"It's just relatively safe, because there is no big fault zone passing through the main city.
Relevant personnel of the Municipal Bureau of Earthquake Prevention and Disaster Reduction believe that.
Nevertheless, Kunming people still feel unsafe.
According to the data, Kunming is located on Xiaojiang fault zone and Puduhe fault zone, which belongs to earthquake-prone area and prone area.
Historically, there have been many strong earthquakes around Kunming, and in the middle of the19th century, there was a big earthquake close to 8.0 on the Richter scale.
In recent years, strong earthquake activity in Yunnan has shifted from west to east.
Once the active period of earthquake is started, there will be many earthquakes with magnitude above 6 in the whole province in the next 10 year.
According to the national seismic zoning map, among the four counties (cities) in Kunming/Kloc-0, there are 3 counties (districts) with 9 earthquake fortification and 8 counties (districts) with 7 earthquake intensity, all of which are listed as key earthquake monitoring and defense areas of the country and Yunnan Province, and the earthquake situation is very severe.
So, how big is Kunming currently threatened by earthquakes? According to the monitoring data of the Bureau of Earthquake Prevention and Disaster Reduction, it is unlikely that an earthquake of magnitude 5 or above will occur in Kunming in the near future.
There is no abnormality, and there is generally no strong earthquake.
1On September 6, 833, an earthquake of magnitude 8 occurred in Songming.
One year later, earthquakes occurred in Yuanjiang, Chengjiang and Lunan, and two years later, earthquakes occurred in Yuanjiang and Xinping, all aftershocks of the Songming earthquake.
According to records, before the Songming earthquake, the surrounding meteorological changes were abnormal.
First of all, "the yellow sand covers the sun, and the twilight is unclear, three days and three nights"; It rained for nine days, and the rain was black.
When the earthquake was about to happen, it was dark. After a while, it lit up again, and the earthquake happened.
"There must be something abnormal before the earthquake. Of course, if there is an anomaly, there may not be an earthquake, but there is no anomaly. There are generally no strong earthquakes.
Ping Yuan, deputy researcher of the Municipal Bureau of Earthquake Prevention and Disaster Reduction, said that the so-called "anomalies" are also called earthquake precursors, such as changes in chemical composition of groundwater, water temperature and animal anomalies.
Abnormal phenomenon is one of the contents of earthquake prediction.
Kunming has built the "Kunming Earthquake Monitoring Precursor Digital Network", which is in the forefront in Yunnan and even the whole country.
There are ***33 digital and analog precursory observation items such as water level, water temperature, mercury, helium and electromagnetic wave instruments in the city, which are distributed in ten counties (cities) and districts of Kunming, and record abnormal changes in various places.
Before the Wenchuan earthquake, there was an anomaly in Heilongtan.
Before the Lunar New Year's Eve last year, the muddy water in Black Dragon Pool had been turbid for thousands of years and became clear for several days.
From February 6th to 10, koi fish and other ornamental fish in the pond died one after another, with the number reaching more than 3 tons. What is even more surprising is that two and a half hours before the Wenchuan earthquake, 10,000 koi fish have just been released into the clear water pool, constantly jumping out of the water, and some even jumped very high.
The relevant departments ruled out poisoning and other factors, and finally thought it was caused by geological variation.
Pingyuan believes that this is definitely related to the Wenchuan earthquake. "As long as the earthquake may spread to Kunming, there should be anomalies around it."
According to the recent earthquake monitoring data in Kunming, Xia Pingcheng, deputy director of the Municipal Bureau of Earthquake Prevention and Disaster Reduction, Ping Yuan, deputy researcher, and Chen Jing, director of the monitoring and forecasting department, all believe that "there is little possibility of an earthquake of magnitude 5 or above in Kunming recently."
Two fault zones affect Kunming.
In the neotectonic zoning, Kunming is located in the tertiary neotectonic zone of Kunming sag in the uplift area of Sichuan-Yunnan fault block, which is an important part of the strongly faulted lake basin in eastern Yunnan under the background of regional neotectonic uplift.
Kunming basin is the largest Quaternary inherited fault basin in Yunnan Plateau, which is mainly controlled by the north-south Pudu River Quaternary active faults and influenced by several groups of Quaternary active faults in northeast and northwest directions, forming an extremely complex basin basement shape.
In the division of seismic zones, Kunming is sandwiched between the famous Xiaojiang N-S strong earthquake zone and Yimen N-S medium-strong earthquake zone, which is located in the south-north medium-strong earthquake zone of Pudu River.
In addition, there is a NW-trending Tonghai-Shiping seismic belt in the south. There is a near north-south Tanglang-Yimen moderate-strong seismic belt in the west; There is Xuanwei-Mile seismic belt in the east, which is the transition from strong seismic activity area to weak seismic activity area.
Among them, Xiaojiang fault zone has a great influence on Kunming area, followed by Puduhe moderately strong seismic belt, Tanglang-Yimen moderately strong seismic belt and Tonghai-Shiping seismic belt outside the region.
"The activity level of Xiaojiang fault zone is relatively high, which is famous all over the country, but it is not active in Kunming.
"Chen Jing said that considering that Xiaojiang fault zone is a strong earthquake zone, it directly passes through Dongchuan District and Xundian County, and the seismic fortification intensity is set at 9 degrees, while the general buildings (including villas, multi-storey buildings and high-rise buildings) in other counties (cities) in Kunqu District are fortified at 8 degrees.
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There have been many moderate-strong earthquakes of magnitude 6 or above in the history of the moderate-strong seismic belt composed of Puduhe fault that runs directly through Kunming city, with the largest magnitude of 1985 Luquan earthquake of magnitude 6.3; There have been many earthquakes of magnitude above 7 in the history of the strong earthquake belt composed of Xiaojiang fault zone, the largest of which was the Songming M8 earthquake of 1833, with the epicenter only 30 kilometers away from Kunming city. In the history of the moderate-strong earthquake belt composed of Yimen fault, there have been many moderate-strong earthquakes of magnitude 6 or above, and the largest one is the Wuding earthquake of magnitude 6.5 in 1995.
There has never been a major earthquake in the main city, such as the "safety island"
Yunnan is located at the edge of the collision zone between India and Eurasia, with intense crustal movement and frequent earthquake disasters.
Earthquakes of magnitude 5 or above occur 3 times a year on average; Every two years, earthquakes of magnitude 6~6.9 occur 1 time; Every 8 years, there are 1 earthquake with magnitude above 7.
In 4% of the country's land area, the released earthquake energy accounts for 23% of the country. Since 1970, there have been 8 earthquakes with magnitude above 7, resulting in economic losses of about 800 million yuan.
Data show that in the last century, there were 333 destructive earthquakes of magnitude 5 or above in Yunnan.
Some earthquake researchers have found through long-term research that the earthquake cycle in a certain area of the earth is roughly the same as that of the annular eclipse, which is about 15 to 20 years.
For example, the earthquake of magnitude 6.4 that occurred in Pu 'er before was the one with the highest magnitude and the strongest intensity in this province after the earthquake of magnitude 7 in Lijiang, Yunnan Province in 1996.
Historically, since 1500, there have been more than 5 earthquakes 126 in Yunnan and 2 1 26 in Kunming, but the main city of Kunming has only been affected three times, namely1Guandu 5.3 in 600 and1Guandu 5 in 696.
The main city of Kunming is like a "safe island", which is rarely affected by strong earthquakes.
From 1984, Kunming has instruments for monitoring earthquakes, and the Municipal Bureau of Earthquake Prevention and Disaster Reduction also has statistics. "Generally, there are two felt earthquakes of magnitude 3 to 4 and 20 small earthquakes of magnitude 1 or 2 every year.
But there is no such data, because there are too few earthquakes of magnitude 5 or above.
Kunming is said to be "relatively safe" because there is no major earthquake zone directly passing through it, and there has never been a very strong earthquake in history.
Narrow urban village passages will become the hardest hit areas.
Scientists from Beijing Normal University assessed the risk of earthquake disasters in 30 provincial capitals of China.
The influence of three indicators is mainly considered: the intensity factor leading to the disaster, the vulnerability index of the disaster-bearing body and the coping ability.
Research shows that Kunming ranks 24th among 30 provincial capital cities, ranking 7th from the bottom, higher than Beijing, Shanghai, Chongqing and other cities.
While 40 cities, such as Jiangmen, Huaihua and Artux, whose earthquake risk index (UERDI) is greater than 0.25, are at greater risk. The report suggests that these cities should strengthen their earthquake prevention.
The study explains that although the equivalent magnitude of near-source earthquakes in Haikou, Beijing and other cities is relatively high, the earthquake risk is relatively reduced due to human factors such as the strong seismic capacity of buildings.
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It is understood that 1978, the seismic fortification standard of buildings in the main urban area of Kunming was 7 degrees, and 1989 rose to 8 degrees.
According to experts, the 8-degree seismic fortification standard for buildings in the main urban area of Kunming already belongs to the level of "exceeding the earthquake risk of Kunming".
However, this standard is only aimed at the urban construction of Kunming, and there is no restriction on the housing construction in the village.
Yang Yiyan, an engineer from the Municipal Construction Bureau, believes that even if there is a strong earthquake, it will not have a devastating impact on the buildings in the main city, and the weak point is still in the village in the city.
At present, there are more than 300 villages in Kunming, covering an area of 26.09 million square meters, with a permanent population of 204,000 and a floating population of about 800,000.
According to seismologists, under normal circumstances, two or three-story houses can resist earthquakes of magnitude 5 or above. With each additional story, the seismic capacity of the building will be reduced by 0.4- 1 degree. When it is added to the sixth floor, it basically loses its seismic capacity. In the event of an earthquake, this kind of house is definitely unbearable.
Some experts believe that in the event of an earthquake of magnitude 8 or above (equivalent to earthquake damage of magnitude 6), more than 60% of the houses in the "village in the city" in Kunming will be seriously damaged or collapsed, and the number of casualties and homeless people may exceed 3 1.7 million.
Jin Shucai, director of the Earthquake Prevention and Disaster Reduction Division of the Municipal Bureau of Earthquake Prevention and Disaster Reduction, said that due to historical reasons, there has been no unified planning for villages in Kunming, and the owners are separated by a wall, resulting in narrow passages and no escape routes and shelters.
Once an earthquake happens, it will become a real "earthquake death circle".
As a member of CPPCC, Chen Jing also submitted a report on such issues at the CPPCC meeting last year.
Link: Kunming earthquake history
Since 1500, an earthquake of magnitude 5 or above has occurred in Kunming:
There are five historical earthquakes along the Pudu River fault zone: 1600 Guandu M = 5.3, 1696 Guandu M = 5.8, 1927 Fumin M = 5.3, 1943 Xishan M = 5.0,1.
The Xiaojiang fault zone has 16 historical earthquakes: 1500 Yiliang m 7.8, 1506 Xundian m 5.5, 1560 Yiliang m 5.5, 16 12 Songming m 5.3. 1733 Dongchuan 7.8 August 2 1833 Songming 8, 1927 Xundian 6, 1966 Dongchuan 6.5, 6.2,1985 April 18 Luquan 6.3.
Noun interpretation
Earthquake magnitude: A measure of earthquake magnitude.
Each earthquake has only one magnitude, and the higher the magnitude, the more energy is released.
The magnitude is determined by the energy released by the earthquake. The greater the energy, the greater the amplitude.
The magnitude difference is one level and the energy difference is about 30 times.
1 earthquake of magnitude 6 releases energy equivalent to Hiroshima atomic bomb.
Earthquake intensity: refers to the degree of damage to buildings such as ground and houses caused by earthquakes.
The intensity is different for different areas of the same earthquake.
Close to the earthquake source, the damage is great, the intensity is high, and the opposite intensity is low.