In this paper, the original text with references and the tidal combination in March of 20 10 are reprinted, hoping to be helpful to the prevention of aftershocks and related strong earthquakes in Chile.
Tidal combination in March of 20 10: paying attention to the minimum declination angle of the moon
65438+From February 2009 to March 2065438+2000, the interval between the near-earth tide of the moon and the spring tide of the sun and the moon is no more than 3 days, which is a strong tide period, and 20 10 is the last strong tide month. Tidal combinations are as follows:
Tidal combination A: February 28th is the near-earth tide of the moon, and the declination angle of the moon reaches the minimum value of 0.00 107 degrees south latitude on March 28th, which is the spring tide of the sun and the moon, and the tides at the equator and poles change the most, so the oblateness of the earth increases and the rotation slows down, which is beneficial to the formation of La Ni? a phenomenon and can stimulate earthquakes, volcanic activities and cold air activities.
Tidal combination B: March 7th is the last quarter moon, and on the 8th, the declination angle of the moon reaches the maximum of 25.57037 degrees south latitude, and the tidal north-south oscillation amplitude is large, the oblateness of the earth becomes smaller, and the self-conversion is fast.
Tidal combination C: March 12 is the far tide of the moon, March 15 is the moon's declination angle reaches the minimum of 0.00034 degrees south latitude, and June 16 is the spring tide of the sun and the moon. The equatorial and polar tides change greatly, the oblateness of the earth increases and the rotation slows down, which is beneficial to the formation of La Nina phenomenon and can stimulate earthquakes, volcanic activities and cold air activities.
Tidal combination D: On March 22nd, the declination angle of the moon reached a maximum of 25.4205438+0 1 degree north latitude, and on March 23rd, it was the first quarter moon, with a large amplitude, and the oblateness of the earth became smaller and faster.
Tide combination E: March 28th is the near-earth tide of the moon, the declination angle of the moon reaches the minimum value of 0.00002 degrees south latitude on the 29th, and the spring tide of the sun and the moon on the 30th. When the three elements are superimposed, the equatorial and polar tides change the most, the oblateness of the earth increases and the rotation slows down, which is beneficial to the formation of La Nina phenomenon and can stimulate earthquakes, volcanic activities and cold air activities.
March 2 1 day is the vernal equinox, and the sun shines directly on the equator. At this time, the declination angle of the moon is the smallest, which is the spring tide of the sun, the earth and the moon. The tides at the equator and the poles change the most, and the oblateness of the earth increases and the rotation slows down, which is beneficial to the formation of La Nina phenomenon and can stimulate earthquakes, volcanic activities and cold air activities. Therefore, tidal combinations A, C and E deserve special attention. At this time, due to the superposition of solar tides, the influence of the minimum declination angle of the moon on the tides changes. 1960, Chile experienced the largest earthquake swarm in the 20th century.
Xinhuanet Santiago165438+1October 15 The National Emergency Office of Chile reported that according to the monitoring of the National Earthquake Information Center of the United States, two strong aftershocks occurred in the earthquake-stricken area in northern Chile at noon on June 5438+05, with magnitudes of 6.2 and 6.8 respectively. At 12: 03 and 12: 06 local time (23: 03 and 23: 06 on June 5438+05, Beijing time), two strong aftershocks occurred in the second area of northern Chile, the epicentres of which were located 47 km and 46 km northeast of Jones (22 degrees south latitude and 70 degrees west longitude) respectively, with the focal depth.
Xinhuanet Beijing 165438+ 10/6 According to the China Seismological Network, an earthquake occurred in northern Chile (22.9 degrees south latitude and 70. 1 degree west longitude) at 23: 06 Beijing time in 2007. The epicentre is about100km southwest of the epicenter of the Chile earthquake with magnitude 7.9 on June 48+04, 2004 [2].
The strongest earthquake in Chile since 2004 occurred on June 5438+04. According to the US Geological Survey, the earthquake intensity reached 7.7 on the Richter scale and occurred at 12: 40 pm local time (23: 40 Beijing time). The epicenter was located at 170 km northeast of Antofagasta, a port city in northern Chile. South America is one of the regions with frequent earthquakes in the world. The Chile earthquake of 1960 is the strongest earthquake in this area so far-8.5 on the Richter scale. The earthquake in Chile in 2004 was 7.9 on the Richter scale.
On June 5438+065438+1 October1I pointed out that there were three active volcanoes in Indonesia recently, indicating that the ground stress was increasing sharply and was on the eve of eruption. During the strong tidal combination period from June 5438+065438+ 10, we must pay attention to prevent disasters such as earthquakes and volcanoes: 4-5, 10- 13, 17-20, 24-27 [4, 5].
From the autumnal equinox to the winter solstice, the maximum declination angle of the moon can be superimposed with the movement of the solar tidal high tide area from the equator to the tropic of Capricorn, forming the strongest tidal north-south oscillation. 165438+1October 10 is the spring tide of the sun and the moon, corresponding to the moderate-intensity cold air activity from August 8 to 10, the seismic volcanic activity will also be enhanced. 13 is the maximum declination angle of the moon, and the tide oscillates strongly from north to south. Because the tide has been with the sun and the moon for more than 3 days, the superposition effect is not obvious, which will have an impact on the seismic volcanic activity [6]. 165438+124-26 October and 65438+22-24 February, the near-earth tide of the moon, the solar spring tide and the maximum declination angle of the moon are superimposed, and the north-south oscillation of the tide is the strongest; 65438+February 10 The maximum declination angle of the moon is superimposed with the spring tide of the sun and the moon, and the tide oscillates strongly from north to south, so corresponding disasters such as earthquakes, volcanoes and cold air activities should be prevented (see table 1, combinations 4 to 6) [7]. The maximum declination angle of the moon is the main monitoring target in this period. On June 6th 165438, I pointed out that1there were still strong earthquakes from mid-October to February [8, 9].
14 An earthquake measuring 7.7 on the Richter scale occurred in northern Chile, which once again confirmed the strong tide warning of1October 10-13. In view of the superposition of the lunar near-surface tide, lunar spring tide and the maximum declination angle of the moon in1October 24-26 and February 22-24 165438, the north-south oscillation of the tide is the strongest; 65438+February 10 The maximum declination angle of the moon is superimposed with the spring tide of the sun and the moon, and the tide oscillates strongly from north to south, so corresponding disasters such as earthquakes, volcanoes and cold air activities should be prevented (see table 1, combinations 4 to 6) [7]. It is inevitable that strong earthquakes will occur frequently from mid-June, 2007 to the end of February.
1960 at 3 pm on may 2 1, an earthquake of magnitude 8.3 occurred in Chile. From this day to May 30th, this country suffered several earthquakes in succession. During the earthquake, six extinct volcanoes erupted again and three new volcanoes appeared. The 8.5-magnitude earthquake on May 2 1 caused the biggest tsunami in the 20th century. The average height 10 meter, and the maximum height of 25 meters violently attacked the Chilean coast, destroying ports, docks, ships, highways, warehouses and houses. Tsunami waves with a speed of 707 kilometers per hour crossed the Pacific Ocean. When it arrived in Hawaii/0/4 hour after the earthquake, the wave height was still 9 meters. Twenty-two hours later, it reached the Japanese archipelago 17000 km away, with a wave height of 8. 1 m, and all Japanese fishing boats were thrown into the town street. In this earthquake, 654.38+00000 people died or disappeared in Chile, more than 654.38+000000 people's homes were destroyed, and 20% of the country's industrial enterprises were destroyed, resulting in direct economic losses of 550 million US dollars [654.38+00]. 8.5 does not explain the magnitude of the earthquake. If calculated according to the moment magnitude MW, the earthquake should be 9.5.
1960 from may 2/kloc-0 to June 22, the largest earthquake swarm occurred in Chile in the 20th century. In the narrow area of north-south 1400 km, hundreds of earthquakes have occurred continuously, including 3 earthquakes exceeding magnitude 8, 7 earthquakes exceeding magnitude 7 10, and the largest main earthquake is magnitude 8. The earthquake caused tens of thousands of deaths and disappearances, and 2 million people were homeless; The wharf was completely paralyzed, and valdivia was flooded, which caused huge losses to Chile's domestic economy and triggered the largest and most serious earthquake and tsunami in the world [1 1].
May-September of 1960 is a strong tide period, and the near-earth tide of the moon and the spring tide of the sun and the moon do not exceed 3 days. May 1 1- 13 is the superposition of lunar near-earth tide and lunar spring tide, May 14 is the maximum declination angle of the moon, May 20th is the minimum declination angle of the moon, May 25th is the lunar spring tide, May 28th is the maximum declination angle of the moon, and June 9th is-/kloc. May 1 1- 14 (strongest), May 20, May 25-28, June 9-10 (strongest), June 17, June 24 (strongest).
2007165438+1October 17-20,165438+1October 24-27 (the strongest), 65438+February 3, 65438.
Wenchuan
1900 (July 26th, Guangxu period, Qing dynasty) Qionglai earthquake in August, and both Yingjing and Qianwei felt the earthquake. On August 30, 2008 (July 24, 30th year of Guangxu reign of Qing Dynasty), an earthquake of magnitude 7 or above occurred in Daofu, and most houses collapsed within 200 miles along the way. On July 30th, the second day of August, the earthquake struck again. 1905165438+10.8 (October 12th, 31st year of Guangxu reign of Qing dynasty) Zigong earthquake, Yibin earthquake, ten-day aftershock/kloc-0.9 times. Since 1949, there have been three earthquakes of magnitude above 7 in Sichuan: on April 1955, an earthquake of magnitude 7 occurred in Kangding. 1February 6, 973, the magnitude 7.9 Luhuo earthquake affected an area of about 6,000 square kilometers, of which the disaster was serious within 2,000 square kilometers. 1976 August 16, an earthquake of magnitude 7.2 occurred in Songpan.
Wenchuan, Gumao Prefecture, was subordinate to Maowen County (now Maoxian, Lixian and Wenchuan) in the early days of the founding of the People's Republic of China.
Where the population of the Han and Qiang nationalities is mainly. Of course, at present, the most famous place in this place is the giant panda, but in the past, its reputation
The loudest voice is Fan Lihua, a female general. It is said that Xiliang, who is about to get engaged to Xue Dingshan, is from Maozhou. in addition
Outside, it seems that some people think that Yang Guifei is also from Wenchuan, and she is also from A Qiang, which ... I feel a little mysterious. however
The saying that "Wenchuan has been a beautiful woman since ancient times" is probably good, as evidenced by folk songs and online celebrities "immortals"
Sister "can be used as a reference.
Maozhou has a long history of development, such as Maoxian and Wenchuan, which were established as early as the Han Dynasty.
It is managed by the central government, but this place always has a small population and poor economic development.
In my opinion, it may be related to the frequent occurrence of local earthquake disasters.
This area is really an earthquake-prone area. According to records, there have been many strong earthquakes in Maozhou since the Ming and Qing Dynasties.
Twenty times (including four times in Wenchuan County, including 1480, 15 10, 1607, 1657), with a magnitude of 7.5.
The last earthquake, the latest one happened in 1933.
The epicenter of the Maozhou earthquake on August 26th at 2 pm 1933 is located in Diexi Town, north of Maoxian County, so it is also called "Maozhou earthquake".
Diexi earthquake "Its strength is 7.5, and its strength is 10. The damage scope includes Maoxian, Lixian, Wenchuan and Heishui, which are connected together.
Also affected.
Looking at the news telegram at that time, I described the scene as: "Black smoke, dark sky, only thunder in my ear."
, such as rapid fire ... ",and the notes of the local gentry are like this:" At noon, the newspaper suddenly reported from far to near.
Like the roar of thousands of Ma Benteng, people stood unsteadily, fell down along the road, crawled, or supported each other, and lined up.
The house collapsed ... the scene was that four mountains were full of smoke, dust and fog were empty, the sky was dark, few people were there, and the earthquake rumbled on.
In my ears ... it is said that the volcano has erupted and the end of our generation has come. Being awake is very real ... after more than a minute, they calmed down a little.
People can stand and walk, and the sun and mountains are slightly distinguishable, which is the sound of the wall collapsing and the constant cry for help.
Everyone feels that their intestines are cracked and there is nothing they can do ... "
The story of ordinary people may be more vivid-it is about a peddler who buys oil carrying a burden and rushing forward vigorously.
After that, the oil basket was still on the road, but people fell into the cracks and disappeared; It is said that there is a child herding sheep in Hexi Mountain.
When the earth shook, the little shepherd flew to the east of the river, but the sheep stayed in Hexi; He also said that there was a monk in the temple.
After singing, I heard something and ran out of the gate to see it. Suddenly I found that the steps at my feet rose automatically to meet him, so I shouted.
I'm scared to death ...
Diexi Town and Longchi Village suffered the most in this earthquake. These two platforms, about 500 meters above the Minjiang River, were instantly destroyed.
Fell into the river. Only one man and one woman escaped from Diexi Town, and no one lived in Longchi Village. Affected by aftershocks, some huts are
Sneak into the river at night, and the lights in some houses are still on, flashing on the water like dragon eyes.
So local rumors spread everywhere: "The Dragon King appeared!"
According to records, the death toll of Diexi earthquake is more than 6,900, which is inaccurate. Because it's only from Maoxian county
The death toll, at that time, even 300 people died in Chengdu, 200 kilometers away. Lixian, Wenchuan, Heishui and Songpan have none.
There may be no casualties.
At that time, the county magistrate of Maoxian was Zhang Xueyan, who later joined the NLD and launched the Deng Xihou Uprising in 49.
After liberation, he served as deputy director of the Sichuan Provincial Department of Justice. Relatively speaking, Zhang Xueyan is more reliable as a county magistrate.
Is more loyal to their duties, at least after the earthquake, he also visited the Diexi site once (although it is already
Many weeks later), the disaster situation was also counted. Although all his casualties were lucky to escape from the mountains.
After all, what the victim heard was much better than nothing.
eucalyptus
Ganzi-Yushu fault strikes NW-NW, showing a wave-like steep dip. Most of them are distributed in Tibetan pastoral areas on the plateau, and some of them are no man's land, with a total length of about 500km. The fault is sinistral strike-slip, with the strike-slip rate of about 8mm/a in the northwest and middle sections and about 10mm/a in the southeast section. This fault and Xianshuihe fault are staggered in the left sequence near Ganzi, and together with Xianshuihe fault form the southern boundary of Bayankala block (the northern boundary of this block is the East Kunlun fault zone and the eastern boundary is the Longmenshan fault zone. At the same time, faults, Xianshui River, Anning River and Xiaojiang fault zone together constitute the northern boundary of Kangdian rhombic block). The destructive earthquake recorded in historical writing is very incomplete. In the last 200 years, there have been three officially recorded strong earthquakes: Yushu, Qinghai1738 65438+February 23rd and its northwest 6 1/2 earthquake, Luoxu, shiqu county, Sichuan to Yushu, Qinghai, and Yushu1March 29th, 979 earthquake. Department of Earthquake Prevention and Disaster Reduction, Seismological Bureau of China, 1999), all occurred in the northwest section of the fault. The earthquake also occurred in the northwest section. However, there are no strong earthquakes and major earthquake events recorded by official historical figures (including Tibetan and Chinese) in the middle and southeast sections. However, ancient earthquake events with magnitude greater than 7 have been revealed.
History and modern strong earthquake activity characteristics of the northwest section of 1) fault
① 1896 Sichuan Deng Ke Earthquake.
1896 In March, a strong earthquake occurred in Luo Xu, shiqu county (formerly Deng Ke County), Sichuan. The parameters given in the current earthquake catalogue are level 7, epicenter intensity VII, epicenter location (N32.5, E98) and accuracy level 3 (≤50km).
The historical record of this earthquake comes from the local chronicles of Deng Ke County, and the record is limited to the damage near Deng Ke. The main message is "… Deng Ke suddenly had an earthquake, and temples and houses of Confucius Temple collapsed …"; "... Chunke Tusi (on the other side of Jinsha River in Deng Ke, belonging to Tibet) ... the whole family was crushed to death". In addition, at the beginning of the 20th century, Cha Qian, then Deng Ke, wrote Notes on Border Customs in 1908, which recorded: "Chunke Temple, located on the south bank of Jinsha River, was six miles away from Dunke ... Ten years ago, collapsed towers and temples were everywhere during the Deng Ke earthquake ...".
According to the on-the-spot verification made by Sichuan Seismological Bureau when it visited Deng Ke in the early 1980s, during the 1896 earthquake, a large number of landslides and landslides occurred in Seufa, about 30 kilometers northwest of Deng Ke. The largest landslide is along the Jinsha River, which is more than 80 meters high and 300 meters wide, and once blocked the Jinsha River for ten days (Wen Xueze et al., 1985). 1At the beginning of 990, the site investigation team of the West Route Project of South-to-North Water Diversion and experts Zhou Rongjun and Cai Changxing from Sichuan Seismological Bureau visited the earthquake again, and learned that the earthquake damage was not limited to Deng Ke in Sichuan and Chunke in Tibet, but that the earthquake disasters and human and animal casualties in Batang, Benda, Dangtuo, Bayin, Dajie, Sunla and Sewu in Yushu County, Qinghai Province were more serious than those in Deng Ke. It is further found that the surface fracture zone of the 1896 earthquake is distributed near Batang from Dengke to Yushu along Ganzi-Yushu fault (see figure 3.2. 1), with a visible length of about 50km and an estimated extension length of at least 60 km (figure 3.2.5, left). The development scale of the surface fracture zone of this earthquake is the largest in Tuodang area, which is mainly manifested in the slopes, alluvial fans, the latest fracture zone and small fault ridges along the Jinsha River. The shape of cracks and turf uplift in this zone is still very clear, and the fracture is mainly left-handed horizontal dislocation. The maximum observed left-lateral displacement is 5m and the vertical displacement is between 0.3- 1.5m (Zhou Rongjun et al., 2000). According to the empirical relationship between magnitude and surface rupture length, it is estimated that the surface wave magnitude of 1896 earthquake is 7.5 (Zhou Rongjun et al., 2000) and the moment magnitude is 7.3 (Wen Xueze et al., 2003), and the surface wave magnitude (7) given in the current catalogue of historical strong earthquakes in China is likely to be small.