Site-Response Maps for the Los Angeles Region
Based on Earthquake Ground Motions


Table 3.--Average amplification

Average amplification factors* 

Average

S-wave 

velocity

Surficial geologic unit 

Short Period 

Intermediate Period 

(2.0 to 6.0 Hz) 

(0.5 to 1.5 Hz) 

(1)  SD(1)  (2)  (1)  SD(1)  (2)  (m/s)   
1.0  0.09  1.0  1.0  0.13  1.0  710  Mesozoic and pre-Mesozoic crystalline and metasedimentary rocks. 
1.8  0.12  1.2  1.8  0.17  1.5  407  Tertiary and pre-Tertiary sedimentary rocks. 
1.6  0.12  1.3  2.2  0.10  1.5  368  Pleistocene alluvium 
1.9  0.11  1.3  2.2  0.16  1.7  321  Holocene alluvium 

(1) Average amplification for all sites within the indicated surficial geologic unit.

(2) Amplification from regression relationship between S-wave velocity and site response using

average S-wave velocities for the indicated geologic unit.

SD(1) Standard deviation for average (1).

*Normalized to 1.0 for Mesozoic units. (pre-normalization values for Mesozoic units: 1.4, short period (1); 1.9, short period (2); 1.0, intermediate period (1); 1.3, intermediate period (2))
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