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Unformatted text preview: 1755- The Great Lisbon Earthquake (Portugal)3 typical components:-quakes or shaking-tsunami or tidal wave-fires-more than 60,000 people diedJohn Winthrop (1755)-an astronomer at Harvard who suggested that earth are waves within the earth based on the observation of moving bricks in his chimney during the Boston earthquake in 1755John Mitchell (1760)-an astronomer at Cambridge who attributed earthquakes to waves cause by shifting rocks deep within the earth (movement cause by fire and steam). -made a method to calculate the location (epicenter) of an earthquake Robert Mallet (1857)-an Irish engineer -mapped earthquake zones around the Mediterranean-produced contour maps of equal devastation- suggested that earthquakes are elastic waves of compression caused by the sudden flexing or fracturing of the earths crust. John Milne (1891)-an English geologist considered to be the founder of modern earthquake studies and the science of seismology. Noted 3 types of earthquake motions:-back and forth waves---------P waves-up and down waves----------S waves-side to side waves------------L wavesEpicenter-time interval between the first set of waves and later waves (every second is 5 miles)Guissepi Mercalli (1902)-devised an intensity scale (1-12) based on:--impressions of people involved--movement of objects--damage to buildingsCauses of Earthquakes:-tectonic-volcanic-collapseTectonic Earthquakes:-most occur at plate margins...
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- Spring '08