Stable Continental Region Earthquakes in South China

Abstract

Ð This paper reviews some remarkable characteristics of earthquakes in a Stable Continental Region (SCR) of the South China Block (SCB). The kernel of the SCB is the Yangtze platform solidi®ed in late Proterozoic time, with continental growth to the southeast by a series of fold belts in Paleozoic time. The facts that the deviatoric stress is low, the orientations of the major tectonic features in the SCB are substantially normal to the maximum horizontal principal stress, and a relatively uniform crust, seem to be the major reasons for lack of signi®cant seismicity in most regions of the SCB. Earthquakes in this region are mainly associated with three seismic zones: (1) the Southeast China Coast seismic zone related to Guangdong-Fujian coastal folding belt (associated with Eurasia-Philippine Sea plate collision); (2) the Southern Yellow Sea seismic zone associated with continental shelf rifts and basins; and (3) the Downstream Yangtze River seismic zone spatially coinciding with Tertiary rifts and basin development. All three seismic zones are close to one or two major economic and population centers in the SCB so that they pose signi®cant seismic hazards. Earthquake focal mechanisms in the SCB are consistent with strikeslip to normal faulting stress regimes. Because of the global and national economic signi®cance of the SCB and its dense population, the seismic hazard of the region is of outstanding importance. Comparing the SCB with another less developed region, a pending earthquake with the same size and tectonic setting would cause substantially more severe social and economic losses in the SCB. This paper also compiles an inventory of historic moderate to great earthquakes in the SCB; most of the data are not widely available in English literature.

Multilayer stress from gravity and its tectonic implications in urban active fault zone: A case study in Shenzhen, South China

“…The horizontal principal compressive stress is dominantly NNW-and NW-trending, almost perpendicular to the major fault trend. The stress orientation is consistent with the regional tectonic background (Liu, 2001). The maximum horizontal shear stress is mostly less than 1 MPa (Tan et al, 2000).…”

Local intraplate earthquake considerations for Singapore

“…In addition to tremors detected in recent years within the peninsular, intraplate earthquake activities have also been recorded in the South China Sea basin and in South China itself (Wang, Geller and Stein 1979;Liu 2001). Given that the destructive potentials of an intraplate earthquake (of magnitude up to 6) diminish rapidly with distance earthquakes of this scale occurring offshore is of little engineering significance unlike those large-magnitude earthquakes generated by the subduction sources at tectonic plate margins.…”

Velocity structure heterogeneity and tectonic motion in and around the Tan–Lu fault of China

“…At present, Northern China is a seismically active region, while the Yangtze region is seismically quiet (Li et al, 2006;Zhao et al, 1990;Xu et al, 2007;Liu, 2001). Seismic velocity structure analyses can usually be employed for studies of tectonic motion and evolution (Widiyantoro et al, 2000;Zhao et al, 2011Zhao et al, , 1997Zhao, 1985).…”