Earthquakes!

what causes the earth/ground to shake?

Earth quake

An earthquake (also known as a quake, tremor or temblor) is the result of a sudden release of energy in the Earths crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time.

How Do Earthquakes Start?

Earthquakes are a sudden release of energy in the Earth's crust. Earthquakes most commonly occur at the boundaries of tectonic plates where stresses accumulate in the earth's crust over time, causing energy to be stored in the form of elastic strain (like that in a compressed spring). Ultimately this stress will exceed the shear strength of the crust in the fault or boundary zone causing a sudden brittle failure or rupture. This in turn causes movement and a sudden release of the stored elastic strain energy in the form of seismic waves (as well as heat) causing an earthquake.

Earthquake Facts:

The largest recorded earthquake in the United States was a magnitude 9.2 that struck Prince William Sound, Alaska on Good Friday, March 28, 1964 UTC. The largest recorded earthquake in the world was a magnitude 9.5 (Mw) in Chile on May 22, 1960. The earliest reported earthquake in California was felt in 1769 by the exploring expedition of Gaspar de Portola while the group was camping about 48 kilometers (30 miles) southeast of Los Angeles. Before electronics allowed recordings of large earthquakes, scientists built large spring-pendulum seismometers in an attempt to record the long-period motion produced by such quakes. The largest one weighed about 15 tons. There is a medium-sized one three stories high in Mexico City that is still in operation. The average rate of motion across the San Andreas Fault Zone during the past 3 million years is 56 mm/yr (2 in/yr). This is about the same rate at which your fingernails grow. Assuming this rate continues, scientists project that Los Angeles and San Francisco will be adjacent to one another in approximately 15 million years.

About Earth and Earth quakes

How to prepare for an earthquake!!

The Japan earthquake...

Why was Japan's March 11 earthquake so big? One answer is the large size of the fault rupture as well as the speed at which the Pacific Plate is continuously thrusting beneath Japan, U.S. Geological Survey (U.S.G.S.) scientist Tom Brocher told KQED News. People felt shaking in cities all over Honshu, Japan's main island.Below are some more facts and figures relating to the causes and consequences of the world's fifth-largest earthquake since 1900. Magnitude, according to USGS: 9.0Speed at which the Pacific Plate is smashing into the Japanese island arc: 8.9 centimeters (3.5 inches) per yearSpeed at which the San Andreas Fault in California is slipping: about 4 centimeters per yearSize of the rupture along the boundary between the Pacific and North American plates: 290 kilometers (180 miles) long, 80 kilometers acrossApproximate length of Honshu island: 1,300 kilometersYears since an earthquake of this magnitude has hit the plate boundary of Japan: 1,200 Duration of strong shaking reported from Japan: three to five minutes Greatest distance from epicenter that visitors to the USGS Web site reported feeling the quake: About 2,000 kilometers

The fouth largest earthquake...was in Japan March 11,2011

At least 15,703 people killed, 4,647 missing, 5,314 injured, 130,927 displaced and at least 332,395 buildings, 2,126 roads, 56 bridges and 26 railways destroyed or damaged by the earthquake and tsunami along the entire east coast of Honshu from Chiba to Aomori. The majority of casualties and damage occurred in Iwate, Miyagi and Fukushima from a Pacific-wide tsunami with a maximum runup height of 37.88 m at Miyako. The total economic loss in Japan was estimated at 309 billion US dollars. Electricity, gas and water supplies, telecommunications and railway service disrupted and several reactors severely damaged at a nuclear power plant near Okuma. Several fires occurred in Chiba and Miyagi. At least 1,800 houses destroyed when a dam failed in Fukushima. Maximum acceleration of 2.93 g recorded at Tsukidate. Horizontal displacement and subsidence observed. Landslides occurred in Miyagi. Liquefaction observed at Chiba, Odaiba, Tokyo and Urayasu. The tsunami destroyed or severely damaged many coastal towns in the Kuji-Minamisanriku-Nami area. One person killed and several houses destroyed at Jayapura, Indonesia by a tsunami with a wave height of 2 m. One person killed south of Crescent City, California and several boats and docks destroyed or damaged at Crescent City by a tsunami with a recorded wave height of 247 cm. Several houses, boats and docks destroyed or damaged at Santa Cruz, California; Brookings, Oregon; Hale`iwa, Kailua Kona and Kealakekua, Hawaii. Some buildings damaged slightly in the Galapagos Islands, Ecuador by a tsunami with a recorded wave height of 208 cm at Santa Cruz. Several houses destroyed at Pisco, Peru. Several buildings destroyed at Dichato and several boats damaged at Puerto Viejo and on Isla Chiloe, Chile. Felt (VIII) at Fukushima, (VII) at Agui, Hiratsuka, Kiryu, Komae, Oyama, Sendai and Tsukuba and (VI) in much of eastern Honshu, including the Tokyo-Yokohama area, Japan. Felt from Hokkaido to Kyushu. Recorded (7 JMA) in Miyagi. Felt in Northern Mariana Islands, North Korea, South Korea, Taiwan, northeastern China and southeastern Russia as far as Kaohsiung, Beijing and Petropavlovsk-Kamchatskiy. Seiches observed at Leikanger, Norway. Water fluctuations observed in a well in Newfoundland, Canada. The tsunami had maximum runup heights of 29.6 m at Ofunato, 18.4 m at Onagawa and 9.4 m at Iwaki. To watch a video about the 4th largest earthquake go to this website  http://www.schooltube.com/video/cb98ce9d2fc833df9c68/Japan%20Earthquake%20March%2011,%202011

World's Largest Recorded Earthquake!

The Great Chilean Earthquake

The Great Chilean EarthquakeThe World’s largest earthquake with a instrumentally documented magnitude occurred on May 22, 1960 near Valdivia, in southern Chile. It has been assigned a magnitude of 9.5 by the United States Geological Survey. It is referred to as the "Great Chilean Earthquake" and the "1960 Valdivia Earthquake. The United States Geological Survey reports this event as the "largest earthquake of the 20th Century". Other earthquakes in recorded history may have been larger, however this is the largest earthquake that has occurred since accurate estimates of magnitude became possible in the earnly 1900's. The World’s largest earthquake with a instrumentally documented magnitude occurred on May 22, 1960 near Valdivia, in southern Chile. It has been assigned a magnitude of 9.5 by the United States Geological Survey. It is referred to as the "Great Chilean Earthquake" and the "1960 Valdivia Earthquake. The United States Geological Survey reports this event as the "largest earthquake of the 20th Century". Other earthquakes in recorded history may have been larger, however this is the largest earthquake that has occurred since accurate estimates of magnitude became possible in the earnly 1900's.

Resources used:

www.wikipedia.com    www.schooltube.com    www.techertube.com   www.cbsnews.com

By: Haley Spicer and Lakota Fulton!!