11.4 The following shows ground motion recordings from two adjoining islands in the San Francisco Bay during the 1979 Loma Prieta earthquake. Treasure Island and Yerba Buena Island are both located at a distance of about 50 miles from the epicenter. Treasure Island was created in the 1930s by filling sand over underwater bay mud deposits, while Yerba Buena Island is a natural rock outcrop. The recordings showed a significant difference in amplification between the two adjacent sites. a Acceleration- 0.1 0.0 -0.1 0.1 0.0 -0.1 0 0 5 a) Which island has a soft soil condition? 10 10 15 15 Time-seconds 20 20 25 25 30 c) What was the approximate ratio of the peak ground acceleration at these sites? 30 b) Which recording was from Treasure Island and which one was from Yerba Buena Island? In other words, which site, soft soil or stiff rock, produced the larger shaking?

11.4 The following shows ground motion recordings from two adjoining islands in the San Francisco Bay during the 1979 Loma Prieta earthquake. Treasure Island and Yerba Buena Island are both located at a distance of about 50 miles from the epicenter. Treasure Island was created in the 1930s by filling sand over underwater bay mud deposits, while Yerba Buena Island is a natural rock outcrop. The recordings showed a significant difference in amplification between the two adjacent sites. a Acceleration- 0.1 0.0 -0.1 0.1 0.0 -0.1 0 0 5 a) Which island has a soft soil condition? 10 10 15 15 Time-seconds 20 20 25 25 30 c) What was the approximate ratio of the peak ground acceleration at these sites? 30 b) Which recording was from Treasure Island and which one was from Yerba Buena Island? In other words, which site, soft soil or stiff rock, produced the larger shaking?

Structural Analysis

6th Edition

ISBN:9781337630931

Author:KASSIMALI, Aslam.

Publisher:KASSIMALI, Aslam.

Chapter2: Loads On Structures

Section: Chapter Questions

Problem 1P

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Yerba Buena Island in a large rock outcrop in San Francisco Bay. Treasure Island is an artificial island formed by hydraulic filling on a shallow zone adjacent to Yerba Buena. The hydraulic fill basically consists of loose, fine to medium, silt and sand, with occasional clay zones. The islands are located roughly midway between the San Andreas Fault to the West and the Hayward fault to the East. During 1989 earthquake, ground acceleration was recorded at both islands. Examine the seismographs image from 1989 earthquake and answer the following questions:
Yerba Buena Island in a large rock outcrop in San Francisco Bay. Treasure Island is an artificial island formed by hydraulic filling on a shallow zone adjacent to Yerba Buena. The hydraulic fill basically consists of loose, fine to medium, silt and sand, with occasional clay zones. The islands are located roughly midway between the San Andreas Fault to the West and the Hayward fault to the East. During 1989 earthquake, ground acceleration was recorded at both islands. Examine the attached seismographs from 1989 earthquake and answer the following questions:
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