Plate coupling and strain in the far western Aleutian arc modeled from GPS data

• Published in: Geophysical research letters Vol. 44; no. 7; pp. 3176 - 3183
• Main Authors: Kogan, Mikhail G., Frolov, Dmitry I., Vasilenko, Nikolay F., Freymueller, Jeffrey T., Steblov, Grigory M., Ekström, Göran, Titkov, Nikolay N., Prytkov, Alexandr S.
• Format: Journal Article
• Language: English
• Published: Washington John Wiley & Sons, Inc 16.04.2017
• Subjects: Aleutian; Boundaries; Coupling; Geological faults; Global positioning systems; GPS; Islands; Komandorsky; Locking; oblique; sliver; Slivers; subduction; Tectonics; Transforms; INW, Russia, Kamchatskaya; North America; IN, Pacific
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1002/2017GL072735

The Aleutian and Kuril‐Kamchatka arcs meet at a triple junction of the Pacific (PAC), Bering (BER), and North American (NAM) plates. We invert GPS observations from the westernmost Aleutian (Komandorsky) Islands and Kamchatka for the fault locking depth and block motion in the far western Aleutian transform boundary. Three boundary models were considered: (1) only the Aleutian thrust fault without a trench‐normal component, (2) only a strike‐slip fault in the back arc north of the Komandorsky Islands, and (3) a rigid Komandorsky sliver bounded by the Aleutian and back‐arc faults. Observed velocities prefer Model 3, with a secular westward sliver velocity of 51 mm/a relative to NAM (two thirds of the total PAC‐NAM motion). The observed velocities are ~10% slower because of elastic strain from boundary faults. The best fitting locking depth of faults bounding the sliver is 12 km, which is similar to depths observed in diverse tectonic environments. Key Points We consider three models of the transform plate boundary at the far western Aleutians GPS velocities on the far western Aleutians are best fit by the model with a rigid Komandorsky block at the boundary Our best fitting model suggests that the Komandorsky block moves westward toward Kamchatka at the secular speed of 51 mm/a