There are thousands of earthquakes each year. Most are small, but about 1 in 500 causes damage. Some quakes are incredibly powerful and destructive. WHAT CAUSES EARTHQUAKES? E E A A R R T T HQ HQ U U A A K K E E S S DISASTERS b What is the wind speed in a Category 4 hurricane? PAGE 69 To understand earthquakes, imagine Earth as an egg with a cracked shell. The cracked outer layer (the eggshell) is called the lithosphere, and it is divided into huge pieces called plates (see map). The plates are constantly moving away from, toward, or past one another. Earthquakes result when plates collide or scrape against each other. The cracks in the lithosphere are called faults. Many quakes occur along these fault lines. CALIFORNIA’S SAN ANDREAS FAULT Perhaps the most famous fault in the world, the San Andreas fault runs for about 700 miles north-south through California. Along this fault, which is about 10 miles deep, the North American and Pacific Ocean plates are scraping past each other. In some parts of California, a crack in the ground can be seen where the fault is located. The San Andreas fault is responsible for some of the worst earthquakes in U.S. history, including the 1906 quake in San Francisco that caused more than 3,000 deaths and destroyed large parts of the city. North America South America Africa Europe Asia Antarctica Australia Pacific Ocean Pacific Ocean 66
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There are thousands of earthquakes each year. Most are small, but about 1 in 500 causes damage. Some quakes are incredibly powerful and destructive.
WHAT CAUSES EARTHQUAKES?
EEAARRTTHQHQUUAAKKEESSDISASTERS
b What is the wind speed in a Category 4 hurricane? PAGE 69
To understand earthquakes, imagine Earth as an egg with a cracked shell. The cracked outer layer (the eggshell) is called the lithosphere, and it is divided into huge pieces called plates (see map). The plates are constantly moving away from, toward, or past one another. Earthquakes result when plates collide or scrape against each other. The cracks in the lithosphere are called faults. Many quakes occur along these fault lines.
CALIFORNIA’S SAN ANDREAS FAULTPerhaps the most famous fault in the world, the San Andreas fault runs for about 700 miles north-south through California. Along this fault, which is about 10 miles deep, the North American and Pacific Ocean plates are scraping past each other. In some parts of California, a crack in the ground can be seen where the fault is located. The San Andreas fault is responsible for some of the worst earthquakes in U.S. history, including the 1906 quake in San Francisco that caused more than 3,000 deaths and destroyed large parts of the city.
1755 Lisbon, Portugal Three earthquakes struck Portugal’s capital, creating a tsunami with waves 100 feet high.
60,000
1782 South China Sea near Taiwan
After a major underwater earthquake, a tsunami sent waves inland more than 60 miles.
40,000
1883 Indonesia The Krakatau, or Krakatoa, volcano erupted four times, causing a massive tsunami more than 100 feet tall.
36,000
1908 Southern Italy A major earthquake triggered a devastating tsunami.
72,000
2004 Indian Ocean After a 9.1-magnitude earthquake hit Indonesia, a tsunami with waves up to 100 feet high struck 14 countries.
227,898
2011 Northeastern Japan
A 9.0-magnitude earthquake touched off a huge tsunami.
20,896
Year Location MagnitudeDeaths
(estimated)
1960 near Chile 9.5** 1,6551970 Northern Peru 7.9 70,0001976 Tangshan, China 7.5 242,7691988 Soviet Armenia 6.8 25,0001989 United States (San Francisco area) 6.9 631990 Western Iran 7.4 40,000+1999 Western Turkey 7.6 17,000+2001 Western India 7.6 20,0852004 Sumatra, Indonesia 9.1 227,8982005 Pakistan and India 7.6 86,0002008 Sichuan, China 7.9 87,8572010 Haiti 7.0 316,0002011 Northeastern Japan 9.0 20,896
WHAT ARE TSUNAMIS?Tsunami (pronounced tsoo-NAH-mee) comes from two Japanese words: “tsu” (harbor) and “nami” (wave). Tsunamis are huge waves. They are sometimes called tidal waves, but they have nothing to do with the tides. The strongest tsunamis happen when a big part of the sea floor lifts along a fault, pushing up a huge volume of water. Many times this happens after an undersea earthquake.
A volcano is a mountain or hill (cone) with an opening on top known as a crater. Hot melted rock (magma), gases, and other material from inside Earth mix together and rise up through cracks and weak spots. When enough pressure builds up, the magma can escape. It erupts through the crater and sometimes through smaller openings called side vents. Magma that comes out of a volcano is called lava. Lava may be hotter than 2,000°F. The cone of a volcano is often made of layers of lava and ash that have erupted, then cooled.
Some Famous Volcanic Eruptions
Year Volcano (place)Deaths
(estimated)79 Mount Vesuvius (Italy) 16,0001586 Kelut (Indonesia) 10,0001792 Mount Unzen (Japan) 14,5001815 Tambora (Indonesia) 10,0001883 Krakatau, or Krakatoa
(Indonesia)36,000
1902 Mount Pelée (Martinique) 28,0001980 Mount St. Helens (U.S.) 571982 El Chichón (Mexico) 1,8801985 Nevado del Ruiz (Colombia) 23,0001986 Lake Nyos (Cameroon) 1,7001991 Mount Pinatubo (Philippines) 800
What happened at POMPEII? Two thousand years ago, at the time of the Roman Empire, Pompeii was a vacation resort. Located near the Bay of Naples in Italy, it was popular with wealthy Romans. In A.D. 79, nearby Mount Vesuvius, an active volcano, erupted. The eruption sent huge amounts of hot rock, gases, and dense ash over the unsuspecting city. Thousands of people died, and the city was buried under millions of tons of ash. The incredibly well-preserved ruins were rediscovered in 1748, and today millions of people visit Pompeii each year.
Where is the RING OF FIRE?The hundreds of active volcanoes near the edges of the Pacific Ocean make up what is called the Ring of Fire. They mark the boundary between the plates under the Pacific Ocean and the plates under the surrounding continents. (Earth’s plates are explained on page 66, with the help of a map.) The Ring of Fire runs from Alaska, along the west coast of North and South America, to the southern tip of Chile. The ring also runs down the east coast of Asia. Starting in the far north, it passes through Russia, Japan, the Philippines, and New Guinea. It continues down past Australia. Some of the most destructive volcanic eruptions ever recorded have occurred along the Ring of Fire.
Hurricanes—called typhoons or cyclones in the Pacific—are Earth’s biggest storms. When conditions are right, they form over the ocean from collections of storms and clouds known as tropical disturbances. Strong winds create a wall of clouds and rain that swirl in a circle around a calm center called the eye. If wind speeds reach 39 mph, the storm is named. If wind speeds top 74 mph, the storm is called a hurricane. Hurricanes are classified into five categories depending on their wind speeds.
Hurricanes can be hundreds of miles wide. On land, the storm can snap trees and tear buildings apart. Strong winds blowing toward shore can create a rise in the ocean water called a storm surge. It can combine with heavy rains to cause flooding and massive damage.
For the Atlantic Ocean, Caribbean Sea, and Gulf of Mexico, hurricane season runs from June 1 to November 30.
Categories
The U.S. began using women’s names for hurricanes in 1953 and added men’s names in 1979. When all letters (except Q, U, X, Y, and Z) are used in one season, any additional storms are named with Greek letters.
Hurricane Names
Sandy was the second-most-destructive tropical storm ever to hit the United States. It made landfall (came onshore) in southern
New Jersey on the evening of October 29, 2012. Besides bringing high winds and heavy rain, it caused a huge storm surge. Walls of water, some more than 9 feet tall, hit coastal areas in New Jersey; New York City; Long Island, NY; and southern New England. Hundreds of thousands of buildings were destroyed or severely damaged.
HURRICANESS
Date Location What Happened? Deaths
(estimated)
Sept. 8, 1900 Galveston, TX Category 4 storm flooded the island with 15-foot waves. 8,000+
Sept. 16-17, 1928
Central/southern FL
Category 5 storm, the fourth-largest to hit the U.S. mainland, caused 9-foot waves.
1,836
Sept. 21, 1938
NY, CT, RI, MA “The Long Island Express,” with storm surges rising 10-25 feet, caused $306 million in damages.
682
Aug. 25-29, 2005
LA, MS, AL, GA, FL
Hurricane Katrina, with 175 mph winds and a 25-foot high storm surge, caused about $125 billion in damage.
1,833+
Oct. 29-30, 2012
NY, NJ, other eastern states
Sandy, a huge storm measuring 1,000 miles wide, caused at least $50 billion in damage.
Tornadoes, or twisters, are rapidly spinning columns of air. They usually form when winds change direction, speed up, and spin around in or near a thunderstorm.
Tornadoes can happen any time that the weather is right, but they are more common between March and July. They can happen in any state, but strong tornadoes often touch down in the U.S. Midwest and Southeast. A group of states including Texas, Oklahoma, Kansas, Nebraska, Iowa, and South Dakota is sometimes called Tornado Alley because of the large number of twisters that occur in the region.
According to the National Oceanic and Atmospheric Administration (NOAA), about 1,000 tornadoes occur in the U.S. each year.
Tornadoes are measured by how much damage they cause. In February 2007, the U.S.
WEAKEF0: 65-85 mphEF1: 86-110 mph
STRONG
EF2: 111-135 mphEF3: 136-165 mph
VIOLENTEF4: 166-200 mphEF5: over 200 mph
(since record keeping began in 1950)
YEARYEAR: The 1,817 tornadoes reported in 2004 topped the previous record of 1,424 in 1998.
MONTH:MONTH: In April 2011, there were a total of 758 tornadoes, easily passing the old record of 542 set in May 2003.
SINGLE EVENT:SINGLE EVENT: On April 25-28, 2011, an estimated 305 tornadoes touched down in Alabama and a number of other states, mostly in the Southeast, causing more than 300 deaths.
Most tornadoes and the storm clouds that create them are very dark gray. But some tornadoes look red. These red tornadoes are most common in parts of Oklahoma and Kansas that have reddish soil. The swirling winds inside a tornado pick up enough dust to turn the twister red.
Tornadoes, or twisters, are rapidly spinning columns of air. They rapidsters, are ra y sp ng c umns ofare ly spinor nad
began using the Enhanced Fujita (EF) Scale to measure tornadoes. The EF-Scale provides an estimate of a tornado’s wind speed based on the amount of damage. If a tornado doesn’t hit anything, it may be hard to classify it.
Wind speeds are difficult to measure directly, because measuring instruments can be destroyed in more violent winds. The highest speed ever recorded—302 mph—was taken in May 1999 in an Oklahoma tornado. A huge EF5 tornado hit the same area, in and around Moore, OK, in May 2013.