Ground motion in the presence of complex topography: Earthquake and ambient noise sources
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Abstract
To study the influence of topography on ground motion, eight seismic recorders were deployed for a period of one year over Poverty Ridge on the east side of the San Francisco Bay Area, California. This location is desirable because of its proximity to local earthquake sources and the significant topographic relief of the array (439 m). Topographic amplification is evaluated as a function of frequency using a variety of methods, including reference‐site‐based spectral ratios and single‐station horizontal‐to‐vertical spectral ratios using both shear waves from earthquakes and ambient noise. Field observations are compared with the predicted ground motion from an accurate digital model of the topography and a 3D local velocity model. Amplification factors from the theoretical calculations are consistent with observations. The fundamental resonance of the ridge is prominently observed in the spectra of data and synthetics; however, higher‐frequency peaks are also seen primarily for sources in line with the major axis of the ridge, perhaps indicating higher resonant modes. Excitations of lateral ribs off of the main ridge are also seen at frequencies consistent with their dimensions. The favored directions of resonance are shown to be transverse to the major axes of the topographic features.
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Ground motion in the presence of complex topography: Earthquake and ambient noise sources |
| Series title | Bulletin of the Seismological Society of America |
| DOI | 10.1785/0120130088 |
| Volume | 104 |
| Issue | 1 |
| Year Published | 2014 |
| Language | English |
| Publisher | Seismological Society of America |
| Publisher location | Stanford |
| Contributing office(s) | Denver Federal Center |
| Description | 16 p. |
| Larger Work Type | Article |
| Larger Work Subtype | Journal Article |
| Larger Work Title | Bulletin of the Seismological Society of America |
| First page | 451 |
| Last page | 466 |
| Country | United States |
| State | California |
| City | Santa Clara Valley |
| Other Geospatial | Diablo Mountains; Poverty Ridge |
| Online Only (Y/N) | N |
| Additional Online Files (Y/N) | N |
| Google Analytic Metrics | Metrics page |