 |
| Titel |
Lithosphere stress changes due to groundwater unloading in North China Plain |
| VerfasserIn |
Yajin Pang, Huai Zhang, Yaolin Shi |
| Konferenz |
EGU General Assembly 2015
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250101474
|
| Publikation (Nr.) |
 EGU/EGU2015-625.pdf |
|
|
|
|
|
| Zusammenfassung |
| During the past 50 years, excessive groundwater pumping has led to the continuous decline of
groundwater table in North China Plain, which becomes one of the global hotspots of
groundwater depletion. Over most of the rural areas of the plain, the shallow aquifer has
experienced a water-table decline of more than 15m, with greater declines up to 50m in most
urban centres, such as Beijing, Tangshan, Shijiangzhuang and so forth in 1960-2000. The
entire groundwater depletion area covers a total area of approximately 56,273 km2 , more
than 40% of the North China Plain. The vast area of enormous groundwater exploitation in
North China Plain will definitely unload the lithosphere and create stress perturbations, the
problem is if the stresses change large enough to affect tectonic activities. In this essay,
we set up a 3 dimensional numerical visco-elastic model to discuss the effect of
groundwater over-pumping on the lithosphere deformation and stress state in North China
Plain.
Based on the records of total groundwater-table decline during 1960-2010 in North China
Plain, we estimate the accumulated deformation and lithosphere stress due to unloading of
human-induced groundwater depletion. The area in the model ranges from 34° To
42°N, and 112° To 119°E, including the major groundwater depression cones in
North China Plain. According to the simulating result, the maximum surface vertical
uplift caused by groundwater unloading is 8cm. Meanwhile cumulative horizontal
crustal stress changes near the surface goes up to 100kPa, and up to 40kPa at 15km
depth where most earthquakes occurred in this area. The tectonic compressive stress
rate is about 0.25kPa per year. Therefore, the stress changes due to groundwater
pumping is significant compared with the tectonic driven stress changes. As China
developed rapidly since 1978, the groundwater table mainly declined after 1978.
Taking the earthquake catalog in the vicinity of groundwater depression zone into
consideration, we find that the earthquake events between1978-2014 are obviously
less than that during the former 35-year period. There are 11 earthquakes with
magnitude greater than M6.0 occurred during 1942-1977 and none in the period
of 1978-2014. Although the seismicity may have natural fluctuations, the human
effects cannot be excluded, as earthquake events are controlled by regional tectonic
stress, which is significantly perturbed by groundwater overpumping in North China
Plain. This study also suggests that earth is a complex system, in which each part
interacts with others. Human activities on the earth surface may not only affect the
atmosphere and the hydrosphere as well known, but also affect the lithosphere. |
|
|
|
|
|
|