A Caltech Library Service

Sediment-Induced Amplification in the Northeastern United States: a Case Study in Providence, Rhode Island

Fischer, Karen M. and Salvati, Lynn A. and Hough, Susan E. and Gonzalez, Edward and Nelsen, Chad E. and Roth, Erich G. (1995) Sediment-Induced Amplification in the Northeastern United States: a Case Study in Providence, Rhode Island. Bulletin of the Seismological Society of America, 85 (5). pp. 1388-1397. ISSN 0037-1106.

PDF - Published Version
See Usage Policy.


Use this Persistent URL to link to this item:


We employed ambient-noise measurements to assess the potential for seismic site response in sediment-filled valleys that intersect beneath downtown Providence, Rhode Island. At eight valley stations and at two sites on an adjacent bedrock highland, we recorded ground motion from two types of sources: pile drivers at a local construction site and ambient microtremors. At all valley sites where sediment thicknesses exceed 10 m, spectral ratios contain amplitude peaks at frequencies of 1.5 to 3.0 Hz. In contrast, spectral ratios from the two sites on the bedrock highland where sediment cover is less than 4-m thick are relatively flat within this frequency range. A variety of borehole logs identified two fundamental sediment types (soft sediment and a consolidated glacial till) and were used to map layer thicknesses over the entire study region. Refraction data constrained P-wave velocity in the bedrock to be 3680 ± 160 m/sec and indicated two soft-sediment layers with P-wave velocities of 300 ± 50 and 1580 ± 120 m/sec. Using a one-dimensional reflection matrix technique, we matched the spectral-ratio peak observed at each valley site with the frequency of fundamental resonance predicted for local layer thicknesses and velocities. A positive correlation between the best-fitting soft-sediment velocities and bedrock depth may reflect greater compaction in the deepest sediments or a locally two-dimensional sediment resonance at the deepest sediment sites. We conclude that unconsolidated sediment layers under downtown Providence have the potential to amplify earthquake ground motion at frequencies damaging to engineered structures.

Item Type:Article
Related URLs:
URLURL TypeDescription
Hough, Susan E.0000-0002-5980-2986
Additional Information:© 1995, by the Seismological Society of America. Manuscript received 10 October 1994. Research supported by the U.S. Geological Survey (USGS), Department of the Interior, under USGS Award Number 1434-92-G-2166. The views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the U.S. Government. Seismometers were provided by the National Center for Earthquake Engineering Research (NCEER). Thanks to D. W. Forsyth, L. Seeber, P. R. Slice, and numerous Brown University geophysics students for their assistance in the field, and to M. Imse of the Providence Convention Center Authority and M. Unger of the C.E. Maguire Group for access to geotechnical reports.
Funding AgencyGrant Number
Issue or Number:5
Record Number:CaltechAUTHORS:20140806-142243693
Persistent URL:
Official Citation:Karen M. Fischer, Lynn A. Salvati, Susan E. Hough, Edward Gonzalez, Chad E. Nelsen, and Erich G. Roth Sediment-induced amplification in the Northeastern United States: A case study in Providence, Rhode Island Bulletin of the Seismological Society of America, October 1995, v. 85, p. 1388-1397
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:48119
Deposited By: Ruth Sustaita
Deposited On:06 Aug 2014 21:36
Last Modified:09 Mar 2020 13:18

Repository Staff Only: item control page