Transcript Earthquakes
Earthquakes in the U.S. By: Allison Kantner and Nikki Ryan Prince William Sound, Alaska • • • • • March 28, 1964 Magnitude: 9.2: Second largest ever Lasted four minutes Aftershock zone was about 250 km wide and extended 800 km • Thousands of aftershocks were recorded • Caused by the compression of the crust by the nw motion of the Pacific Plate Andreanof Islands, Alaska March 9, 1957 – Magnitude 9.1 – Third largest earthquake in the 20th Century – Destroyed two bridges, damaged houses, and left a 4.5 meter crack in the road. – Mount Vsevidof erupted after being dormant for 200 years. – Shock generated a 15 meter tsunami that continued to Hawaii. Gulf of Alaska • Damage consisted of broken glassware and cracks in plaster, drywall, windows, and foundation • Magnitude 7.9 • Depth is 65 km • Light damage occurred • in other towns • Strong building vibrations • made it difficult to stand or walk Denali Fault, Alaska • November 3, 2002 •Magnitude 7.9 •Largest inland earthquake in North America in almost 150 years •Total rupture length: about 330 km •Rupture lasted 100 seconds from its initiation to its arrest •Multiple land slides and rock avalanches resulted •Earthquake was felt in Washington and caused seiches in pools and lakes as far as Texas and Louisiana Gorda Plate • November 8, 1980 • Magnitude: 7.4 • Caused minimal damage considering the magnitude • Center of the shock located offshore Kern County, California July 21, 1952 – Magnitude 7.3 – 12 deaths – Caused property damage worth $60 million – Cracked reinforced-concrete tunnels with 46 cm thick walls – Bear Mountain moved upward and to the north – A building in Las Vegas required realignment of the structural steel – Felt over most of California and in the western parts of Arizona and Nevada Hebgen Lake, Montana • August 18, 1959 • Magnitude: 7.3 • Caused 28 fatalities,$11 million dollars damage to highways and forests • Most disastrous effect: huge avalanche cascading down the Madison river Canyon • This stopped the flow of the Madison river and within weeks created a lake 53 m deep Landers, California June 28, 1992 – Magnitude 7.3 – More than 400 people were injured – Preliminary estimate of damage (combined with a 6.7 event earlier that day): $92 million – Felt throughout southern California, southern Nevada, western Arizona, and southern Utah – Felt in high-rise buildings as far north as Boise, Idaho, and as far east as Albuquerque, New Mexico, and Denver. – Seiches reported in Lake Union, Washington, Aurora, Colorado, and Corpus Christi, Texas Kalapana, Hawaii • • • • • • Nov. 29, 1975 Magnitude: 7.2 Killed 2 people and injured several Inflicted property damage at $4.1 million Hundreds of aftershocks felt Felt throughout Hawaii Island and on Lanai, Molokai, and Oahu. • Caused a brief, sudden volcanic eruption Borah Peak, Idaho • October 28, 1983 – – – – – Magnitude 7.0 Largest earthquake recorded in Idaho 2 deaths $12.5 million in property damage Ground breakage was as wide as 100 meters – Rockfalls and landslides on the Lost River Range – Felt in parts of Montana, Nevada, Oregon, Utah, Washington, Wyoming, and in the Provinces of Alberta, British Columbia, and Saskatchewan, Canada Dixie Valley, Nevada • December 16, 1954 • Magnitude: 7.1 • Minor geologic effects included changes in the flow of springs and wells, formation of craters and water fountains, landslips and landslides, mudflows, and rock falls. • The earthquake was accompanied by offsets along many faults in the four main zones of a north-trending belt 96 kilometers long by 32 kilometers wide. What Causes Earthquakes? Rock underground suddenly breaks along a fault This causes seismic waves The two blocks of rock, or faults, push against each other Due to all of the pressure, the rocks break. This causes the earthquake to occur. Earthquake Facts There are 19 major (magnitude larger than 7) earthquakes every year Earthquakes tend to be concentrated in narrow zones There are 7 major crustal plates on earth that move from less than .5 to 5 inches per year There are several million earthquakes in the world each year The largest earthquake recorded took place in Chile in 1960. It had a magnitude of 9.5 Questions How far did the tsunami that was generated by the Andreanof Island earthquake of 1957 continue? Which earthquake was the largest inland earthquake in almost 150 years? How many major earthquakes are there every year? What causes earthquakes? How many major crustal plates are there on earth? Bibliography http://neic.usgs.gov/neis/eq_depot/usa/1957_03_09.html http://www.dot.state.ak.us/comm/denali_quake/pages/IMG_0 128.htm : Denali Fault, Alaska http://www.giseis.alaska.edu/Seis/M7.9_quake_2002/M7.9_q uake.html http://neic.usgs.gov/neis/eq_depot/usa/1952_07_21.html http://neic.usgs.gov/neis/eq_depot/usa/1992_06_28.html http://wwwneic.cr.usgs.gov/neis/eq_depot/usa/1983_10_28.ht ml