1950 At 22: 09: 34 on August, a strong earthquake of magnitude 8.5 occurred in Chayu County, Tibet, China (28.5 degrees north latitude and 96.0 degrees east longitude). The epicenter intensity of the earthquake was 65438 02 degrees, and nearly 4000 people were killed. The strong earthquake made the seismographs all over the world offline. American scientists believe that the earthquake occurred in Japan, while Japanese scientists believe that the earthquake occurred in the United States. Hundreds of thousands of square kilometers of Himalayas are instantly unrecognizable: the Yarlung Zangbo River was cut into four sections in the landslide; The whole village was thrown across the river. Hundreds of lamas and nuns were buried under the ruins of the temple. A British tea grower in India said that the earthquake "sounded like a high-speed train passing through a tunnel".
1966 Xingtai earthquake
Xingtai earthquake consists of two major earthquakes:15: 29 on March 8, 1966, Longyao County, Xingtai District, Hebei Province 14 seconds (37 degrees 2 1 minute north latitude, 1 14 degrees 55 minutes east longitude), and a magnitude 6.8 earthquake occurred. 1March 22, 966 16: 08, a 7.2-magnitude earthquake occurred in Ningjin County, Xingtai District, Hebei Province (37 degrees 32 minutes north latitude,1/5 degrees 03 minutes east longitude), with the epicenter intensity of 10 degrees. Two earthquakes * * * killed 8064 people and injured 38000 people, resulting in economic losses 1 100 million yuan. This is a big earthquake after a long drought. After the earthquake, it snowed all over the sky. Premier Zhou Enlai visited the earthquake-stricken areas three times, and the sufferings of the people made him cry. He instructed China to establish its own earthquake early warning system. The cause of earthquake prediction in China is an epoch-making milestone in Xingtai earthquake.
1970 Tonghai earthquake
65438+65438 0970+1:00: 3410.5, a 7.7-magnitude earthquake occurred in Tonghai County, Yunnan Province, China (24.0 degrees north latitude, 0.02.7 degrees east longitude). In this earthquake, the epicenter intensity was 10 degree, the focal depth was 10 km, 1562 1 people were killed and 3243 1 people were disabled. It is the second serious disaster with more than 10,000 deaths in China since the 1949 Yangtze River flood.
The terrain and geological conditions in this area are very complicated, with basins, mountains and valleys appearing alternately. Fault structures are criss-crossed, among which NW-trending and NE-trending faults are the most serious, followed by NS-trending and EW-trending faults. The earthquake occurred on the Qujiang fault in the northwest. The intensity distribution of Tonghai earthquake is closely related to the location of Qujiang fault. The general trend is that the closer to Qujiang fault, the higher the intensity and the heavier the earthquake damage. The polar seismic belt is distributed in the Qujiang River Valley in a northwest narrow strip along the Qujiang fault, with a long axis of about 52 kilometers.
After the earthquake, many ground fissures were distributed along the Qujiang fault, starting from the north of Miaobei Mountain in Jianshui County, passing through Gaoda in Tonghai County, Shuichetian in Eshan County, Dahaiqi and Niubaidian, reaching the foot of Eshan Mountain, with a total length of nearly 60 kilometers, forming a huge ground fissure zone. Among them, the main ground fissures are not limited by any terrain, crossing ditches and mountains, breaking bedrock for several kilometers, and the widest point can reach about 20 meters, with the right-handed horizontal dislocation nature, and the maximum horizontal dislocation is 2.2 meters.
In addition to the ground fissures densely distributed along the Qujiang Valley, there are many landslides in the earthquake zone, and some areas have subsidence or uplift. Dozens of landslides have occurred in Qujiang Valley, blocking rivers and destroying roads. In addition, sand blasting is also common. Single water jet sand holes and beaded holes appear in groups, and the overall strike is northwest, which is consistent with the strike of Qujiang fault. At that time, the national earthquake work conference was in full swing, and a strong earthquake suddenly came. When the earthquake happened, all the houses in the village were destroyed, and the ground in the earthquake area cracked or subsided. On New Year's Eve, Premier Zhou Enlai called on young earthquake prediction workers to overcome the difficult problem of earthquake prediction.
1975 Haicheng earthquake
1February 4, 975 19: 36: 6, a magnitude 7.3 earthquake occurred in Haicheng county, Liaoning province, China (40 degrees 39 minutes north latitude, 65,438 degrees 48 minutes east longitude). The epicentre intensity of this earthquake was 9 degrees, with 1328 deaths and 4292 serious injuries. The economic loss is 8 1 100 million yuan.
The earthquake zone covers an area of 760 square kilometers. The earthquake occurred in densely populated and industrially developed areas, and it was the largest earthquake in the history of this area. Due to the earthquake warning issued by the earthquake department in China, the local government took effective earthquake prevention measures in time, which greatly reduced the earthquake disaster. Except buildings and other engineering structures were damaged and lost to varying degrees, most people evacuated their houses in the earthquake, and the casualties were greatly reduced. The total number of casualties was 29,579, accounting for 0.32% of the total population, of which 204 1 person died, accounting for 0.02% of the total population. Most of the casualties are old, weak, sick and disabled children and people who don't listen to instructions.
The earthquake caused about 5 million square meters of urban houses to collapse, 6,543,800 square meters of public facilities to be damaged, 6,543,800 square meters of rural houses to be damaged, 2,937 urban and rural transportation and water conservancy facilities to be damaged, and all kinds of equipment and materials suffered serious losses, totaling about 8,654,380+million yuan. The diameter of the ground sand blasting hole is 2.5 meters. There is an earthquake fault zone with a length of about 5.5 kilometers and a crack width of 40 meters. The damaged area of Yingkou City accounts for 3. 1% of the total area of the city.
After the earthquake, disaster relief work was carried out in time. The People's Liberation Army dispatched more than 35,000 people,165,438+073 vehicles and 12 aircraft to participate in the disaster relief. The number of medical teams sent to the disaster area reached 10 1, with 3480 personnel. Water supply repair two days after the earthquake; On February 7, all the disaster areas resumed power supply. The victims spent the Spring Festival in a "three-proof" simple room. A month later, transportation and industrial and agricultural production basically resumed. The success of Haicheng earthquake prediction has achieved great social and economic benefits.
It is speculated that if there is no early warning, the casualties will reach about 65.438+0.5 million, and the economic loss will exceed 5 billion yuan. Because the earthquake was successfully predicted and prevented, it avoided more huge and heavy losses, so it was called a miracle in the history of earth science and world science and technology in the 20th century.
1976 Tangshan earthquake
1At 3: 42: 54.2 on July 28th, 976, a 7.8-magnitude earthquake occurred in Tangshan City, Hebei Province, China (the epicenter latitude was 39.4 degrees, and the east longitude was 1 18.0 degrees). The earthquake, the epicenter intensity 1 1 degree, the focal depth 1 1 km, killed 242,000 people and seriously injured160,000 people. A heavy industrial city was destroyed, with a direct economic loss of10 billion yuan, making it the biggest earthquake in the world in the 20th century.
The earthquake zone extends in all directions with Tangshan as the center, about 47 square kilometers. Most of the old areas in Tangshan are old-fashioned bungalows, which turned into rubble after the earthquake; Most of the new urban areas are multi-storey buildings with brick-concrete structure, which almost collapsed; High-rise buildings with reinforced concrete frame structures have not been spared. The railway track is twisted into a serpentine or wavy shape due to the subsidence of subgrade, which leads to wide cracks on the surface and the collapse of bridges. The earthquake tectonic fracture extends to 8 kilometers, and the ground movement around the fracture zone is amazing, and some people are even thrown into the air within 200 meters on both sides.
The area affected by the earthquake is very large. Strong earthquakes spread to a large area in eastern China, starting from Manzhouli in Heilongjiang in the north, drifting river in Henan in the south, Bohai Bay in the east and Shizuishan in Ningxia in the west. Hundreds of millions of people living in 65,438+04 provinces, municipalities and autonomous regions and more than 2 million square kilometers of land were affected. The damaged area of the earthquake is about 2 1 10,000 square kilometers, of which the severely damaged area is more than 30,000 square kilometers. A large number of houses collapsed in this area, farmland was silted, canals and wells were blocked, and roads, railways and bridges were damaged. According to the Beijing-Tianjin-Tangshan area, the earthquake killed more than 242,000 people, seriously injured164,000 people, and suffered countless minor injuries.
1988 Lancang and Gengma earthquakes
198811:031October 6 1: 06, Lancang, China (22.9 degrees north latitude, 100. 1 degree east longitude). The two earthquakes, which were120km apart, were only 13 minutes apart. Two county towns were razed to the ground, 4 105 people were injured and 743 people died, resulting in economic losses of 25 1 1 100 million yuan.
Earthquakes cause ground fissures, landslides and landslides. The width of the ground fissure is 4~5 meters, and the longest is several kilometers. Landslides block rivers and form dammed lakes, which can be seen in many places. Road surface bulge, crack or subgrade damage. 10 km national defense highway pavement was buried by rolling stones, covering passing vehicles and pedestrians.
Looking back on history, China is in an earthquake-prone area. We should master the necessary common sense of earthquake prevention and self-help after the earthquake while providing earthquake relief and rebuilding our homes ... to minimize casualties and losses, come on, China! ! ! Come on Wenchuan! ! !