Earthquake alarm, earthquake prediction is not
After the earthquake, there are longitudinal wave (P-wave) and shear (S-wave) seismic waves propagate simultaneously two major outward from the source. Longitudinal wave propagation speed, about 6 km / s, but the shock is relatively small. Shear velocity is slow, about 4 km / s, carrying energy, is caused by the destruction of a major earthquake culprit. Earthquake alert system after the use of the epicenter near the monitoring equipment to capture the seismic P-wave, rapid estimation of seismic parameters and predict the impact of earthquakes on the surrounding area, ahead of the destructive shear waves before they reach the epicenter of the surrounding area, through electronic communications systems Posted predict earthquakes intensity and arrival time alarm information so that relevant agencies and the public to take urgent measures to reduce disaster losses and casualties.
Earthquake prediction, before the earthquake, the earthquake occurrence time, location and intensity (commonly known as the three elements of earthquake) forecast report. Currently humans can not accurately predict earthquakes, earthquake alerts and it is completely different.
In principle there is an earthquake alert blind
Earthquake alert technology itself, in principle, there is an unavoidable blind spot in the earthquake alarm alert blind is essentially no effect, because people in the blind receive an alert message, seismic waves have passed! Indeed alarm technology is very complex, more often than not a seismic station we can accurately judge the need for a sufficient density seismic network. Only the initial few seconds of seismic waves to determine whether the earthquake, is still immature. So that the processing time will be longer, alert blind will be greater.
Key P-wave rapid determination of earthquake alerts
Seismic technology is the most critical alerts quickly determine seismic technology, which is a very complex technology, its complex for two reasons, first, the need after receiving a seismic signal in seismic stations, "immediately" judgment earthquake, preferably a two seconds. This is extremely difficult because of the rapid processing of a conventional seismic (earthquake quick report called) requires a seismic network, throughout the complete record seismic waves and swept after seismic network, a complete data processing. The biggest problem here is the identification of the seismic movement phases, namely the use of computers, the fastest also take a few minutes to determine the seismic parameters, and sometimes errors. This process is completely reliable method to determine the seismic wave propagation principle. However, this method for seismic alert is of no use.
Earthquake alert blind may actually be the largest regional earthquake damage
The length of the rupture zone of earthquake magnitude and is, in general, 5 earthquake is 1-3km, 6 level of 10-20km, 7 level of 30-80km, 8 level of 100-240km, 9 level of 300-1000km. According to the above analysis, if an earthquake alert blind is 20km, it means that blind spot diameter of 40km, which may be the equivalent length of 7 earthquake rupture zone, in general, is the largest regional intensity, which is the largest possible area affected. Visible earthquake alert for large earthquakes than the earthquake damage is blind can function, and the limited effect on the intensity of the strongest earthquake damage areas. At the same time we can see a small earthquake earthquake alert for little earthquake damage for more than more than 7 earthquake blind areas have mitigation action, generally speaking earthquake alarm can reduce the earthquake disaster is not critical. For the most serious direct damage to the earthquake areas may be no effect.
Intensity earthquake alert for abnormal areas and the role of secondary disasters and lifeline facilities
Earthquake alert for earthquake damage mitigation action is limited, but all must have a major earthquake must pay attention to two phenomena, one regional seismic intensity anomalies, such as Tianjin Ninghe earthquake of Tangshan. Second, all the earthquake will inevitably lead to secondary disasters, such as landslides huge Wenchuan earthquake. Of course, the intensity of the abnormal area is often at a distance from the epicenter area. So the earthquake emergency alert for these disasters is still a considerable role. Even within the seismic alert blind, it should also play a role. Further earthquake alert for emergency handling lifeline facilities also have a role, even in an earthquake alert blind, obtained when the earthquake alarm seismic waves have reached in the past, but for the emergency treatment of water and electricity this lifeline facilities or have a significant role, since the earthquake an alarm signal is issued after the earthquake a few seconds or ten seconds, it is the fastest seismic alarms, lifeline facilities for urgent disposal, to avoid further secondary disasters produce water and electricity have a significant role.
Earthquake alert system should quickly identify and alert lifted
Given the state of technology of seismic alert, we can not earthquake alert "demanding perfection." Japan Meteorological Agency in 2007 October 1 Posted earthquake alert system in use made it clear that due to the technical problems of seismic alert itself seismic stations and the environment, including other vibration interference, lightning interference, equipment failure, earthquake determination technology complex seismic alert may appear leak, wrong, wrong situation reported. So for confirmation and the lifting of the earthquake alert is very important and should become an important part of the earthquake warning system.
Earthquake Alert is a complex project and the need to mobilize the whole society to participate
To build an effective earthquake warning system requires the following conditions: First, high-density seismic network: one every 20-30 km (in fact should do 10 km a station - the author note); the second is good processing system: the use of seismic network to capture information quickly locate, calculate third is to improve the distribution system: the alarm information rapidly transmitted to the television, radio, mobile phones, internet and other public Fourth, improve laws and regulations to protect: the whole the system can operate effectively. In a nutshell is the "test to get", "set too accurate", "come to pass", "good use."
Baidu know without a daily newspaper written permission, any units and individuals shall not in any way or reason to know that Baidu content published daily use, copy, modify, copied, transmitted, or bundled with other products use, sale. Where the infringement of intellectual property Baidu know daily, it will pursue its legal responsibility according to the law. Application for authorization and commercial cooperation please contact zhidaoribao@baidu.com
Article Source: Baidu know daily (http://zhidao.baidu.com/daily)
Original link: http: //zhidao.baidu.com/daily/view id = 4274?