Active tectonics and intracontinental earthquakes in China: The kinematics and geodynamics

Abstract

China is a country of intense intracontinental seismicity. Most earthquakes in western China occur within the diffuse Indo-Eurasian plate-boundary zone, which extends thousands of kilometers into Asia. Earthquakes in eastern China mainly occur within the North China block, which is part of the Archean Sino-Korean craton that has been thermally rejuvenated since late Mesozoic. Here, we summarize neotectonic and geodetic results of crustal kinematics and explore their implications for geodynamics and seismicity using numerical modeling. Quaternary fault movements and global positioning system (GPS) measurements indicate a strong infl uence of the Indo-Asian collision on crustal motion in continental China. Using a spherical three-dimensional (3-D) fi nite-element model, we show that the effects of the collisional plate-boundary force are largely limited to western China, whereas gravitational spreading of the Tibetan Plateau has a broad impact on crustal deformation in much of Asia. The intense seismicity in the North China block, and the lack of seismicity in the South China block, may be explained primarily by the tectonic boundary conditions that produce high deviatoric stresses within the North China block but allow the South China block to move coherently as a rigid block. Within the North China block, seismicity is concentrated in the circum-Ordos rifts, refl ecting the control of lithospheric heterogeneity. Finally, we calculated the change of Coulomb stresses associated with 49 major (M ≥ 6.5) earthquakes in the North China block since 1303. The results show that ~80% of these events occurred in regions of increasing Coulomb stresses caused by previous events.

Roaming earthquakes in China highlight midcontinental hazards

“…This is certainly true for the Shanxi rift zone (Figure 1e), which has developed since the Pliocene or earlier (since at least 5.3 million years ago) and produced more than 36 large events (M >6.5) in the past 700 years [Liu et al, 2007]. The same cannot be said for the Tangshan, Haicheng, and Xingtai regions, where no active tectonics or major active faults were recognized before the recent large earthquakes.…”

Folded Basinal Compartments of the Southern Mongolian Borderland: A Structural Archive of the Final Consolidation of the Central Asian Orogenic Belt

“…The Beishan region shows less evidence for Late Cenozoic reactivation, however, several Quaternary deforming belts cut the region and geodetic data suggest northeast-directed crustal displacements on the order of 5 mm/year relative to a fixed Siberia [15,62]. In addition, the tectonic geomorphology of the Beishan region reveals a number of upthrust basement blocks with low mountain front sinuosity and Quaternary fan complexes along their fronts suggesting localized crustal rejuvenation [15].…”

“…The region is tectonically active today as indicated by widespread historical seismicity including the 1957 M = 8.1 Gobi Altai earthquake [56][57][58][59]. Geodetic data indicate 1-10 mm/year northeast and eastward crustal motions relative to a fixed Siberia [60][61][62]. A wide array of Quaternary northwest striking thrust faults and east-west striking sinistral strike-slip faults is documented throughout the Gobi Altai region [15,31].…”

Seismodynamics and deep internal origin of the North China zone of strong earthquakes

“…Под воздействием ИндоАвстралийской плиты происходит разрушение окраины континента, дробление его коры на тектонические блоки, постепенно сползающие на восток в сторону Тихого океана [Gatinsky, Rundquist, 2004; Зоненшайн и др., 1990; Molnar, Tapponier, 1975; и др.]. Наиболее ярко этот процесс отражается в ре зультатах GPSизмерений, которые для Северного Ки тая показывают перемещения блоков с запада на вос ток в субширотном направлении [Liu et al, 2007]. Судя по сводке фокальных механизмов [Ван и др., 1990], с П р и м е ч а н и е. Названия и параметры землетрясений по [Ван и др., 1990], ∆ Т -длительность паузы между данным землетрясением и предыдущим.…”

“…рис. 1, А) субширотным траекториям тектониче ских перемещений по результатам GPSизмерений [Liu et al, 2007]. Но с этой ориентировкой, как отмечалось (см.…”