Imaging the crust and uppermost mantle of north central Alaska using the joint inversion of ambient seismic noise correlation and receiver function

• Main Author: Torbeck, Douglas
• Other Authors: Song, Xiaodong
• Language: English
• Published: 2012
• Subjects: Seismology; Alaska; Fairbanks; Brooks Range; north slope; Prudhoe Bay
• Online Access: http://hdl.handle.net/2142/30949

Seismic velocity models obtained from the joint inversion of ambient seismic noise correlation and receiver function analysis show a representation of the crustal and uppermost mantle velocity structure in north central Alaska. Due to the lack of station coverage and inhospitable terrain, the structure beneath northern Alaska remains largely unexplored. The stations used in this study consist mainly of the temporarily deplored ARTIC seismic array from mid 2005 to mid 2007. This linear array runs north from Fairbanks, AK to Prudhoe Bay, AK. The source for the surface wave tomography is ambient seismic noise correlation, which correlates the background noise from a seismic station’s continuous record with the noise from another station's record. This returns an empirical surface wave Green function between the station pair, which is used to extract Rayleigh wave group and phase velocity dispersions. The dispersion measurements between station pairs are then used to invert for surface dispersions at the discreet grids along the linear array. The receiver function analysis uses the P to S conversions at velocity boundaries. Because of their different sensitivities to the subsurface structure, the two data sets are combined to invert for a 1-D, S velocity profile under each station. Preliminary results show shallow crustal structures including the sedimentary basins in the Central Uplands and Lowlands, the Colville Basin on the North Slope, and a high velocity zone under the southern part of the Brooks Range. The Moho is well mapped, and is deepest under the Brooks Range and is average crustal depth under the North Slope and Central Uplands and Lowlands. A significant low velocity zone is observed in the uppermost mantle under the southern slope of the Brooks Range. These results set the stage for the upcoming USArray deployment in Alaska for the understanding of the tectonic structure and evolution in the North America frontier.