in California in the next 30 years

Hough, Susan Elizabeth Earthquaking Science: What We Know (and

Don’t Know) about

Ulin, David L The Myth of Solid Ground: Earthquakes, Prediction, and

the Fault Line Between Reason and Faith New York: Viking, 2004

Winchester, Simon A Crack in the Edge of the World: America and

the Great California Earthquake of 1906 New York: HarperCollins,

2005 The disastrous 1906 earthquake left San Francisco mostly rub-ble, as buildings collapsed and fires raged out of control Winchester

revisits the carnage and discusses the subsequent geological investi-gation of the San Andreas Fault

sing, which would have contained carbon dioxide, nitrogen, hydrogen, water vapor, and a few other substances Hydrogen is so light that some

of it escaped, and some of it combined with carbon or nitrogen to form methane or ammonia, among other hydrogen-containing compounds

Oxygen came later, as a by-product of the photosynthesis of plants

Th e exact composition of the early atmosphere is unknown, but

der Professor Harold Urey (1893–1981) at the University of Chicago, reported an astonishing experiment in which he assumed the early at-mosphere had abundant hydrogen compounds (Hydrogen-rich atmo-spheres are called reducing atmospheres, since their chemistry would involve reducing reactions, as opposed to oxidizing reactions.) Miller put water, hydrogen, methane, ammonia, and carbon monoxide in a sterilized fl ask and then exposed the contents to electric sparks that simulated lightning Th e water turned brown a few weeks later Analyz-ing the contents, he found a large number of organic—carbon-contain-ing—compounds, including several diff erent types of amino acids, the building blocks of proteins

in 1953 Stanley Miller (1930–2007), a graduate student studying un-Th e experiments of Miller and Urey suggested that molecules critical for life could have developed from simple reactions in a reducing envi-ronment Although the experiments did not create life itself, they sug-gested how the vital components could have arisen Interactions among these components presumably led to life, some time in the distant past

But Earth may not have had such a reducing atmosphere in its early days Some researchers have returned to the experiments of Miller and Urey, but with the focus on a specifi c instigator—volcanic activity

ogy Institute at Indiana University, and Jeff rey L Bada at the Scripps Institution of Oceanography came across some material left over from Miller’s 1950s experiments Miller had moved to the University of Cali-fornia, San Diego, in 1960, and Bada was a graduate student in his labo-ratory in 1965–68 In an interview for a NASA press release on October

Adam P Johnson, a graduate student with the NASA Astrobiol-ects until he died in 2007 When Adam and I found the samples from the original experiments, it was a great opportunity to reanalyze these historic samples using modern methods.”

16, 2008, Bada said, “Stanley and I continued to work on various proj-tions by injecting steam into the apparatus Johnson, Bada, and their

perplexing question at the frontier of science Progress toward a solu-

tion of this mystery would help people learn a great deal about the na-ture of living organisms Perhaps life is an inevitable process, which

changes Earth is currently experiencing, this issue might be the most

relevant of all