105_08-quakes_part_3 - Damages Gleebruk Village, Banda...

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Unformatted text preview: Damages Gleebruk Village, Banda Aceh, Indonesia - After Damages Damages Phuket, Thailand Phuket Damages Phuket, Thailand Damages Damages Phuket, Thailand Damages Damages Phuket, Thailand Damages Damages Phuket, Thailand 1 Damages Phuket, Thailand Damages Damages Phuket, Thailand Damages Damages Phuket, Thailand Damages Damages Phuket, Thailand Damages Damages Phuket, Thailand Damages Damages Phuket, Thailand 2 Damages Phuket, Thailand Damages Damages Phuket, Thailand Damages Damages Phuket, Thailand Damages Damages Phuket, Thailand Minimize Minimize the Effects of Earthquakes Building Building codes: – San Francisco quake in 1986 with a Richter magnitude of 7.1 killed 40 – 10 months later a quake in Armenia (no earthquake proof building code) with a magnitude of 6.9 killed 25,000! 3 Minimize the Effects of Earthquakes Earthquake prediction of foreshocks • establishing network of seismographs • landform studies (uplift, subsidence, or movement movement along faults • animal behavior • monitoring Earthquake prediction Location? Location? For the most part Magnitude? Magnitude? For the most part Time? Time? No! Years or decades maybe LongLong-term predictions? Yes, useful for establishing building codes Can Earthquakes be Predicted? – produce risk assessments The Earth’s Interior Crust, Crust, mantle, core 4 The Earth’s Interior How How do we know? The Earth’s Interior How How do we know? The Earth’s Interior How How do we know? Seismic waves Not Not only dangerous, but also useful for: – Mapping the Earth’s interior – Exploration of resources Geophysics – Branch of geology – Application of physics to the study of the Earth – Studies: Seismic Seismic waves Earth’s Earth’s magnetic field Gravity Gravity Heat Heat Seismic waves Seismic waves Reflection: Reflection: – Waves are reflected from interface between two different materials Refraction: – Waves are bent as they pass through different material (density, rigidity) Waves bend toward the layer of lower velocity 5 Seismic waves Earth’s Interior Crust Crust Mantle Mantle Core Core Earth’s Interior Earth’s Interior Crust Crust – Thin layer of solid rock covering the Earth’s surface Oceanic Oceanic crust – Thinner – More dense (higher velocity) Continental Continental crust – Thicker – Less dense (lower velocity) Moho Moho – Mohorovičić discontinuity – Boundary between crust & mantle Earth’s Interior Mantle Mantle – Solid, perhaps with some small pockets of magma in upper mantle Earth’s Interior Mantle Mantle – Asthenosphere Low Low velocity zone Rocks Rocks closer to their melting point, possibly partially melted Lithosphere Lithosphere – Made of the crust and upper mantle – Makes up plates from plate tectonic theory – Partial melting May May generate magma May May allow rocks to flow, which can drive plate tectonics 6 P Wave Shadow Zone 0º Epicenter P Wave Shadow Zone No P-waves are Preceived in a zone between 103o and and 142o away from the away epicenter. 103º 103º 142º 142º 180º Shadow zone S Wave Shadow Zone 0º Epicenter S Wave Shadow Zone S waves do not travel through liquids: Liquid outer core! No S-waves are Sreceived beyond 103o away from the away epicenter. 103º 103º Shadow Zone 180º The Core Seismic Exploration for Petroleum Uses Uses artificial sources of seismic energy, such as dynamite. Composition Composition of the Core – behavior of P and S waves indicates a liquid outer core, with possibly a solid inner core – core is iron mixed with nickel and possibly other lighter elements 7 Laying Laying out seismic equipment Triggering the explosives Explosion! 8 Earthquakes & Earth’s Interior Chapter 8 9 ...
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