Earthquakes Essay, Research Paper

Earthquakes: Causes, Mapping, and Predicting

Throughout history, adult male has made many promotions.

These promotions have been made to do life easier. The 1

thing adult male can & # 8217 ; t do is to command Mother Nature. Mother Nature can

cause many things such as temblors. The causes of temblors

have been theorized in many ways. Harmonizing to the book

Predicting Earthquakes by Gregory Vogt, the Greeks, & # 8220 ; blamed the

temblors on Poseidon, God of the sea & # 8221 ; ( 25 ) . The Hindu believed

that & # 8220 ; the Earth was a platform that rested on the dorsum of eight

great elephants. When one of the elephants grew weary, it

lowered and agitate its caput doing the land above to

tremble & # 8221 ; ( Vogt 25 ) . Margaret Poynter writes & # 8220 ; many crude people

idea that the Earth rested upon the dorsum of some kind of animate being.

When that animate being became ungratified, great clefts appeared in the

land, and tall trees swayed and fell. In South America, the animate being

was a giant. In Japan, it was a great black spider or elephantine mudcat.

One antediluvian folk thought that four bulls supported the Earth on

their horns. To divert themselves, they sometimes tossed it from one

to another & # 8221 ; ( 6 ) . In the same book, Poynter says & # 8220 ; The Chinese believed

that monsters lived in the caves inside the Earth. When the

animals fought, the surface of the Earth trembled ( 6 ) . & # 8221 ; & # 8220 ; In Greece,

it was non an animate being, but a colossus named Atlas who was condemned

to back up the universe upon his shoulders. Subsequently, about the 3rd

century B.C. , a Grecian philosopher, Aristotle, had a more scientific

account. He thought that temblors occurred merely when hot

air multitudes tried to get away from the centre of the Earth. Two

centuries subsequently, Lucretius, a Roman, wrote that resistance

landslides caused the Earth & # 8217 ; s surface to travel & # 8221 ; ( Poynter 7 ) .2 Last

Name

Today, scientists have found a more logical ground to

temblors. Scientists say about 600 million old ages ago, all the

continents were connected to organize a immense super continent called

Pangaea. At about 220 million old ages ago, Pangaea began to interrupt

up into sub-blocks. Harmonizing to the book Volcanoes, Earthquakes,

and the Formation of Continents, these sub-blocks were called

& # 8220 ; Gondwana ( which corresponds about to the continents of

the present southern hemisphere ) and Laurasia ( the Northern

hemisphere ) & # 8221 ; ( Kohler 15 ) . Harmonizing to Pierre Kohler, & # 8220 ; The Earth & # 8217 ; s

surface is divided into 13 home bases: seven big 1s ( the largest

matching to the Pacific ) and six little 1s & # 8221 ; ( 18-19 ) . The book

Earthquakes by Margaret Poynter states that a individual named

Robert Mallet studied temblors. He made trials, drew a universe

map, and recreated temblors merely to happen that stones are being

overstressed at the mistakes. & # 8220 ; A mistake is the topographic point where two home bases

meet and are rubbed against each other & # 8221 ; ( Groiler Electronic

Publishing, Inc. ) . The book, Predicting Earthquakes, the writer points

out & # 8220 ; There are by and large three sorts of mistakes: normal, contrary, and

strike-slip. By careful observation and measuring, geologists,

moving like investigators, can state how much a mistake moved, which portion

went up, which portion went down, and which manner the mistake moved & # 8221 ;

( Vogt 26 ) . & # 8220 ; When one of the home bases slip under the great sum of

emphasis at the mistake, an temblor occurs. The shaking we feel are

the passing of long moving ridges & # 8221 ; ( Putnam 443 ) . & # 8220 ; The L-waves ( long

moving ridges ) travel at slower speeds that the primary and secondary

moving ridges. These moving ridges make the largest curlicues on a seismograph

but their consequence diminishes quickly with distance. The L-waves are

limited to the crust & # 8221 ; ( Putnam 443 ) . One of the two sorts of moving ridges

are & # 8220 ; Primary moving ridges are a family to sound moving ridges, and therefore bring forth

alternate compaction and rarefaction in the medium through which

they travel much like the moving ridges that spread out through the air in

all waies from a tuning fork & # 8221 ; ( Putnam 444 ) . The second of the

two sorts of moving ridges are & # 8220 ; Secondary moving ridges, the atoms in the stone

through which the moving ridge is going vibrate at right angles, or

transversally, to the way of extension. The speed of

P-waves are about twice every bit fast as S-waves & # 8221 ; ( Putnam 444 ) . & # 8220 ; A

seismologist can non turn up the epicentre ( where the temblor

took topographic point ) of an temblor that has shown up on his

seismometer from the seismogram, or written record, entirely. All the

seismogram tells him are the times when the P and S waves reach

his station, and how violent they are & # 8221 ; ( Marcus 62 ) . Rebecca Marcus,

in her work The First Book of Volcanoes & A ; Earthquakes, explicate how

scientists locate an temblor & # 8217 ; s epicentre. & # 8220 ; To turn up a temblor, the

seismologist foremost finds the difference between the clip of reaching of

the P moving ridge and that of the S moving ridge. Let us say that an S moving ridge

reaches a station in New York on a certain day of the month at 10:30 P.M. , 4

proceedingss and

42 seconds after a P moving ridge. the seismologist so refers

to a tabular array, which tells him that the epicentre is 2,000 stat mis off.

Although he has found its distance, he does non cognize its way

from his station. & # 8220 ; Now he needs the cooperation of at least two

other Stationss. Messages are sent, allow us state, to a station in San

Francisco and to another in Rio de Janeiro, inquiring for their distance

from an temblor that occurred on that day of the month at 18

seconds past 10:25 P.M. , New York clip. When the seismologist

receives his replies, he learns that the epicentre was 3,800 stat mis

from San Francisco and 3,500 stat mis off from Rio de Janeiro. Using

a radius stand foring 2,000 stat mis, he draws a circle around New

York. Next, utilizing the same graduated table, he draws a circle with a radius

stand foring 3,800 stat mis about Riode Janeiro. The three circles cross

at a point near the Dominican Republic. And here is the epicentre of

the temblor & # 8221 ; ( 63 ) . To mensurate and place these moving ridges, an

innovation called the seismometer was used. Rebecca Marcus Tells

about the first seismograph. & # 8220 ; The really first effort to observe a

distant temblor was make about A.D. 136 in China by an

discoverer whose name was Chang Heng. Chang Heng & # 8217 ; s innovation

consisted of a big hollow ball standing on its base which was set

on degree land. A heavy weight was suspended inside the shell.

Around the big ball, at equal distances, were eight

open-mouthed bronze firedrake caputs, and on the lingua of each

was a little Cu ball. A bronzy open-mouthed frog stood

beneath each firedrake caput. The whole instrument was so ordered

that, at the slightest jarring by an temblor moving ridge, the suspending

weight would do one of the balls to hit out of the firedrake & # 8217 ; s

oral cavity into the frog & # 8217 ; s oral cavity. Which ball shooting out depended on the

nearest way of the moving ridge & # 8221 ; ( Marcus 57 ) . In today & # 8217 ; s modern universe,

engineering would do Chang Heng & # 8217 ; s seismometer expression petroleum and

untrust worthy. Today & # 8217 ; s modern seismometer looks similar but more

complicated because it involves photographic paper, a beam of

visible radiation, a mirror, and many other things. In 1935, Charles Richter

created a graduated table that measured temblors. In February 1977,

Richter & # 8217 ; s graduated table was somewhat revised because of the fact that there

are now more sophisticated ways of measuring and the graduated table

didn & # 8217 ; t cover the higher magnitude evaluation. In the book Geological

Catastrophes, by Thomas G. Aylesworth, the writer provinces: & # 8220 ; There is

another method of mensurating temblors, the modified Mercali

graduated table. This is a twelve-point graduated table of strength that grades the temblor

by depicting the sorts of harm and other effects caused by it.

You might state that the Richter graduated table measures the existent power of

the temblor, while the modified Mercali graduated table measures the

temblor & # 8217 ; s consequence on worlds. In any instance, the two graduated tables do non

give us rather the same information. Here are the 12 points that

do up the modified Mercali graduated table: I- Just detectable by

experient perceivers when prone. Microseisms ( bantam quivers ) .

2-Felt by few. Finely poised objects may rock. 3- Vibration, but

still unrecognized by many. Feeble. 4- Felt by many indoors but by

few out-of-doorss. Moderate 5- Felt by about all. Many awakened.

Unstable objects moved. 6-I Felt by all. Heavy objects moved. Alarm.

Strong. 7- General dismay. Weak edifices well damaged.

Very strong. 8- Damage general except in proofed edifices. Heavy

objects overturned. 8- Buildings shifted from foundations, prostration,

land clefts. Highly destructive. 10- Masonry edifices destroyed,

tracks set, serious land crevices. Lay waste toing. 11 Few if any

constructions left standing. Bridges down. Rails twisted. Catastrophic. 12

Damage sum. Vibrations distort vision. Objects thrown in air. Major

calamity & # 8221 ; ( 14-15 ) . In the book Earthquake by Bryce Walker there

is an article that explains how to foretell temblors. Most of the

theories involve the other planets run alonging up and seting great emphasis

on the Earth which causes temblors. & # 8220 ; I think that all of the oil

and soft decorations that we are taking is making clash and causation

the temblors in California & # 8221 ; . In, When Nature Runs Wild, the

writer provinces that & # 8220 ; At the present clip, adult male can non foretell

temblors. Several states, nevertheless, have research plans

that are look intoing these jobs. Leaderships in this field are the

United States, Japan, and the Soviet Union & # 8221 ; ( Johnson 12 ) . The World

Book Encyclopedia, writes that & # 8220 ; Scientists can do reasonably accurate

long-run anticipations of where temblors will happen. They know,

for illustration, that about 80 per centum of the universe & # 8217 ; s major

temblors happen along a belt encircling the Pacific Ocean. This

belt is sometimes called the Ring of Fire because it has many

vents, temblors, and other geologic activity & # 8221 ; ( Earthquakes ;

Karen C. McNally 38 ) .