Earthquakes An earthquake is a sudden rapid shaking of the earth. They are caused by the breaking and shifting of the rock beneath the earth’s surface. Often found in conjunction with Plate tectonic boundaries.

An earthquake can cause: -buildings and bridges to collapse -disrupt utility supply lines -trigger landslides, avalanches, flash floods, fires, and huge destructive ocean waves.

Earthquakes Earthquakes

Residence in Los Gatos moved off its foundation

Hector Mine surface rupture

Earthquake Location Map Ninety percent of the world's earthquakes occur in specific areas that are the boundaries of the Earth's major crustal plates. Shown on the map are the epicenter locations of earthquakes of magnitude 4.5 or greater that occurred from 1978 through 1987.

Ring of Fire The "Ring of Fire", also called the Circum-Pacific belt, is the zone of earthquakes surrounding the Pacific Ocean--about 90% of the world's earthquakes occur there.

Plate Boundary Types Convergent Boundaries Divergent Boundaries Transform Faults

Convergent Boundary Mountain Building

Convergent Boundary Subduction Zone

Divergent Boundary Sea Floor Spreading

Transform Fault Plates move past each other.

Most Recent Utah Earthquake July 11, 2003 – Near Huntsville

Seismicity of the U.S

Earthquake Measurements Magnitude – Richter Scale Energy released during the earthquake Intensity – Mercalli Scale Damage or loss of life caused by the earthquake

Richter Scale The Richter magnitudes are based on a logarithmic scale (base 10). What this means is that for each whole number you go up on the Richter scale, the amplitude of the ground motion recorded by a seismograph goes up ten times. Invented by Charles F. Richter in 1934

Richter Scale Measurement Richter Scale is calculated using a seismograph

Seismometer A seismograph, or seismometer, is an instrument used to detect and record earthquakes. Generally, it consists of a mass attached to a fixed base. During an earthquake, the base moves and the mass does not.

Locating Earthquakes

Richter Scale Often felt, but rarely causes damage. Under 6.0 At most slight damage to well-designed buildings. Can cause major damage to poorly constructed buildings over small regions Can be destructive in areas up to about 100 kilometers across where people live Major earthquake. Can cause serious damage over larger areas. 8 or greater Great earthquake. Can cause serious damage in areas several hundred kilometers across.

Mercalli scale Invented by Giuseppe Mercalli in 1902, This scale uses the observations of the people who experienced the earthquake to estimate its intensity.

Mercalli Scale I. Not felt except by a very few under especially favorable circumstances. II. Felt only by a few persons at rest, especially on upper floors of buildings. Delicately suspended objects may swing. III. Felt quite noticeably indoors, especially on upper floors of buildings, but many people do not recognize it as an earthquake. Standing automobiles may rock slightly. Vibration like passing of truck. Duration estimated. IV. During the day felt indoors by many, outdoors by few. At night some awakened. Dishes, windows, doors disturbed; walls make creaking sound. Sensation like heavy truck striking building. Standing automobiles rocked noticeably.

Mercalli Scale Cont. V. Felt by nearly everyone, many awakened. Some dishes, windows, and so on broken; cracked plaster in a few places; unstable objects overturned. Disturbances of trees, poles, and other tall objects sometimes noticed. Pendulum clocks may stop. VI. Felt by all, many frightened and run outdoors. Some heavy furniture moved; a few instances of fallen plaster and damaged chimneys. Damage slight. VII. Everybody runs outdoors. Damage negligible in buildings of good design and construction; slight to moderate in well built ordinary structures; considerable in poorly built or badly designed structures; some chimneys broken. Noticed by persons driving cars. VIII. Damage slight in specially designed structures; considerable in ordinary substantial buildings with partial collapse; great in poorly built structures. Panel walls thrown out of frame structures. Fall of chimneys, factory stack, columns, monuments, walls.Heavy furniture overturned. Sand and mud ejected in small amounts. Changes in well water. Persons driving cars disturbed.

Mercalli Scale Cont. IX. Damage considerable in specially designed structures; well designed frame structures thrown out of plumb; great in substantial buildings, with partial collapse. Buildings shifted off foundations. Ground cracked conspicuously. Underground pipes broken. X. Some well built wooden structures destroyed; most masonry and frame structures destroyed with foundations; ground badly cracked. Rails bent. Landslides considerable from river banks and steep slopes. Shifted sand and mud. Water splashed, slopped over banks. XI. Few, if any, (masonry) structures remain standing. Bridges destroyed. Broad fissures in ground. Underground pipelines completely out of service Earth slumps and land slips in soft ground. Rails bent greatly. XII. Damage total. Waves seen on ground surface. Lines of sight and level distorted. Objects thrown into the air.

Earthquake Terminology Epicenter – area on the earths surface directly above the focus or hypocenter Fault – area of two surfaces of rock move passed one another Focus – actual location of the earthquake Hypocenter – same as the focus

Types of Earthquake Waves Primary or P waves Secondary or S waves Surface or L waves

Body waves

Surface waves

Tsunami Tsunami Tsunamigenic is referring to those earthquakes, commonly along major subduction- zone plate boundaries such as those bordering the Pacific Ocean, that can generate tsunamis.subduction- zone

Destructive Earthquakes Date Location Deaths Mag Comments January 23, 1556 China, Shansi 830,000 July 27, 1976 China, Tangshan 255,000* 8.0 Estimated death toll (official) as high as 655,000. August 9, 1138 Syria, Aleppo 230,000 May 22, 1927 China, near Xining 200, Large fractures. December 22, 856+ Iran, Damghan 200,000 December 16, 1920 China, Gansu 200, Major fractures, landslides. March 23, 893+ Iran, Ardabil 150,000 September 1, 1923 Japan, Kwanto 143, Great Tokyo fire. October 5, 1948 USSR 110, (Turkmenistan, Ashgabat) December 28, 1908 Italy, Messina 70, Deaths from 100,000 earthquake and (estimated) tsunami.

Annual Earthquakes Magnitude Average Annually Great 8 and higher 1 Major 7 _ Strong 6 _ Moderate 5 _ Light 4 _ 4.9 6,200 (estimated) Minor 3 _ ,000 (estimated) Very Minor 2 _ 3: about 1,000 per day 1 _ 2: about 8,000 per day

Earthquakes 1900's 1. Chile Mw 2. Prince William Sound, Alaska Mw 3. Andrean of Islands, Aleutian Islands Mw 4. Kamchatka Mw 5. Off the Coast of Ecuador Mw 6. Rat Islands, Aleutian Islands Mw 7. India_China Border Mw 8. Kamchatka Mw 9. Banda Sea, Indonesia Mw 10. Kuril Islands Mw

Remember It’s not “ If ” But When!!!!!!!

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