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Need: “music” CD of eq sounds Stick to break Slinky Smithsonian CD THE STORY OF AN EYEWITNESS By Jack London, Collier's special Correspondent (First published in Collier's, May 5, 1906) http://london.sonoma.edu/Writings/Journalism/sfearthquake.html http://www.youtube.com/watch?v=4Xebwzb3dDE Japan, subduction zone earthquake RECORDS OF EARTHQUAKE WAVES Three sets of waves recorded for each EQ, P, S, and surface waves. TIME-DISTANCE GRAPHS LOCATING EARTHQUAKES Seismic Wave Propagation M9.0_Earthquake_Japan 110308.mov http://www.youtube.com/watch?v=R8dsrBf16pc INTERPRETING EARTHQUAKES WORLDWIDE STANDARD SEISMOGRAPH NETWORK EARTHQUAKE INTENSITY EQ effects classified in terms degrees of intensity. Modified by Mercalli in 1902 12 degrees of intensity. Michigan’s Largest Earthquake 1947 Intensity VI M=4,6 VI. Felt by all, many frightened. Some heavy furniture moved; a few instances of fallen plaster. Damage slight. Magnitude 9.0 NEAR THE EAST COAST OF HONSHU, JAPAN Friday, March 11, 2011 at 05:46:23 UTC Shaking intensity scales were developed to standardize the measurements and ease comparison of different earthquakes. The Modified-Mercalli Intensity scale is a twelve-stage scale, numbered from I to XII. The lower numbers represent imperceptible shaking levels, XII represents total destruction. A value of IV indicates a level of shaking that is felt by most people. Modified Mercalli Intensity Perceived Shaking Extreme Violent Severe Very Strong Strong Moderate Light Weak Not Felt Image courtesy of the US Geological Survey USGS Estimated shaking Intensity from M 9.0 Earthquake Magnitude - an index to the energy released by an EQ as reflected by the amplitude of seismic waves. Ex: M 2.5, felt by most people in vicinity M 4.5, some damage M 6, potentially destructive >M 7, major EQ Note: scale is logarithmic. Ex: M6 to M8 = 100 times as large amplitude Note: An increase in one magnitude equals a 40 times increase in released energy. Ex: M6 to M8 = 1,600 times more energy released. Magnitude 9.0 NEAR THE EAST COAST OF HONSHU, JAPAN Friday, March 11, 2011 at 05:46:23 UTC Globally, this is the 4th largest earthquake since 1900. Great (M > 8) Earthquakes Since 1900 9.6 Chile 1960 9.4 Alaska 1964 9.2 Magnitude Sumatra 2004 Russia 1952 9 8.8 Japan 2011 Ecuador 1906 Chile 2010 Alaska 1965 8.6 8.4 8.2 8 7.8 1900 1920 1940 1960 Year 1980 2000 2020 Magnitude 9.0 NEAR THE EAST COAST OF HONSHU, JAPAN Friday, March 11, 2011 at 05:46:23 UTC The moment magnitude scale is designed to give an accurate characterization of the true size of an earthquake, but be tied to the original description of magnitude that was developed by Charles Richter. Moment magnitude accounts for earthquake size by looking at all the energy released. It is striking that only 6 earthquakes over the last 106 years account for over half of the energy released during that time. New Mexico Institute of Mining and Technology Magnitude 7.0 HAITI Tuesday, January 12, 2010 at 21:53:09 UTC The earthquake occurred about 10 miles west of the capital of Haiti, Port-au-Prince, and caused extreme shaking. USGS Shaking Intensity Mike Blanpied of the US Geological Survey said that, based on the location and size of the quake, about three million people would have been severely shaken by its impact. Modified Mercalli Intensity Perceived Shaking Extreme Violent Severe Very Strong Strong Moderate Light Weak Not Felt Lower magnitude EQs can be more hazardous if in populated areas or in areas of poor construction. 1. Most EQs in circum-pacific, area of active volcanism (80% of energy). 2. Burma, Himalayas, Iran, Europe (15% of energy). 3. MORs and the other locations. Number of Earthquakes 1974-2003 1. Alaska 57.2 % 2. California 23.2 % 3. Hawaii 7.3 % 4. Nevada 3.7 % 5. Washington 2.0 % 6. Idaho 1.9 % 7. Wyoming 1.0 % 8. Montana 0.9 % 9. Utah 0.7 % 10. Oregon 0.3 % Magnitude 9.0 NEAR THE EAST COAST OF HONSHU, JAPAN Friday, March 11, 2011 at 05:46:23 UTC The map on the right shows historic earthquake activity near the epicenter (star) from 1990 to present. As shown on the cross section, earthquakes are shallow (orange dots) at the Japan Trench and increase to 300 km depth (blue dots) towards the west as the Pacific Plate dives deeper beneath Japan. Seismicity Cross Section across the subduction zone showing the relationship between color and earthquake depth. Images courtesy of the US Geological Survey Draw layers of the Earth Layers of the Earth Chemical = crust, mantle, core Physical = lithosphere, asthenosphere, lower mantle, outer core, and inner core STRUCTURE OF THE EARTH A.CRUST Base of the crust, the Moho, first detected in 1909. Crust of the Continents Thickness varies: greater in mountains than lowlands. Crust Under Oceans Average about 5km. Mafic, rich in magnesium and iron (basalt). B. MANTLE Mantle extends down to 2,900 km. Both P and S-waves travel through. Must be solid. C. LITHOSPHERE AND ASTHENOSPHERE Lithosphere - rigid crust and uppermost mantle Asthenosphere - plastic mantle Top of the asthenosphere has a low-velocity zone, where body waves decrease in velocity. Rocks close to their melting temperature, less elastic, and more plastic. Less efficient at transmitting wave. D. CORE Extends from 2,900 km to center of the Earth at a depth of 6,370 km. No S-waves observed from 103-142 degrees from the source S-wave seismic shadow. Interpretation: liquid outer core. Size determined by size of shadow. P-waves reflect off of denser layer within the core. Interpretation: solid inner core of same composition. EFFECTS OF EARTHQUAKES A. FIRE B. DAMAGE TO STRUCTURES C. SEISMIC SEA WAVES (Tsunami) D. LANDSLIDES E. LIQUEFACTION Japan earthquake: Footage of moment tsunami hit http://www.bbc.co.uk/news/world-asia-pacific-12725646 Tsunami Fire Kobe 1995 Damage to Structures Kobe 1995 Northridge, 1994 Tsunami Making Waves, Saving Lives http://www.youtube.com/watch?v=ZXxDUkGMNLs&feature=autoplay&list=PL01AC183B464BAC05&index=29&playnext=2 Landslide