Mechanisms

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SITE POTENTIAL MECHANISMS DEVELOPING PROCESS
1 – Queretaro Overexploitation of groundwater and the presence of intercalated compressible granular units and stiff rock layers led to differential subsidence and the presence of fissures. Since 1980s, overexploitation of groundwater has led to rapid piezometric decline and the uneven thickness of aquifers have induced differential subsidence and fissures.
2 – Xi’an Overpumping the confined groundwater,the differential subsidence, the geomorphology influence of beams and hollows. Since late 1970s, there has been 10 fissure belts due to the groundwater overpumping.Since the 1980s, 8 fissure belts have been studied.
3 – Kechi Baig (Quetta) Excessive exploitation of groundwater and uneven bedrock led to differential subsidence, resulting in earth fissure.
4 – Guangming (Wuxi) to the level piezometric decline; the asymmetrical bedrock lead to differential subsidence and the development of fissures. Around 2000, many fissurres began to emerge in the village and evolved into geological hazards.
5 – Jocotepec
6 – Ciudad Guzma¡n
7 – Tous
8 – Sirijan Uneven distribution of clay layer, excessive extraction of groundwater and decline of groundwater level led to differential subsidence and fissuring. Excessive exploitation of groundwater leads to land subsidence and eventually leads to earth fissure. After the rain erosion, the earth fissure expand.
9 – Freemont Valley (CA)
10 – Chandler Heights (AZ)
11 – Beijing Driven by the original fault zone, excessive pumping of groundwater leads to uneven settlement. Groundwater level was relatively stable from 1965 to 1999,the fissures were in the development stage. Groundwater level continued to decline dramatically from 1999 to 2005, the fissures were in the active stage. After 2005, groungwater level recovered due to water supplement from out of Beijing,the fissures are in the mitigation stage.
12 – Datong Active faults release energy in the form of creep. Excessive exploitation of groundwater, expansion of the depression cone, buried faults at the margin of the funnel become active, resulting in earth fissures. In the early stage of groundwater overly pumping from 1981 to 1984, 3 fissures appeared. From 1985 to 1993, 7 fissures appeared. From 1993 to 2002, 3 fissures appeared.
13 – Qingxu The thickness of upper and lower aquifers in buried faults is uneven, and excessive pumping of groundwater is taken into account, which leads to uneven settlement. Since 1960, the exploitation of confined water has increased year by year, the confined water level dropped sharply.In 1990s, fissures appeared in Jiaocheng fault zone and then the situation became more and more serious.
14 – Lubei Plain (Shandong) Under the influence of the earthquake and excessive pumping of groundwater, there are fissures in the center of the depression cone, and there are goafs because of coal mining. Prior to 1900, many secondary fissures were caused by earthquakes. After 1900, human activities led to fissures, and 2010-2014 were peak times of fissures caused by uman activities.
15 – Huozhou (Shanxi) The groundwater level declined because of goafs. After the formation of goafs, the overburden layer on the coal seam is elevated and gradually bent and fractured, forming a fracture zone. The decline of the groundwater level leads to differential subsidence, resulting in the formation of earth fissure.
16 – Guendalin Valley (Murcia)
17 – Taiyuan Excessive exploitation of groundwater in the confined aquifers results in differential subsidence on both sides of the fault, resulting in earth fissure. There was no fissure before 1970s. From 1970s to 2002, the annual number of new wells increased sharply,water level of confined aquifer dropped,depression cone expanded. After 2002, the water supply was partly from surface water, so that the water level of confined water decreased with lower rate and the earth fissure appeared to be eased from the previous stage.
18 – Xingtai, Shijiazhuang Driven by internal forces from tectonic movement , precipitation and excessive pumping of groundwater leading to uneven settlement. Fissures were caused by the earthquake in 1966 in Xingtai.Since 1970s,over exploitation of groundwater results in differential subsidence and induced activity of earth fissure.
19 – Qishuyan (Changzou) Excessive exploitation of deep groundwater. Buried bedrock ridge created the conditions for differential land subsidence, causing earth fissure. In the middle and late 1970s, fissures began to develop. In 1980s, the economic developed rapidly, excessive exploitation of groundwater led to fast development of earth fissure. Since 2000, Suzhou, Wuxi and Changzhou prohibited to pump underground water, which has eased the situation.
20 – Sarir South Agricultural Project Area Earth fissures were reported in the Sarir South agricultural project as early as 1982. These fissures were mainly caused by lowering of the piezometric heads due to the withdrawal of groundwater. The fissures range in width from 2.5 cm to 100 cm on the surface and, generally, become narrower with depth.
21 – Jinzhong The fault activity is the primary cause of the fissures, meanwhile the earthquake and the groundwater withdrawal are also contributing factors. Since the 1980s,the fissures have been forming along the fault zone because of the frequent seismic activities and expanding with the impact of the groundwater.
22 – Beilou Owing to overexploitation of groundwater and the associated groundwater level decline,the area around the Caohe river has subsided and the fissures have formed along the river channel and kept widening under the fluvial erosion. Since 1965, the groundwater level has experienced sharp decline at least three times due to the decrease of the precipitation. Since the 1980s,the groundwater level as rapidly declined. Meanwhile due to the groundwater overpumping,the area began to subside with the fissures appearing.
23 – Cangzhou Overexploitation of groundwater, hot water and oil and gas resources. Since middle 1960s, the long term of overexploitation has accelerated the land subsidence.
24 – Handan The severe overpumping leads to the differential land subsidence and the appearance of fissures. The fissure first appeared in 1963.The number of fissures kept increasing in the 1980s due to excessive groundwater withdrawal.In late 1990s,especially since 2004, the rate of groundwater level decline decreased as the result of less groundwater pumping.
25 – Hengshui (Heibei Plain) The tectonic activity was related to earthquakes, to which superpose the effects of precipitation, surface water and groundwater pumping. The fissure first appeared in 1963 and rapidly developed after the earthquake in 1966 and 1976. The number of fissures surged in the 1980s due to excessive groundwater withdrawal then kept at a steady level in the 1990s. However, it emerged that the fissures extensively developed after 1998.
26 – Hejian The groundwater withdrawal is the primary cause of the land subsidence. Other secondary factors include precipitation, drought, partial gravity. From 1965 to 1990, the overpumping was becoming a serious problem causing the acute decline of the groudwater level. The presence of fissures and the differential subsidence occured in the blind faults. From 1990s to 2000s, the situation of fissures was alleviated but still dynamic.
27 – Hetang (Jiangyin) The long term overexploitation from deep aquifer. The fissure appeared in 1995 at first and has been active for 12 years. Now it is more stable.
28 – Linfen Structural deformation and consolidation deformation of soil layer caused by the exploitation of groundwater. There have been six zones suffering the fissure hazards. The first zone was found in 1976. From middle 1950s to the 1980s, the land subsidence was continuing at a low rate. However, since the 1980s, the subsidence rate has acutely increased.
29 – Chong’an (Wuxi) The long term of overexploitation of groundwater, the asymmetrical bedrock led to the differential subsidence. The land subsidence was observed in early 1970s and mainly occured in the central urban areas consisting of Su Xi Chang. The villages and towns begun differentially subsided and developed the fissures due to the overpumping. In 2000s, the situation was alleviated as result of the prohibition of pumping groundwater.
30 – Baodi District, Tianjin After extracting the confined water, an horizontal seepage force was produced, with a central compression, edge stretching and the presence of fissures in the edge. After the end of 1979, a huge amount of groundwater was exploited. Then the fissure begun to appear and the development of the fissures reached the peak in 1983 and slowed down to the steady period.
31 – Kashan The long-term overexploitation of groundwater led to the level decline; the asymmetrical bedrock led to differential subsidence and the development of fissures. With overexploitation of groundwater, the land subsidence first occured in 1967 and the fissure first appeared in 1991.
32 – Sunsites (AZ) Overexploitation of groundwater resources and shallow bedrock. Since 1940s, overexploitation of groundwater and shallow bedrock have led to the differential subsidence. The presence of fissures was reported since 1950s. The situation got better after realization of an irrigation canal in 1990s. The rate of piezometric decline increased after stopping groundwater injection.
33 – Mahyar The asymmetrical clay layer and overexploitation of groundwater led to level decline, differential subsidence and the presence of fissures When the underground water level declined, the uneven thickness and alternate distribution of gravel layers and clay layers led to the differential subsidence and the presence of fissures.
34 – Celaya (Guanajuato) Overexploitation of groundwater led to the level decline, with the impact on buried faults, causing differential subsidence and the presence of fissures. Since 1956, the number of pumping wells has raised making the overexploitation of groundwater more severe. The fissure first appeared in 1983 and then extensively developed.
35 – Addis Ababa The deep faults made the associated aquifers uneven; overexploitation of groundwater led differential subsidence and the presence of fissures; precipitation expanded the fissures. Exploitation of groundwater led to the level decline, the conncealed fault induced differential subsidence and the presence of fissures. Then the fissures got expanded caused by the surface run-off.
36 – Yazd-Ardakan Basin Overexploitation of groundwater led to the rapid piezometric decline, with the impact on buried fault, causing differential subsidence and the development of fissures. Over the past 25 years, with the rapid increase of water consumption, the groundwater has been overexploited, and the differential subsidence occurred, resulting in fissures, water shortage in the upper layer and the fissure enlargement.
37 – Al-Negea’ah Overexploitation of groundwater and shallow bedrock led to differential subsidence and fissure development. Since 1980s, overexploitation of groundwater has caused the water level to rapidly decline, with the development of fissures, water shortage in the upper layer and fissure enlargement.
38 – Uttar Pradesh Overexploitation of groundwater led to level decline, differential subsidence and development of fissures. With a significant decrease of precipitation the number of wells rapid increased, overexploitation of groundwater caused fissure appearence soon after a sudden heavy rain in June 2008.
39 – Najran Overexploitation of groundwater led to level decline, differential subsidence and development of fissures.
40 – Casa Grande (AZ) Earth fissures where caused by groundwater withdrawal associated with relief on the buried interface between the alluvial aquifer and the underlying bedrock. Water level began to drop in the 1940s. Fissures started to occur in the middle 1950s and grew untill 1980s.
41 – Las Vegas (NV) Excessive exploitation of groundwater and faulted bedrock led to differential subsidence, resulting in earth fissure. Over the past 80 years, the exploitation of underground water has caused groundwater levels to decline, causing differential subsidence on undulating bedrock, inducing earth fissures.
42 – Chino (CA) Excessive exploitation of groundwater leads to differential subsidence, resulting in earth fissure. Since 1940s, over exploitation of groundwater and the rapidly decline of water level has caused ground fissuers. Peaked in 70s and eased since 90s, as water demand ceased.
43 – Eloy (AZ) Excessive exploitation of groundwater and uneven distribution of aquifers lead to differential settlement, resulting in earth fissure. Since 1920s, earth fissure occurred because of over exploitation of groundwater; in 1960s, the situation of overdraft was serious and the amount of earth fissure increased, and it ceased after 1990s.
44 – Phoenix (AZ) Excessive exploitation of groundwater and the decline of water level led to differential subsidence under the influence of buried faults, resulting in the formation of earth fissure. With the excessive exploitation of groundwater, differential subsidence occurs in buried faults, which results in earth fissure.
45 – Morelia (Michoaca¡n) Under the action of fault zone, the exploitation of groundwater causes the micro-fracture that developed into earth fissures.
46 – Iron County (UT) Long-term excessive exploitation of groundwater and differential land subsidence caused by uneaven bedrock result in earth fissure.
47 – Mashhad Long-term excessive exploitation of groundwater and differential land subsidence caused by uneaven bedrock result in earth fissure. Since 1980, the water demand has increased and the number of pumping wells has increased greatly, which has made the groundwater level drop seriously, and differential settlement has caused the earth fissure.
48 – Marvdasht