Extension rates across the northern Shanxi Grabens, China, from Quaternary geology, seismicity and geodesy
Extension rates across the northern Shanxi Grabens, China, from Quaternary geology, seismicity and geodesy
复制标题
DOI：
10.1093/gji/ggx031
复制
发表时间：
2017-05
影响因子：
2.8
通讯作者：
T. Middleton;J. Elliott;E. Rhodes;S. Sherlock;R. Walker;Weitao Wang;Jingxing Yu;Yu Zhou
中科院分区：
文献类型：
--
作者：
T. Middleton;J. Elliott;E. Rhodes;S. Sherlock;R. Walker;Weitao Wang;Jingxing Yu;Yu Zhou
地质学、地震学和大地测量学的应变率之间的差异表明地壳变形率以及地震危险性随时间而变化。在中国北方鄂尔多斯高原东北角的北方山西地堑中，以前的研究发现，在95 °和180 °之间的方位角处，伸展速率在0和6 mm/a之间。在本文中，我们确定整个北方山西地堑的伸展速率：偏移地貌特征和各种第四纪测年技术（包括新的IRSL和Ar-Ar年龄）; Kostrov求和使用700年的历史地震目录;和最近的战役GPS测量。我们观察到第四纪、地震和大地测量的应变率之间有很好的一致性，并且我们发现北方地堑在方位角为151 °处以1 ~ 2 mm/a的速度伸展。延伸的方位角受到特别好的限制，可以从小地震目录中可靠地推断出来。我们没有发现任何实质性的变化，在扩展率随时间的证据，虽然有一个显着的地震矩率赤字自1750年以来。这种缺陷可能表明大范围内复杂的断层相互作用，变形的地震适应，或者我们在地震周期中处于相当晚的阶段，在相对较近的将来可能会发生更大的地震。
Discrepancies between geological, seismic and geodetic rates of strain can indicate that rates of crustal deformation, and hence seismic hazard, are varying through time. Previous studies in the northern Shanxi Grabens, at the northeastern corner of the Ordos Plateau in northern China, have found extension rates of anywhere between 0 and 6 mm/a at an azimuth of between 95 and 180 °. In this paper we determine extension rates across the northern Shanxi Grabens from: offset geomorphological features and a variety of Quaternary dating techniques (including new IRSL and Ar-Ar ages); a Kostrov summation using a 700 year catalogue of historical earthquakes; and recent campaign GPS measurements. We observe good agreement between Quaternary, seismic and geodetic rates of strain, and we find that the northern Shanxi Grabens are extending at around 1 to 2 mm/a at an azimuth of ≈ 151 °. The azimuth of extension is particularly well constrained and can be reliably inferred from catalogues of small earthquakes. We do not find evidence for any substantial variations in extension rate through time, though there is a notable seismic moment rate deficit since 1750. This deficit could indicate complex fault interactions across large regions, aseismic accommodation of deformation, or that we are quite late in the earthquake cycle with the potential for larger earthquakes in the relatively near future.