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Site characterization for urban seismic hazards in lower Manhattan, New York City, from microtremor array analysis

Geophysical Research Letters

By:
, , , , , and
DOI: 10.1029/2008GL036444

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Abstract

We characterize the shear-wave velocity (Vs) of soil deposits in lower Manhattan at six sites using the SPAC and HVSR microtremor methods. The soil Vs ranges from 140 m/s to 300 m/s over bedrock. We believe that bedrock depth is constrained to ±15% with these microtremor data, but an accurate quantification of bedrock Vs is unattainable because of low spectral coherency at frequencies below 3 Hz. HVSR data corroborate the SPAC microtremor results at sites based on good alignment of theoretical Rayleigh ellipticity peaks, 1D SH amplifications, and peak HVSR. Resonant frequencies vary between 1.4 and 5.5 Hz between the sites from both observed HVSR and predicted 1D SH amplification. Shear-wave velocities to 30 m classify the sites as C, D, or E. This study demonstrates that given relatively shallow bedrock depth the SPAC method can work in extremely urbanized areas.

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Additional publication details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Site characterization for urban seismic hazards in lower Manhattan, New York City, from microtremor array analysis
Series title:
Geophysical Research Letters
DOI:
10.1029/2008GL036444
Volume:
36
Issue:
3
Year Published:
2009
Language:
English
Publisher:
American Geophysical Union
Publisher location:
Washington
Description:
5 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Geophysical Research Letters
Country:
United States
State:
New York
City:
New York
Online Only (Y/N):
N
Additional Online Files (Y/N):
N