Slip Rate Variation Along the Kunlun Fault (Tibet): Results From New GPS Observations and a Viscoelastic Earthquake-Cycle Deformation Model
Slip Rate Variation Along the Kunlun Fault (Tibet): Results From New GPS Observations and a Viscoelastic Earthquake-Cycle Deformation Model
复制标题
昆仑断层（西藏）沿线滑移率变化：新 GPS 观测结果和粘弹性地震循环变形模型
DOI：
10.1029/2019gl081940
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发表时间：
2019-03-16
影响因子：
5.2
通讯作者：
Wang, Kai
中科院分区：
文献类型：
--
作者：
Diao, Faqi;Xiong, Xiong;Wang, Kai
昆仑断裂的滑动速率及其空间变化在青藏高原东北部的构造演化中起着重要作用。在这里的托索湖（TL）段的KLF，这仍然是有争议的各种地质观测，与密集的全球定位系统观测剖面的滑动速率进行了研究。用粘弹性地震周期变形模型估算TL段的滑动速率为5.5 ± 0.7 mm/a，而弹性模型估算的滑动速率为9.2 ± 1.1 mm/a。结合前人的研究结果，我们推断KLF的滑动速率可能是从TL段向东端逐渐减小，而不是沿着断层保持一致或在最东端150 km内迅速减小。估算的下地壳粘度（近似10（18）Pa.s）与震后研究推断的值一致，这表明该地区下地壳韧性较弱。简明语言概要昆仑断裂（KLF）是青藏高原上主要的左旋走滑断裂之一，并承担了高原向东运动的重要部分。KLF带的滑动速率及其沿着向的空间变化对了解KLF带的构造演化、地壳形变和地震活动具有重要作用。然而，滑动速率如何沿断层沿着变化仍然存在争议。本文利用全球定位系统（GPS）在托索湖段的密集速度剖面，对KLF东部的滑动速率进行了探测。粘弹性地震周期形变模型的结果表明，KLF的滑动速率从托索湖段向东端逐渐减小，而不是像以前不同观测所推断的那样沿断层沿着保持一致或在断层最东端150 km内迅速减小。我们的研究结果还突出了粘弹性松弛效应在地震周期。
The slip rate and its spatial variations of the Kunlun fault (KLF) play important roles in the tectonic evolution of the northeastern Tibetan Plateau. Here the slip rate of the Tuosuo Lake (TL) segment of the KLF, which remains controversial from various geological observations, is investigated with a dense Global Positioning System observation profile. With a viscoelastic earthquake-cycle deformation model, the slip rate of the TL segment is estimated to be 5.5 +/- 0.7 mm/a, in comparison with an overestimated value of 9.2 +/- 1.1 mm/a from an elastic model. Combined with previous results, we infer that the slip rate of the KLF likely decreases gradually from the TL segment toward the eastern tip, rather than remaining uniform along the fault or decreasing rapidly within the easternmost 150 km. The estimated lower crust viscosity (similar to 10(18) Pa.s) agrees with values inferred from postseismic studies, which suggests a weak ductile lower crust in this region.Plain Language Summary The Kunlun fault (KLF) is one of the major left-lateral strike-slip faults on the Tibetan Plateau and accommodates a significant portion of the plateau's eastward motion. The slip rate and its spatial variations along the KLF play important roles in understanding the associated tectonic evolution, crustal deformation, and seismic activity. However, how the slip rate varies along the fault remains controversial. Here a dense Global Positioning System velocity profile across the Tuosuo Lake segment is used to probe the slip rate of the eastern KLF. The results inferred from a viscoelastic earthquake-cycle deformation model suggest that the slip rate of the KLF decreases gradually from the Tuosuo Lake segment toward its eastern tip, rather than remaining uniform along the fault or decreasing rapidly within the easternmost 150km of the fault as inferred previously from different observations. Our results also highlight the viscoelastic relaxation effect during the earthquake cycle.