earthquakes.ppt

* * * * * * Replace with a new original * * * b Satellite image of the north shore of Banda Aceh, the capital city of Aceh Provence, Sumatra, Indonesia, taken on June 23, 2004. * * * * * * * * * * * * * * * * * * Earthquake Prediction Seismic risk maps help geologists in determining the likelihood and potential severity of future earthquakes based on the intensity of past earthquakes. Fig. 8.18, p. 209 Earthquake Prediction Earthquake Precursors – short-term and long-term changes within the Earth prior to an earthquake that assist in prediction. Seismic gaps – locked portions of the fault where pressure is building Surface elevation changes and tilting Ground water table fluctuations Anomalous animal behavior Fig. 8.19, p. 210 Earthquake Prediction Earthquake Prediction Programs Earthquake prediction research programs are being conducted in the United States, Russia, China, and Japan. Research involves laboratory and field studies of rock behavior before, during, and after large earthquakes, as well as monitoring major active faults. Related studies, unfortunately, indicate that most people would probably not heed a short-term earthquake warning. Earthquake Prediction Earthquake Preparation Table 8.5, p. 211 Earthquake Control Because of the tremendous energy involved, it seems unlikely that humans will ever be able to prevent earthquakes. However, it might be possible to release small amounts of the energy stored in rocks and thus avoid a large earthquake and the extensive damage that typically results. One promising means of earthquake control is by fluid injection along locked segments of an active fault. Fig. 8.20, p. 212 What is Earth’s Interior Like? The concentric layers of Earth, from its surface to interior, are : Oceanic / Continental crust Rocky mantle Iron-rich core liquid outer core solid inner core Fig. 8.21, p. 214 What is Earth’s Interior Like? Geologist study the bending or refraction and reflection of P- and S-waves to help understa