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Haiyuan earthquake in China in December 1920 was the most devastating one in the 20th century, having caused great damage to people’s lives and material goods. The devastating consequences were difficult to estimate, and seismologists have tried to calculate the exact number of victims for many years. Although scientists can explain the origin of earthquakes, they cannot prevent them. This earthquake came into history as a huge fatal tragedy of the Chinese people. Moreover, it was one of the world’s biggest earthquakes. Unfortunately, since that time, there is still no effective relief for such disasters. This paper aims to research the Haiyuan Earthquake to gain a better insight into the issue.
Possible Reasons for an Earthquake
Attempts to explain the causes of earthquakes were made already in antiquity. Nowadays, the causes of earthquakes are easy to explain as science claims that earthquakes happen because of fluctuations in the earth’s crust caused by various reasons (Perdikaris, 2014). Depending on these fluctuations, earthquakes are distinguished into three types: landslide, volcanic, and tectonic. In the case of landslide earthquakes, sometimes, groundwater dissolves rocks, shaping caves and cavities over time, and they often reach a considerable size. Meanwhile, cave roof cannot withstand the pressure reservoirs located above and collapse. As a result, it can lead to an earthquake or even a series of them. According to Vervaeck (2010), earthquakes of this type have a low strength and they are felt only in the immediate vicinity of the epicenter. Furthermore, volcanic eruptions, as quite formidable phenomena of nature, are often accompanied by earthquakes. They are destructive, but their distribution is usually limited to a small area adjacent to the volcano.
Most often, earthquakes are not associated with landslides or volcanic eruptions. So-called tectonic earthquakes refer to the strongest earthquakes, whose area of damage can spread to millions of square kilometers. The reason for such earthquakes is the movement of vast areas of the earth’s crust. Usually, these movements are caused by the fact that the substance in the bowels of the earth moves constantly. The literature suggests that the Haiyuan earthquake in China in December 1920 was exactly that kind of earthquakes (Jolivet et al., 2011). When one portion of the earth’s crust rises and a neighboring one lowers gradually, elastic forces are gradually accumulated and they lead to fracturing. However, these gaps and cracks are not always visible on the surface. Sometimes, they are visible, and in other cases, they are located at a depth of tens of kilometers from the earth’s surface.
Earthquake of 1920 in Haiyuan
Earthquake in Haiyuan that occurred on December 16, 1920 in the Chinese Province of Gansu was one of the most destructive and deadly earthquakes in the world history (Perdikaris, 2014). This province is located in the northwest of China on the Yellow River. The strength of the tremors was about 7.8 on the Richter scale, which led to the destruction of entire cities and villages as well as a considerable damage to such major cities like Lanzhou, Taiyuan, and Xi'an. The fluctuations of this earthquake were recorded even in Norway. The quake was registered at 8 p.m. Beijing time with a magnitude of 7.8 on the Richter scale that was later increased and reached 12.0 on the Mercalli scale. Moreover, aftershocks were observed for three years after the accident. Nowadays, Chinese claim that the magnitude of the Haiyuan Earthquake was 8.5 but they do not specify the scale (Vervaeck, 2010).
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A research conducted by Jolivet et al. (2011) has revealed that before this earthquake, the French Consulate in Chengdu and the British Consulate in Shanghai reported that all clocks stopped there and in many other neighboring cities, chandeliers started swinging, and people even from 1250 kilometers from the epicenter felt seasick. Moreover, the quake affected almost the entire world. The National Geographic magazine described the Hailyuan Earthquake as an extremely abnormal phenomenon, when the mountains began to move, waterfalls turned into landslides, houses, and the huge territory swept into the sea (Perdikaris, 2014). The quake had even more serious casualties because that territory was located in cave soil.
Evidence reported that the vibration lasted for ten minutes and spread for more than 200 thousand kilometers (Perdikaris, 2014). The literature reveals that Haiyuan County situated in Ningxia Hui Autonomous Region was the epicenter of the quake, but the neighboring Gansu and Shaanxi provinces had been affected by the quake as well (Wyss, 2014). It was the largest quake registered in China for the last hundred years with the highest intensity and magnitude. According to Perdikaris (2014), about 70,000 people of Haiyuan County died, which was 1% of the total population of that province. Admittedly, transportation and economic conditions of that time did not allow calculating the total number of victims until 1921 (Jolivet et al., 2011). At first, experts concluded that 230,000 people had lost their lives; however, recently, due to the recent improvements in space-based geodesy, it was calculated that the number of victims reached 270,000 people, which was more than half of the population of that province (Vervaeck, 2010). Centered in Haiyuan, this earthquake affected numerous neighboring provinces.
The earthquakes brought a great distress to people, destroying entire neighborhoods. The consequences were so severe that the affected areas had to develop management plans for the recovery, as it usually happens after the war. As a result, the walls of the houses crumbled, and people died under the rubble of their homes. The supply of water and electricity stopped; roads, buildings, and bridges were destroyed; and there appeared huge cracks on the ground. The recent achievements in geodesy, accompanied by the improved accuracy of deformation measurements, allow scientists to determine the strain and stress evolution and distribution of the seismic cycle. Moreover, postseismic and coseismic deformations can be also well-described, but modelling and measuring spatiotemporal variations remain difficult to determine, and researchers consider this issue a forefront of their work (Wyss, 2014).