Rapid deformation rates along the Wasatch Fault Zone, Utah, from first GPS measurements with implications for earthquake hazard
Rapid deformation rates along the Wasatch Fault Zone, Utah, from first GPS measurements with implications for earthquake hazard
复制标题
第一次 GPS 测量结果显示，犹他州瓦萨奇断层带的快速变形率对地震灾害有影响
DOI：
--
复制
发表时间：
1998
期刊：
影响因子：
--
通讯作者：
Robert B. Smith
中科院分区：
文献类型：
--
作者：
L. Martinez;C. Meertens;Robert B. Smith
通过重复的全球定位系统（GPS）测量，在犹他州瓦萨奇断层带向落基山脉的盆岭过渡处测量到异常高的地壳变形率。1992年至1995年的四次GPS野外活动以及与较早的（1962年至1991年）大地测量数据的比较显示，东西向的拉伸应变速率为0.05 ± 0.02 µ应变/年，相当于55 km宽区域内的水平位移速率为2.7 ±1.3 mm/年。这一速率超过了宽约800公里的盆地山脉省总延伸速率的20%。它也比Wasatch断层上晚第四纪断层滑动速率的平均值大两到三倍，比从历史地震的累积地震矩推断的位移速率大几十倍。虽然我们还不知道这种意想不到的当代变形的来源，可能的机制包括均匀的地壳伸展，加载的瓦萨奇和邻近的断层，和压力溶解蠕变。如果Wasatch断层受到这种高应变率的加载，它会使预期的峰值地面加速度从标准值显著增加。这些新发现表明了GPS在地震危险性评估中的重要性。
Anomalously high rates of crustal deformation have been measured at the Basin‐Range transition to the Rocky Mountains along the Wasatch fault zone, Utah, by repeated Global Positioning System (GPS) measurements. Four GPS field campaigns (1992–1995) and comparisons with older (1962–1991) geodetic data have revealed east‐west extensional strain at a rate of 0.05 ± 0.02 µstrain/yr corresponding to a 2.7 ±1.3 mm/yr rate of horizontal displacement across a 55‐km wide area. This rate is more than 20% of the total ∼12 mm/yr extension rate across of the ∼800‐km wide Basin and Range province. It is also two to three times larger than the average Late Quaternary fault slip rate on the Wasatch fault and tens of times larger than the displacement rates inferred from the cumulative seismic moments of historic earthquakes. While we do not yet know the source of this unexpected contemporary deformation, possible mechanisms include homogeneous crustal extension, loading of the Wasatch and adjacent faults, and pressure solution creep. If the Wasatch fault is being loaded by this high strain rate, it increases the expected peak ground acceleration significantly from standard values. These new findings demonstrate the importance of GPS in earthquake hazard assessment.