Effects of lithospheric viscoelastic relaxation on the contemporary deformation following the 1959 Mw 7.3 Hebgen Lake, Montana, earthquake and other areas of the intermountain seismic belt
Effects of lithospheric viscoelastic relaxation on the contemporary deformation following the 1959 Mw 7.3 Hebgen Lake, Montana, earthquake and other areas of the intermountain seismic belt
复制标题
1959年蒙大拿州Mw 7.3赫布根湖地震和山间地震带其他地区后岩石圈粘弹性弛豫对当代形变的影响
DOI：
10.1029/2012gc004424
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发表时间：
2013
期刊：
影响因子：
3.7
通讯作者：
C. Puskas
中科院分区：
文献类型：
--
作者：
Wu‐Lung Chang;Robert B. Smith;C. Puskas
1959年MT Hebgen湖m7.3级正断层地震发生在黄石火山场附近的张拉应力区。1973年至2000年，在Hebgen湖断裂带周围，通过精确的三边测量和GPS测量获得了这次大地震后随时间变化的地壳变形数据。对断层两侧和断层附近基线长度变化的模拟揭示了瞬时流变学的横向变化，其中Hebgen湖断裂带附近的岩石圈比黄石火山系统附近的岩石圈更强。这些模型还表明，下地壳比上地幔更强，这与地震后和湖泊填充后弛豫（<~100年）的研究结果一致。此外，Hebgen湖和1983年6.9 Mw Borah峰地震产生的震后运动评价表明，高达~1 mm/yr的水平瞬变运动对震中附近当代区域地壳变形有重要贡献。对于Hebgen湖断裂以南约500 km的东部盆地和山脉，从观测到的与Bonneville湖反弹相关的隆起中导出了类似的流变模型，并用于评估与Wasatch断裂带最近的6次古地震和犹他州北部3次M≥5.6级历史地震相关的震后变形。结果表明，目前的水平震后运动≤0.1 mm/yr，在盆地和山脉连续GPS速度的水平不确定性范围内，明显小于Wasatch前缘当代1-3 mm/yr的扩展。
The 1959 Mw 7.3 Hebgen Lake, MT, normal‐faulting earthquake occurred in an extensional stress regime near the Yellowstone volcanic field. Time‐dependent crustal deformation data following this major earthquake were acquired by precise trilateration and GPS surveys from 1973 to 2000 around the Hebgen Lake fault zone. Modeling the changes of baseline lengths across and near the fault reveals a lateral variation of transient rheology, in which the lithosphere is stronger near the Hebgen Lake fault zone than in the vicinity of the Yellowstone volcano system. The models also imply that the lower crust is stronger than the upper mantle, in agreement with results from studies of postseismic and post‐lake‐filling relaxations (<~100 years). In addition, evaluations of the postseismic motion produced by the Hebgen Lake and the 1983 Mw 6.9 Borah Peak, ID, earthquakes indicate that horizontal transient motion of up to ~1 mm/yr contribute significantly to the contemporary regional crustal deformation near the epicentral areas. For the eastern Basin and Range, ~500 km south of the Hebgen Lake fault, similar rheologic models were derived from the observed uplift associated with the Lake Bonneville rebound and were used to evaluate the postseismic deformation associated with six most recent paleoearthquakes of the Wasatch fault zone and three M ≥ 5.6 historic earthquakes of northern Utah. The results show ≤0.1 mm/yr of horizontal postseismic motion at present time that are within the horizontal uncertainties of continuous GPS velocity from the Basin and Range and significantly smaller than the contemporary extension of 1–3 mm/yr in the Wasatch Front.