Introduction
This paper explores both 2008 and 2013 Sichuan earthquakes in China. It provides detailed descriptions of how each earthquake occurred, similarities and differences between the two incidences. In addition, it shows social and economic effects of the two earthquakes on people.
The Sichuan Earthquake in 2008
On May 12, 2008, a devastating earthquake with a magnitude of 7.9 or 8 on the Ritcher scale rocked Sichuan Province of China. The aftermaths were catastrophic and immediate. It killed around “90,000 people and injured nearly 363,000, destroyed more than 15 million homes, left 10 million homeless and 1.5 million displaced, and it caused more than $20 billion in damage” (Hays, 2011, p. 1).
This was the worst and the most devastating earthquake since “the Tangshan earthquake of 1976 in China” (Hays, 2011, p. 1). The 2008 Sichuan earthquake was stronger than the earthquake that hit Kobe, Japan in 1995. Sichuan took approximately 80 seconds. It caused a movement in the ground of about seven meters close to the epicenter.
The quake broke huge mountains and made rivers to alter their course. In addition, it destroyed bridges, buildings, and pavements. The quake erased the entire town and ripped off highways. It cut off all means of communication in the affected areas. Landslides from the quake buried homes as the wave caused thousands of buildings to collapse and topple.
Geological accounts of the 2008 Sichuan Earthquake
Geologists have long established that there is the Longmenshan fault in Sichuan. It ranges between 250 and 300 kilometers with a width of 30 kilometers. They estimated that the quake could have caused a large movement (13 meters) from the fault line. This is a significant movement. The shaking was massive for more than two minutes. Evidence from the bedrock indicated that damages started from the epicenter and progressed in the northeastern direction.
Scientists noted that the catastrophic strength and magnitude could have emanated from the impacts of the two colliding tectonic plates (Hough, 2002, p. 34). The Longmenshan swerved in two places, which had a length of 100 kilometers and a width of 30 kilometer. In addition, other parts sheered for about 150 kilometers in length and 30 kilometers in width.
Sichuan has three major fault lines in which Longmenshan is the next one to Chengdu (Scholz, 1991, p. 12). Chengdu is a city near to the epicenter of the quake. However, Chengdu did not suffer severe damages because it lies “on a stable area basin of Sichuan and massif of Yangtze” (Hays, 2011, p. 1). There were no reported cases of fatalities from Chengdu.
Some scientists noted that a huge dam constructed along the fault line could have played a major role in initiating the earthquake. They noted that the water reservoir could have built the pressure, which caused the quake. Zipingpu Dam’s height is 156 meters. The dam is 550 meters away from the areas of weaknesses and merely 5.5 kilometers far from the epicenter.
Scientists estimated that the weight of the water at the reservoir could have been 315 million tons. This weight was enough to trigger an earthquake or increase its magnitude. Others claimed that Zipingpu dam could have played a role in altering the time or magnitude of the earthquake. Hence, the result was more violent than expected because the dam was close to the fault line.
Most scientists have agreed that such huge dams, which are close to fault lines, can result in tremors. However, other scientists have dismissed the claims that the quake could have originated from the dam. They note that the area of Sichuan lies on an active fault lines. Moreover, the shock was too intensive to result from the dam. Hence, Zipingpu dam was not a major cause of the quake.
Damages of the 2008 Sichuan Earthquake
The earthquake cut off all means of communication. It caused underground infrastructure to rupture and collapse. It claimed thousands of human lives and animals. Moreover, several people sustained serious injuries. Socially, the Sichuan earthquake of 2008 destroyed families and relations.
The direct economic cost from “the earthquake was over $146 billion” (Hays, 2011, p. 1). Sichuan Province incurred more than 91 percent in losses. The estimated value of the lost property during the earthquake was $122.7 billion. After the earthquake, many people became poor because of the lost property.
Although authorities knew that Sichuan was on active fault lines and susceptible to earthquakes, there was no mitigating approaches to subsequent damages or evacuation and rescue strategies in place to respond to the potential earthquake.
Some claimed that there were clear indications from strange behaviors of animals before the quake. For instance, frogs and toads started to migrate in large numbers before the earthquake took place. These were predictors of the impending quake in the region.
The Sichuan Earthquake 2013
The Sichuan earthquake of April 20, 2013 had a magnitude of 6.6 (EQECAT Inc., 2013, p. 1). The quake generated strong waves of up to 50 kilometers away from the epicenter. However, the impact of the quake was strong in the affected area. Shaking continued for about 60 seconds.
Initial reports had indicated that the quake had claimed about “200 fatalities with thousands of injured persons while others were missing” (EQECAT Inc., 2013, p. 1). The number of fatalities could have risen because of the dense population within the region and impacts of the shaking ground.
Immediate areas near the epicenter of the earthquake suffered severe damages. In most cases, damages are severe in Sichuan province because of a high population density. This earthquake mainly affected rural locations of the province. Many farmers lost their crops and livestock mainly around the Tibetan Plateau.
Damages of the 2013 Sichuan Earthquake
Like in the previous earthquake, the region near the epicenter suffered the most damages. Generally, any structures or lives in these areas become extremely vulnerable when shaking takes place. This was also the experience in the 2008 earthquake. While there are some reinforced buildings, many people reside in buildings or structures, which lack reinforcement against earthquakes.
The earthquake left more than 100,000 people without homes and any means of communication. Sichuan is an agricultural zone in China while Chengdu has thrived on manufacturing. As a result, Sichuan has been important to both local and foreign investors. Most commercial centers are near large rivers. These areas have weak grounds, which are prone to movement during shaking.
Thus, the damage to industrial plants and agricultural land were severe. However, the 2013 earthquake did not affect most commercial buildings and industrial plants. Damages from the 2013 earthquake were not widespread relative to the 2008 earthquake.
After the experience of the 2008 earthquake, the Chinese government took some initiatives to “protect its citizens by investing in schools and hospitals” (EQECAT Inc., 2013). It confirmed that no school collapsed in the 2013 Sichuan earthquake. However, there were widespread landslides, which hampered aid efforts and emergency rescue.
Geological explanations
Scientists noted that the quake could have occurred along the fault line on the Longmenshan, which was 12 kilometers in depth. The M7.9 earthquake of 2008 originated from the same fault line of Longmenshan. The tectonics of the Himalaya region and Eurasia plates are responsible for seismically active tectonic plates in the region. These plates converge to create seismically active places (Grotzinger and Jordan, 2010, p. 184).
Conclusion
In both earthquakes of 2008 and 2013, areas near the epicenter experienced the most devastating damages to both lives and properties. Generally, the Longmenshan fault line has been the main source of both the 2008 Sichuan earthquake and the 2013 Sichuan earthquake. The magnitudes of these quakes were different. In addition, impacts differ based on the number of fatalities and damages to property.
Thus, economic and social impacts of both earthquakes are similar, but differ based on the intensity of each quake. On this note, the 2008 Sichuan quake caused the greatest damage than the subsequent one of 2013. In the 2008 earthquake, there were speculations that that the quake could have originated from the large dam next to the epicenter.
However, some scientists warned that the impact was so severe and devastating than what could have originated from the dam. Overall, they concurred that dams do have a role in influencing the time or magnitude of earthquakes. The two colliding tectonic plates have been responsible for the two earthquakes in Sichuan. They release the built up seismic strain that causes damages on the surface of the earth.
References
EQECAT Inc. (2013). M6.6 Quake in China Responsible for 200+ Fatalities. Web.
Grotzinger, J., and Jordan, T. (2010). Understanding Earth (6th ed.). Cranbury, NJ : WH Freeman.
Hays, J. (2011). SICHUAN EARTHQUAKE IN 2008. Web.
Hough, S. (2002). Earthshaking Science: What We Know (and Don’t Know) about Earthquakes. New Jersey: Princeton University Press.
Scholz, C. (1991). The Mechanics of Earthquakes and Faulting. Cambridge: Cambridge University Press.