When the Luding 6.8 earthquake occurred, some residents in Sichuan and Chongqing received earthquake warning information in advance on their mobile phones. One of the early warning screenshots from Chongqing netizens screened the major websites. "After 64 seconds, the earthquake shear wave arrived in Jiangbei District of Chongqing, and the epicenter was Luding, Sichuan. The early warning magnitude was 6.9, and the earthquake was strong." For a time, topics such as "Is the earthquake warning function of your mobile phone turned on?" and "It only takes 10 seconds to teach you how to turn on the earthquake warning of your mobile phone" were quickly filled with hot searches.
What is earthquake warning? How to realize earthquake early warning function by mobile phone? On September 7th, Wang Gang, professor of Sichuan University, director of Sichuan Key Laboratory of Earthquake Early Warning and Multi-hazard Early Warning Application Information Technology, and director of Chengdu Institute of High-tech Disaster Reduction made an interpretation.
"Early warning" is not "forecast". This function has been built into many domestic mobile phones.
"Earthquake warning is often confused with earthquake prediction, but the difference between words is a thousand miles." Wang Gang said that earthquake prediction is to predict the magnitude, time and place of future earthquakes through research and analysis before they occur. Earthquake early warning refers to issuing an alarm several seconds or dozens of seconds in advance after the earthquake, but before the destructive seismic wave reaches the target area.
How does the mobile phone realize the earthquake early warning function? Wang Gang said that in the early stage, Chengdu Institute of High-tech Disaster Reduction had intensively installed earthquake warning monitors in the earthquake area. When an earthquake occurred in the epicenter, the monitors used the principle that electromagnetic waves were faster than seismic waves, and quickly evaluated the earthquake parameters by acquiring and analyzing the data of earthquake warning monitoring stations distributed in various places in real time. If a major earthquake was found, the people around the epicenter would be given an early warning in time. "For users who have not been affected, the system can pop up windows and give an alarm through mobile phones a few seconds to dozens of seconds in advance. He said.
"During the Luding earthquake of magnitude 6.8, the continental earthquake early warning network jointly built by Chengdu Institute of High-tech Disaster Reduction and China Seismological Bureau successfully issued an earthquake early warning." Wang Wei introduced that at present, many domestic mobile phones such as Xiaomi, Huawei, OPPO and vivo have been connected to the earthquake early warning function. The access of mobile phone operating system to earthquake warning can enable mobile phone users to enjoy earthquake warning function without installing earthquake warning App, which solves the problem that it is difficult for people to download disaster warning App specially at ordinary times. "Mobile phone operating system-level access can also make earthquake warning information be transmitted according to the highest priority and minimize communication delay." Wang Wei said.
Smaller blind area, faster response, future mobile phone or earthquake monitoring base station
Wang Gang said that since 2010, Chengdu Institute of High-tech Disaster Reduction has jointly established a continental earthquake early warning network covering 2.4 million square kilometers with emergency departments and earthquake departments, and has successfully warned 73 destructive earthquakes, including the Lushan earthquake of magnitude 7 in Sichuan in 2013 and the Jiuzhaigou earthquake of magnitude 7 in 2017.
At present, the second-generation continental earthquake early warning network is used in the system, which has shorter response time, higher reliability, wider coverage, denser stations and wider service area, and the coverage rate of the population in Sichuan earthquake area has reached 99%.
"The second-generation earthquake early warning technology has comprehensively upgraded the front-end early warning station, the mid-end transmission response channel and the terminal processing system based on distributed processing. The algorithm is further optimized through the cloud computing operation center, and the system response speed can be improved by using 5G communication technology." Wang Gang said that the second-generation early warning network has reduced the radius of early warning blind area by 15%, and it is expected to have a smaller radius of blind area in some areas, and the false alarm rate and false trigger rate will also decrease simultaneously.
In order to further reduce the early warning blind area and improve the early warning efficiency, Chengdu Institute of High-tech Disaster Reduction is currently testing the earthquake monitoring and early warning function of mobile phones in domestic mobile phone enterprises in order to build a mobile phone earthquake monitoring and early warning network. Wang Gang told reporters that its principle is similar to the traditional earthquake early warning network, but it has achieved the goal of replacing the traditional early warning monitor with the built-in sensor of the mobile phone.
"The acceleration sensor built into the smart phone can sense vibration. Once the mobile phone detects earthquake information, it will send information to the early warning center server. The early warning center server will determine whether an earthquake has occurred in combination with many mobile phone information, and measure the earthquake warning magnitude, epicenter location and earthquake occurrence time in seconds after determination, and send early warning information to the affected people around the epicenter. " Wang Gang said that in the future, it is expected that "where there are people, there will be earthquake early warning capabilities".
Wang Gang said that Chengdu Institute of High-tech Disaster Reduction is laying out the "days — Empty — Land — Underground integrated monitoring and early warning technology will be devoted to providing three-dimensional disaster monitoring information, serving the safety of natural disasters and the decision-making of the government and emergency management departments.