Seismic structure of the crust and uppermost mantle of North America and adjacent oceanic basins: A synthesis
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Abstract
We present a new set of contour maps of the seismic structure of North America and the surrounding ocean basins. These maps include the crustal thickness, whole-crustal average P-wave and S-wave velocity, and seismic velocity of the uppermost mantle, that is, Pn and Sn. We found the following: (1) The average thickness of the crust under North America is 36.7 km (standard deviation [s.d.] ±8.4 km), which is 2.5 km thinner than the world average of 39.2 km (s.d. ± 8.5) for continental crust; (2) Histograms of whole-crustal P- and S-wave velocities for the North American crust are bimodal, with the lower peak occurring for crust without a high-velocity (6.9–7.3 km/sec) lower crustal layer; (3) Regions with anomalously high average crustal P-wave velocities correlate with Precambrian and Paleozoic orogens; low average crustal velocities are correlated with modern extensional regimes; (4) The average Pn velocity beneath North America is 8.03 km/sec (s.d. ± 0.19 km/sec); (5) the well-known thin crust beneath the western United States extends into north-west Canada; (6) the average P-wave velocity of layer 3 of oceanic crust is 6.61 km/sec (s.d. ± 0.47 km/sec). However, the average crustal P-wave velocity under the eastern Pacific seafloor is higher than the western Atlantic seafloor due to the thicker sediment layer on the older Atlantic seafloor.
Suggested Citation
Chulick, G., and Mooney, W.D., 2002, Seismic structure of the crust and uppermost mantle of North America and adjacent oceanic basins: A synthesis: Bulletin of the Seismological Society of America, v. 92, no. 6, p. 2478-2492, https://doi.org/10.1785/0120010188.
ISSN: 1943-3573 (online)
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Seismic structure of the crust and uppermost mantle of North America and adjacent oceanic basins: A synthesis |
| Series title | Bulletin of the Seismological Society of America |
| DOI | 10.1785/0120010188 |
| Volume | 92 |
| Issue | 6 |
| Year Published | 2002 |
| Language | English |
| Publisher | Geological Society of America |
| Contributing office(s) | Earthquake Science Center |
| Description | 15 p. |
| First page | 2478 |
| Last page | 2492 |
| Other Geospatial | North America |