Earthquake Disaster

Earthquake Disaster distribution

Radioactive contamination: third disasters caused by earthquake damage, such as economic impact, social impact (psychological secondary disasters) and human and livestock casualties.

1） Directly disaster

Protogenesis phenomenon of the earthquake, as seismic fault dislocation, and strong ground vibrations caused by seismic waves, which cause losses directly. Mainly the following types.

Ground failure such as ground fracture, ground collapse, ground subsidence, etc. For example, Hainan Island Qiongshan 7.5 earthquake on July 13, 1605, more than 70 villages along the coast near Qiongshan were flooded. Tangshan earthquake in 1976, the whole village of Hangu Fuzhuang in Tianjin sank 2.6m, the deepest up to 3m. The pool water of southern village flowed into the village，water depth can sail a boat, affecting the lives of villagers severely.

Construction and destruction of structures, such as house collapse、 bridge break fall、dam crack、track deformation, etc.

Mountain and destruction of natural objects, such as landslide, landslide, etc. The Peruvian state of anchorage occurred an earthquake of magnitude 7.6 on May 31, 1970, the adjacent Fasca Mountain occurred rockfall as a result of the earthquake, a huge debris flow had formed, at least 18,000 people had been buried by debris flow, as many as 70,000 people died when buildings collapsed in the quake.

Huge waves caused by tsunami and submarine earthquake rushed to the coast, which can cause damage to coastal areas. For example, a major earthquake occurred in the waters near Indonesia on December 6, 2004, it triggered the biggest tsunami in nearly 40 years, leading to the death of more than ten thousand people in the coastal area of India Ocean.

2）Secondary disasters

Secondary disaster means after the occurrence of direct disaster, destroy the original balance and stability of nature or society, thus resulting in disasters. For example, flood caused by river water pouring out and overflow、dam collapse, etc. Inflammable, explosion and highly toxic product and other damaged equipment, induced to inflammable, explosive, and contamination, as well as the spread of bacteria, water pollution and plague, caused losses indirectly. Sometimes secondary disasters cause more casualties and damage than direct disasters. Severe earthquakes can also paralyze some institutions, disorder social order, brought great losses to the country and its people. Major secondary disasters are as follows.

Fire disaster such as, an earthquake of 7.9-magnitude occurred in Kanto, Japan, 1923, just 136 fires in Tokyo, to turn 440 thousand houses into ashes, the death toll of the earthquake reached 143,000, more than 90 percent were killed by fire or asphyxiation of dense smoke.

Floods disaster was caused by dam breaches or landslides clogged up river channels. For example, an earthquake of magnitude 7.5 occurred in Kangding south of China, on June 1, 1786, the landslide dammed the Dadu River, breached 10days later, hundreds of thousands of people died.

Toxic gas leakage is caused by the destruction of buildings or installations.

The plague is caused by serious damage to the living environment after the earthquake.

Characteristics of earthquake disasters

1）Suddenness. Because earthquake prediction is still in the research stage, most earthquakes cannot be predicted, earthquakes often occur unexpectedly. The sudden occurrence of earthquake makes people not only have no organizational and psychological preparation when the earthquake occurs, also difficult to adopt emergency measures such as evacuation. Strong earthquakes can cause massive damage in a short time of seconds or tens of seconds, a serious earthquake can turn a city into ruins instantly. Especially during the night, consequences are even more serious. Such as Tangshan earthquake occurred at 3:42 am, people were in deep sleep at that time, without warning, heavy casualties resulted.

2）Destructiveness. Large earthquakes occurring in densely populated and economically developed areas often result in large numbers of casualties and huge economic losses. According to relevant information: In 1556, 830 thousand people died in the earthquake in Hua County, Shaanxi: In 1737, 300 thousand people died in eastern India earthquake: In 1976, 242 thousand people died in Tangshan earthquake of magnitude 7.8 in China.

3）Wide influencing areas. A major earthquake with a magnitude of 7 or more, can cause thousands of square kilometers to be destroyed, a magnitude 8 earthquake, can cause destruction about tens of thousands of square kilometers or even hundreds of thousands of square kilometers, not only heavy casualties, huge economic losses, seriously affecting people's normal life and economic activities, but also causes great trauma to people's hearts, this kind of wound will not heal in a short time.

4）Multiple. Multiple successive sequences constitute a complex disaster system in time and space, form the multiple effects of destruction in time and space. Seeing from the time, after a major earthquake, over a longer period of time, disaster areas are affected by many other disasters, such as indirect losses or disasters, weather anomalies, etc. Seeing from the space, a strong earthquake, often in a large area, causing a variety of disasters.

5）Secondary (linkage) of destruction. The damage caused by earthquakes can lead to a series of disaster sequences, earthquake disasters under different environmental conditions have different forms and connotations. For example, the destructive effects of mountain earthquakes often lead to landslides, debris flows and other disasters: Plain areas are vulnerable to floods after earthquakes: Coastal cities are vulnerable to tsunamis after the earthquake. In addition, seasons and seasons also affect disaster sequences. For example, winter earthquakes are prone to frostbite and fire, in summer, earthquakes are prone to infectious diseases and floods.

Important factors affecting the degree of earthquake damage

Factors influencing the magnitude of earthquake disasters，mainly from the earthquake itself and the earthquake body two aspects.

1）Earthquake itself. The three elements of earthquake damage are seismic intensity, spectral characteristics and duration, so the earthquake itself mainly refers to the following aspects: magnitude, distance of epicenter, depth, time of earthquake, type of earthquake, etc.

2）Seismic receptor factor. It mainly includes natural environmental factors, artificial environmental factors and social environmental factors. Natural environmental factors include geographical environment, geological environment, site environment and so on: Artificial environment mainly includes residential buildings, industrial buildings, various public facilities, lifeline projects and other artificial buildings: Social environment mainly includes urban and rural areas, and the degree of social civilization, etc. People's knowledge level, fight natural calamities awareness, strain capacity, scientific management level, earthquake region population density, economic development degree, etc.