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Velocity field in Asia inferred from Quaternary fault slip rates and Global Positioning System observations
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| Zeitschriftentitel: | Journal of Geophysical Research: Solid Earth |
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| Personen und Körperschaften: | , , , , , |
| In: | Journal of Geophysical Research: Solid Earth, 105, 2000, B8, S. 19185-19209 |
| Format: | E-Article |
| Sprache: | Englisch |
| veröffentlicht: |
American Geophysical Union (AGU)
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| Schlagwörter: |
| Zusammenfassung: | <jats:p>We perform a joint inversion of Quaternary strain rates and 238 Global Positioning System (GPS) velocities in Asia for a self‐consistent velocity field. The reference frames for all geodetic velocity observations are determined in our inversion procedure. India (IN) moves relative to Eurasia (EU) about a pole of rotation at (29.78°N, 7.51°E, 0.353° Myr<jats:sup>−1</jats:sup>), which yields a velocity along the Himalaya within India that is ∼73–76% of the magnitude of the IN‐EU NUVEL‐1A velocity and a vector azimuth that is 8–10° clockwise of NUVEL‐1A IN‐EU vector azimuth. Relative to Eurasia, south China moves at 9–11 mm/yr in the direction 110–120° with a pole position (64.84°N, 156.74°E, 0.12° Myr<jats:sup>−1</jats:sup>). Amurian block motion has a pole position in a similar location but at a slower rate (64.61°N, 158.23°E, 0.077° Myr<jats:sup>−1</jats:sup>) and most of the Amurian‐Eurasia motion is accommodated by extension across Lake Baikal. Tarim Basin moves relative to Eurasia about a pole of rotation at (39.24°N, 98.2°E, −0.539° Myr<jats:sup>−1</jats:sup>) and ∼16–18 mm/yr of shortening is accommodated across the west central Tien Shan. There is distributed E‐W extension throughout both southern and north central Tibet. Within southern Tibet, between the longitudes of 77°E to 92°E, the deformation field accommodates ∼16–19 mm/yr of E‐W extension. We compare predicted seismic moment rates with those observed in this century in Asia. Total observed seismic moment rates within the entire area of central and east Asia (2.2×10<jats:sup>7</jats:sup> km<jats:sup>2</jats:sup>) in this century are 2.26±0.7×10<jats:sup>20</jats:sup> N m yr<jats:sup>−1</jats:sup> as compared with a predicted total rate of 2.03±0.066×10<jats:sup>20</jats:sup> N m yr<jats:sup>−1</jats:sup>. Comparisons between observed and predicted moment rates within 42 subregions reflect the generally unstable process of inferring long‐term seismic moment rates from a catalog of limited duration (94 years). An observation period of ∼10,000 years would be required to reduce uncertainties in observed seismic moment rate to the same size as the uncertainties in model tectonic moment rates, inferred from the joint inversion of GPS and Quaternary rates of strain. We show that in general, a better correlation with model tectonic moment rate is inferred from the seismicity catalog by considering the numbers of earthquakes above a cutoff magnitude (<jats:italic>m<jats:sub>b</jats:sub></jats:italic> ≥ 5.0, for the period January 1, 1965, to January 1, 1999).</jats:p> |
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| Umfang: | 19185-19209 |
| ISSN: |
0148-0227
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| DOI: | 10.1029/2000jb900045 |