Chapter4_post - Chapter 4 outline Forecasting EQs and...

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Chapter 4 outline – Forecasting EQs and Mitigating EQ Damage Earthquake prediction: where and when will fault slip? One successful earthquake prediction (there were precursor events) : Haicheng Precursor events that help determine where and when fault may slip Prediction consequences Earthquake Early Warning systems Forecasting EQs: a) where will fault slip, b) what is the frequency and c) probable magnitude? Methods of forecasting EQs First establish pattern of movement on fault Then look for seismic gaps or EQ migration Examples Seismic Hazard Maps Minimizing EQ damage Structural design: diagonal supports, reinforced steel bracing, foundation bolts, adequate building spacing, no weak floors, wooden/steel frames, base isolation Land use planning EQ preparedness
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Predicting Earthquakes Earthquake prediction involves estimating specifically when and where an earthquake is likely to occur. At this point, scientists cannot predict date and time when earthquake will strike, but do understand which regions are likely to experience earthquakes. Hence, the primary objective is to provide reasonably reliable warning of impending earthquake (e.g. in terms of probability).
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Predicted Earthquake Arrives on Schedule Early afternoon February 4, 1975: officials in Haicheng, China issued warning to expect large earthquake in next two days, asked people to remain outside 7:36 pm (same day): magnitude 7.3 earthquake struck 90% of buildings damaged or destroyed 2,014 deaths, 27,500 injuries, out of 3 million people Were it not for the prediction, the death toll would have been significantly higher. Notice posted outside a cinema – “due to the impending earthquake, the movie will be shown outdoor”
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Predicted Earthquake Arrives on Schedule The Haicheng earthquake prediction was based on Increase in small earthquakes (enhanced foreshock activity) Rise in elevation, ground tilting near fault Changes in groundwater levels, magnetic field Strange animal behavior
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The Great Tangshan Earthquake Magnitude 7.6 earthquake struck Tangshan (city with population of 1 million) was devastated unlike Haicheng, this earthquake was not predicted
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This note was uploaded on 02/02/2010 for the course GEO 107 taught by Professor Stidham during the Fall '08 term at SUNY Stony Brook.

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Chapter4_post - Chapter 4 outline Forecasting EQs and...

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