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Natural Disasters: Earthquakes & Volcanoes

An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. Earthquakes are recorded with a seismometer, also known as a seismograph. The moment magnitude of an earthquake is conventionally reported, or the related and mostly obsolete Richter magnitude, with magnitude 3 or lower earthquakes being mostly imperceptible and magnitude 7 causing serious damage over large areas. Intensity of shaking is measured on the modified Mercalli scale.

At the Earth's surface, earthquakes manifest themselves by a shaking and sometimes displacement of the ground. When a large earthquake epicenter is located offshore, the seabed sometimes suffers sufficient displacement to cause a tsunami. The shaking in earthquakes can also trigger landslides and occasionally volcanic activity.

In its most generic sense, the word earthquake is used to describe any seismic event—whether a natural phenomenon or an event caused by humans—that generates seismic waves. Earthquakes are caused mostly by rupture of geological faults, huge amounts of gas migration, mainly methane deep within the earth, but also by volcanic activity, landslides, mine blasts, and nuclear experiments.

A volcano is an opening, or rupture, in a planet's surface or crust, which allows hot, molten rock, ash, and gases to escape from below the surface. Volcanic activity involving the extrusion of rock tends to form mountains or features like mountains over a period of time.

Volcanoes are generally found where tectonic plates are pulled apart or come together. A mid-oceanic ridge, for example the Mid-Atlantic Ridge, has examples of volcanoes caused by "divergent tectonic plates" pulling apart; the Pacific Ring of Fire has examples of volcanoes caused by "convergent tectonic plates" coming together. By contrast, volcanoes are usually not created where two tectonic plates slide past one another. Volcanoes can also form where there is stretching and thinning of the Earth's crust, such as in the African Rift Valley, the Wells Gray-Clearwater Volcanic Field and the Rio Grande Rift in North America and the European Rhine Graben with its Eifel volcanoes.

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16 Items found Print
Amazing Earth Model Book
by Donald M. Silver, Patricia J. Wynne
from Scholastic Inc.
for 3rd-6th grade
in Geology (Rocks & Minerals) (Location: BSR-04B)
$2.00 (1 in stock)
Best Book of Volcanoes
1st edition from Kingfisher
for 4th-6th grade
$3.00 (1 in stock)
Disaster Preparedness Flipper
from Christopher Lee Publications
for 5th-Adult
in Home Economics Curriculum (Location: C08-07D)
Earth Shook, the Sky Burned
by William Bronson
from Chronicle Books
for 6th-Adult
in Titanic & 20th Century Disasters (Location: B01-22D)
$4.20 (1 in stock)
Earthquake at Dawn
by Kristiana Gregory
from Gulliver Books
for 4th-6th grade
in Historical Fiction (Location: A05-01A)
$2.00 (2 in stock)
by Franklyn M. Branley
from HarperTrophy
for Preschool-3rd Grade
$2.00 (2 in stock)
Janice VanCleave's Volcanoes
by Janice VanCleave
from John Wiley & Sons, Inc.
for 4th-8th grade
in Clearance: Science & Health (Location: ACL-SCI)
$2.00 (1 in stock)
Mountain of Fire
Creation Adventure
by Paul Thomsen
from Institute for Creation Research
for 5th-9th grade
in Adventure Stories (Location: A04-01A)
$2.10 (2 in stock)
Mountains and Volcanoes
Young Discoverers
by Barbara Taylor
from Kingfisher
for Preschool-3rd Grade
$2.00 (1 in stock)
Nature's Fury
by Carole G. Vogel
from Scholastic Inc.
for 4th-8th grade
$2.00 (1 in stock)
See-Through Storms
by Gill Paul
from Running Press
for 3rd-6th grade
in Meteorology (Weather & Climate) (Location: BSR-03C)
$3.00 (1 in stock)
by Patricia Lauber
from Scholastic Inc.
for 4th-7th grade
$3.00 (2 in stock)
by Patricia Lauber
from Simon and Schuster
for 3rd-6th grade
$2.00 (1 in stock)
Volcano - Mount St. Helens, 1980
by Robert D. Shangle
12th edition from Beautiful America Publishing
for 7th-12th grade
in Clearance: Science & Health (Location: ACL-SCI)
$2.00 (1 in stock)
Volcanoes and other Natural Disasters
A DK Eyewitness Reader Level 4
by Harriet Griffey
from DK Publishing
for 2nd-4th grade
in DK Readers (Location: CPB-05D)
$1.75 (1 in stock)
A Step into Reading Book Level 4
by Eric Arnold
from Random House
for 2nd-3rd grade
in Step into Reading (Location: CPB-05D)