Earthquake and disaster reduction knowledge

According to the laws obtained by a large amount of measured materials over the years, when the energy of the earthquake reaches a certain degree, the magnitude saturation phenomenon will occur, that is, as the energy of the seismic waves increases, the corresponding seismic size will not increase. The situation is different. Such as: short -cycle body wave shock MB has saturated after 6.5, the consolidated phenomenon of near -seismic ML after 7.0, the medium -length cycle body wave vaginal MB has saturated after 8.0, the face wave shock MS is after 8.5 after 8.5 Saturated phenomenon.

In order to overcome the earthquake saturation, for huge earthquakes, the world is generally used to determine the magnitude of the earthquake torque, and the magnitude of the earthquake -determined by the earthquake torque becomes a torque magnitude. The earthquake torque is under the theoretical model, and the physical quantity obtained from the analysis of the earthquake spectrum is related to the size of the earthquake. The size is generally calculated through the method of waveform reaction.

According to research, the MS of the large earthquake with a large earthquake with a bursting length of the earthquake is almost similar to that of MW. When the rupture length is longer, their differences will be obvious. It is generally believed that the MS standard is the natural continuation of the MS standard to the destructive earthquake magnitude. Essence

The spectrum earthquake M (T) is a wave -to -level seismic level using different cycles, and the seismic signal with a broadband seismizometer is filtered. The magnitude of the shock level is determined separately for different frequency bands. value.

Domestic international news reports generally use the international universal earthquake -level, the Li's earthquake. The Li's Earthquake is a kind of earthquake -grade labels proposed by two seismicists from California Institute of Technology in the United States and Beno Gutenberg in 1935. The observed seismic wave amplitude and cycle, and considering the attenuation of the seismic wave from the source to the observation point, after a certain formula, the calculated seismic seismic is calculated. Due to the limitations of the "The Scaling Law of Earthquake Spectra" (The Scaling Law of Earthquake Spectra ", the Li's earthquake level will produce the saturation effect of about 8.3 ~ 8.5. By the beginning of the 21st century, earthquake scholars generally use the physical characteristics of the huge earthquake to describe the physical characteristics of the huge earthquake. Essence

The surface wave seismic standard MS is more suitable for determining the magnitude of the shallow earthquake from a distance (more than 1000km in the earthquake), and the results of the surface waves of earthquake institutions in various countries are also consistent. Therefore The wave shock level, the torque level can be used as a useful supplement to the surface of the surface, but it cannot completely replace the surface waves. The most commonly used face waves have saturated problems after 8.6, and the general earthquake generally uses a torque magnitude to express it more reasonable.

At 13:46 on March 11, 2011, Beijing time occurred on a huge earthquake in the waters near the east coast of the Honshu. The USGS of the National Earthquake Network, the Japan Meteorological Agency and the US Geological Exploration Agency gave different earthquake parameters:

China Earthquake Network Measures: At 13:46 on March 11, 2011, Beijing time on the waters near the east coast of Honshu (38.1 ° north latitude, 142.6 ° east longitude), a M8.6 earthquake occurred, and the depth of the earthquake was 20 km. After the earthquake, the data of the Taiwan Network Center used the data of the National Earthquake Network and the Global Earthquake Network to determine the parameters of this earthquake in detail. Based on this, the China Earthquake Network Center determined that the seismic level of this earthquake should be revised to M9.0 as the official result of the public information release.

The measurement parameters of the Japan Meteorological Agency: a magnitude 7.9 earthquake in Northeast Japan (38.03 ° north latitude, 143.15 ° east longitude), the depth of the earthquake is 10km, Tokyo has a strong sense of earthquakes. Alert; on the 11th, the earthquake magnitude was corrected to the 8.8 level of the Ri Shi; on March 13, 2011, the Japan Meteorological Agency revised the Japanese earthquake to the level 9.0 (38.103 ° north latitude, 142.860 ° east longitude), and the depth of the earthquake sources was about approximately about approximately about It is 10 km, the highest earthquake in the history of the Japanese earthquake. (To be continued)

- END -