| Anisotropy from SKS splitting across the Pacific-North America plate boundary offshore southern California | |
| Ramsay, J (Ramsay, Joseph)1; Kohler, MD (Kohler, Monica D.)2; Davis, PM (Davis, Paul M.)1; Wang, XG (Wang, Xinguo)3,4; Holt, W (Holt, William)4; Weeraratne, DS (Weeraratne, Dayanthie S.)5; Kohler, MD | |
| Source Publication | GEOPHYSICAL JOURNAL INTERNATIONAL
 |
| 2016 | |
| Volume | 207Issue:1Pages:244-258 |
| DOI | 10.1093/gji/ggw271 |
| Abstract | SKS arrivals from ocean bottom seismometer (OBS) data from an offshore southern California deployment are analysed for shear wave splitting. The project involved 34 OBSs deployed for 12 months in a region extending up to 500 km west of the coastline into the oceanic Pacific plate. The measurement process consisted of removing the effects of anisotropy using a range of values for splitting fast directions and delay times to minimize energy along the transverse seismometer axis. Computed splitting parameters are unexpectedly similar to onland parameters, exhibiting WSW-ENE fast polarization directions and delays between 0.8 and 1.8 s, even for oceanic plate sites. This is the first SKS splitting study to extend across the entire boundary between the North America and Pacific plates, into the oceanic part of the Pacific plate. The splitting results show that the fast direction of anisotropy on the Pacific plate does not align with absolute plate motion (APM), and they extend the trend of anisotropy in southern California an additional 500 km west, well onto the oceanic Pacific plate. We model the finite strain and anisotropy within the asthenosphere associated with density-buoyancy driven mantle flow and the effects of APM. In the absence of plate motion effects, such buoyancy driven mantle flow would be NE-directed beneath the Pacific plate observations. The best-fit patterns of mantle flow are inferred from the tomography-based models that show primary influences from foundering higher-density zones associated with the history of subduction beneath North America. The new offshore SKS measurements, when combined with measurements onshore within the plate boundary zone, indicate that dramatic lateral variations in density-driven upper-mantle flow are required from offshore California into the plate boundary zone in California and western Basin and Range. |
| Subject Area | 地球物理学 |
| WOS ID | WOS:000384651200017 |
| Language | 英语 |
| Indexed By | SCI |
| Keyword | Seismic Anisotropy Mantle Flow Olivine Polycrystals Joint Inversion United-states Finite Strain Wave Shear Beneath Dynamics |
| Cooperation Status | 国际 |
| Department | 碰撞与隆升 |
| Subtype | Article |
| Citation statistics | |
| Document Type | 期刊论文 |
| Identifier | http://ir.itpcas.ac.cn/handle/131C11/7580 |
| Collection | 图书馆 |
| Corresponding Author | Kohler, MD |
| Affiliation | 1.Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90095 USA 2.CALTECH, Dept Mech & Civil Engn, Pasadena, CA 91125 USA 3.Chinese Acad Sci, Inst Tibetan Plateau Res, Key Lab Continental Collis & Plateau Uplift, Beijing, Peoples R China 4.SUNY Stony Brook, Dept Geosci, Stony Brook, NY 11794 USA 5.Calif State Univ Northridge, Dept Geol Sci, Northridge, CA 91330 USA |
| Recommended Citation GB/T 7714 | Ramsay, J ,Kohler, MD ,Davis, PM ,et al. Anisotropy from SKS splitting across the Pacific-North America plate boundary offshore southern California[J]. GEOPHYSICAL JOURNAL INTERNATIONAL,2016,207(1):244-258. |
| APA | Ramsay, J .,Kohler, MD .,Davis, PM .,Wang, XG .,Holt, W .,...&Kohler, MD.(2016).Anisotropy from SKS splitting across the Pacific-North America plate boundary offshore southern California.GEOPHYSICAL JOURNAL INTERNATIONAL,207(1),244-258. |
| MLA | Ramsay, J ,et al."Anisotropy from SKS splitting across the Pacific-North America plate boundary offshore southern California".GEOPHYSICAL JOURNAL INTERNATIONAL 207.1(2016):244-258. |
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| File Name/Size | DocType | Version | Access | License | ||
| V.207(1) 244-258 201（4497KB） | 期刊论文 | 作者接受稿 | 开放获取 | CC BY-NC-SA | View Application Full Text | |
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