A shocking alarm sounded at the Palmer Observatory in Alaska, USA. On that day, the world's major news organizations announced the disaster news to the whole world-Hawaiian Seismological Station announced that an earthquake of magnitude 8. 1 occurred in China, with its epicenter near Beijing!
According to the US Geological Survey, an earthquake of magnitude 8.2 occurred near Tianjin, about 100 miles southeast of Beijing, with 39.6 degrees north latitude and11degree east longitude.
The Royal Observatory announced that an earthquake of magnitude 8 occurred in China, with the epicenter at 39.6 degrees north latitude and east longitude11.1degree, which is very close to Tangshan.
Central weather bureau, Taiwan Province Province, said: An earthquake of magnitude 8 occurred in the northern part of the mainland, with the epicenter located at135km east of Beiping.
At 4: 30am, China State Seismological Bureau has received earthquake emergency reports from 10 stations in Nanjing, Lanzhou and Kunming, among which 6 stations have given magnitude, but the data are quite different, some are higher than 8 and some are lower than 7. As for the epicenter, there is only a rough estimate near Beijing.
Six in the morning. China Telecommunications Bureau reported that among the contacts with all parts of the country, only the telephone communication in Tangshan area was interrupted, and several calls were made, but there was no reply.
1On July 28th, 976, China Xinhua News Agency broadcast the following news to the whole world: At 3: 42 on July 28th, a strong earthquake struck Tangshan-Fengnan area in the east of Hebei Province, China. Tianjin and Beijing also have strong earthquakes. According to China Seismological Network, the magnitude of the earthquake was 7.5 ... A few days later, China announced the approved earthquake magnitude again: 7.8 on the Richter scale.
Aftershocks of Tangshan earthquake
1After July 28th, 976, the aftershock of Tangshan earthquake continued, and an earthquake with magnitude of 7. 1 occurred in Luanxian on that day 18:45. On may 28th, 2065438 10: 22, an earthquake of magnitude 4.8 occurred at the junction of Tangshan city and Luanxian county. Experts call it the normal aftershock activity of Tangshan earthquake more than 30 years ago.
More than 30 years ago, earthquakes and aftershocks have not been eliminated. Is this possible? The answer is yes.
During the period of1811-1812, the New Madrid earthquake occurred in the New Madrid seismic belt in the south and midwest of the United States. So far, the activity in this seismic belt is still active, and the law of seismic activity conforms to an important law of aftershocks-Omori's Law, so the earthquake in this area is still the aftershock of the New Madrid earthquake.
Aftershocks are earthquakes that occur after the main shock, and their magnitude is smaller than that of the main shock. Aftershocks may occur at any time after a major earthquake, most of which are micro-earthquakes that human beings can't feel, but there are also large earthquakes with great destructive power, which are usually called ghosts after the earthquake, because aftershocks are difficult to predict, and it is easy to cause heavy losses to people and property.
Scientists have found that the intensity and frequency of aftershocks usually follow three laws:
The first is Omori's law. 1894, Japanese scientist Ji Fang proposed in his paper that the longer the time after the main earthquake, the lower the frequency of aftershocks. In 196 1, Yu Jindezhi revised the mathematical formula of Omori's law and improved its accuracy.
Follow Bert's law. It is pointed out that the magnitude difference between the main earthquake and the largest aftershock is an almost constant value with the range of 1. 1 ~ 1.2.
The third is Gutenberg-Richter Law. It points out that there is a correlation between the magnitude of the main earthquake and the number of aftershocks in a given time.