Lecture 21 (November 13)

Lecture 21 (November 13) - Affected 10-story buildings •...

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Sedimentary Basins o Weak sand and gravel resonate and amplify seismic energy o Seismic energy is trapped in the basin and amplified o Ground Shaking Much stronger Amplitude of ground motions can be as much as 10x greater than bedrock sites the same distance from eq Much longer Duration can be as much as 4x longer than bedrock sites the same distance from eq o L.A. Basin 10km deep o Basin-Edge Effects There’s damage along edge of sedimentary basins 1985 Mexico City M W 8.1 Eq o 1-2 sec energy preferentially resonated and amplified in old lake clay deposits
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Unformatted text preview: Affected 10-story buildings • 2/3 of the buildings damaged were between 6-15 stories • Liquefaction (of soil) o Process of soil and sand behaving like a dense fluid rather than a wet solid mass during an eq Pressurizing the interstitial fluid will cause liquefaction to happen o 1964 Niigata, Japan Eq Many buildings collapsed because of liquefaction in sandy soil foundation...
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This note was uploaded on 01/27/2009 for the course GEOL 240Lxg taught by Professor 12:30-01:50pm during the Fall '07 term at USC.

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