In‐Situ Stress Measurement and Tectonic Stress Field in the Lanzhou‐Maqu Region of China

Abstract

The study region is a strongly deformed frontal area of the Tibet plateau caused by the northeastward compression of Indian plate. The study on the present tectonic stress field in this region has important meaning for the research of continental dynamics. The values and directions of the ground stress at several sites of Lanzhou‐Maqu area are given in the paper using piezomagnetic stress gauge overcoring method. The measurement sites are situated in Ayishan, Dashui, Gahai, Ma'ai, and Qingshui. The previous stress data are also analyzed for systematically studying the tectonic stress field in the region of Lanzhou‐Maqu and its adjacent area. The result shows that the values of ground stress in depths of tens meters are medium as compared to that in other areas, and increase with depth, the increase rate differs in different tectonic units. The overall direction of maximum horizontal principal stress is northeast with a small variation in different tectonic units. The direction of maximum horizontal principal stress is nearly west‐east in Ordos block, NNW‐NE in Hexizoulang. The direction of maximum principal stress changes considerably in the southeast part of Qilanshan Mountains. The west Qinling Mountain is a transition zone of ground stress. The direction of maximum horizontal principal stress changes gradually from NE in the north to EW in the middle and SEE in the south part. The results agree with the strain field in this area from GPS observation.

The 2019 MW 5.7 Changning Earthquake, Sichuan Basin, China: A Shallow Doublet With Different Faulting Styles

“…The stress was calculated from 39 focal mechanisms of 2008-2016 (Liu et al, 2019). Using the given stress, similarly as Hainzl et al (2016), we resolve shear and normal tractions on both nodal planes and identify the planes with greater shear instability (defined by (Liu et al, 2019;Ran et al, 2008;Wang et al, 2015;Yi et al, 2019;Zhu & He, 2014). The upper inset shows the pre-2019 regional stress field (Liu et al, 2019)-the principal axes (azimuth/plunge) and the shape ratio R. Faults as in Figure 1.…”

Influence of different configurations of western North Pacific anticyclone and Siberian high on spring climate over China

“…To investigate the spring climate anomalies, a gridded daily dataset named CN05.1 from 1961 to the present is employed in this study. The CN05.1 is on a 0.25° × 0.25° grid over the Chinese mainland and is derived by the interpolation of climate anomalies from over 2,400 observing stations (Wu and Gao, 2013). The variables analysed in this study include precipitation amount and SAT.…”

Mechanical mechanism of in situ stress ratio limit and its evolution simulation

“…With the increase of depth, the maximum horizontal principal stress gradually shows a linear relationship, but the mechanical essence of this phenomenon has not been clarified. In this article, 452 measured in situ stress data at home and 122 foreign in situ stress data (Liao et al, 1985;Liang et al, 1991;Wang et al, 2000;Li et al, 2004;Li et al, 2007;Li et al, 2008;Wu et al, 2008;Chen et al, 2012;Du et al, 2013;Tan et al, 2014;Niu et al, 2015;Zhang et al, 2015;Song et al, 2018) are counted. The distribution of depth and stress ratio is shown in Figure 1.…”