What is tsunami warning?

Scientific research and practical experience of tsunami show that tsunami can be predicted. With the help of advanced earthquake monitoring instruments and communication equipment, we have established a tsunami early warning system. It can monitor the generation, spread and development of tsunami in real time, and send out early warning information in time, which has won valuable time for disaster prevention and mitigation and the safety of people's lives and property, and enabled us to plan ahead and face the tsunami disaster calmly. ...

1. International Tsunami Early Warning System

In view of the fact that more than 80% of the world's major earthquakes and tsunamis occurred in the Pacific region, the countries most affected, especially those along the Pacific coast, urgently need to use advanced science and technology to reduce the casualties and economic losses caused by tsunamis. On the basis of American earthquake and tsunami warning system, 1965 established the International Tsunami Warning System (ITWS). The system is an early warning network for tsunami monitoring and forecasting, which consists of three systems: earthquake and tsunami monitoring system, tsunami early warning center and information release system. Among them, the earthquake and tsunami monitoring system mainly includes seismic stations, seismic network centers and ocean tidal stations. At present, 32 member countries (or regions) have joined the international tsunami early warning system, mainly the countries along the Pacific Ocean and the Indian Ocean and some island countries. The main task of the system is to determine the location and magnitude of earthquakes that can produce tsunamis in the Pacific Ocean and its surrounding areas. If the location and magnitude of the earthquake exceed the warning line that a tsunami may occur, it is necessary to issue tsunami warning information to all member States.

Work flow chart of Pacific all-weather tsunami early warning system

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Tsunami knowledge

Who are the member countries (or regions) of the global tsunami early warning system? Australia, Canada, Chile, China, Colombia, Cook Islands, Costa Rica, Korea, Ecuador, El Salvador, Fiji, France, Guatemala, Indonesia, Japan, Malaysia, Mexico, New Zealand, Nicaragua, Panama, Papua New Guinea, Peru, Philippines, North Korea, Russia, Samoa, Singapore, Thailand, Tonga, Tuvalu, United States, Thailand.

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Tsunami story

200 1 65438+February1,PTWC was renamed "Richardo. Hagmeyer Pacific Tsunami Warning Center "to commemorate Richard Hagmeyer, former leader of PTWC. He has been in charge of PTWC for many years and made outstanding contributions to tsunami warning.

Pacific Tsunami Warning Center (provided by PTWC)

2. Pacific Tsunami Warning Center

1960 after the tsunami in Chile, countries along the Pacific coast realized the need to establish a joint tsunami early warning system to reduce the serious harm caused by the tsunami. 1968, with the support of the United Nations, the International Oceanographic Commission (IOC) set up an international government cooperation group, which was responsible for establishing the Pacific tsunami early warning system. The U.S. government provided the Ewa Coast Center in Lu Lu badminton, Hawaii, as the headquarters of the Pacific Tsunami Warning Center (PTWC), and so far. The monitoring scope of PTWC covers the whole Pacific region. Meanwhile, tsunami warning centers have been established in several regions, including Hawaii, Alaska, Japan and Chile. This is the only multinational tsunami warning system in the world. PTWC is not only the operation center of the international tsunami warning system, but also the national tsunami warning center of the United States and the regional tsunami warning center of Hawaii. Its main responsibility is to collect seismic wave and tidal information, exchange information of member countries, evaluate potential earthquake and tsunami risks and issue tsunami warnings through a monitoring system composed of seismic stations and ocean tidal stations distributed in the Pacific region. After the Indian Ocean tsunami in 2004, the monitoring scope of PTWC expanded to the Indian Ocean, South China Sea of China, Caribbean Sea and Puerto Rico &; The United States Virgin Islands, and 24-hour uninterrupted monitoring of the monitoring area.

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Tsunami technology

The establishment of tsunami warning observation points generally considers two factors. First, whether the monitoring instrument is close to the key monitoring geological structure active area in order to accurately monitor seismic wave information; The second is whether the communication with the outside world is fast and convenient, so as to inform the tsunami warning in time. Recently, French researchers have found that the tsunami triggered by the submarine earthquake will generate signals in the atmospheric ionosphere, and the intensity of this signal is closely related to the intensity of the tsunami. Based on this discovery, we can monitor tsunami by satellite in the future, which provides a new idea for strengthening tsunami monitoring and reducing tsunami disasters.

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3. West Coast and Alaska Tsunami Warning Center

1964 After the Alaska earthquake, with the support of the US Coast and Survey, a tsunami observatory was established in Palmer, Alaska, to provide tsunami warning services for the coastal areas of Alaska. 1973, Alaska National Weather Service took over the observation point and renamed it Alaska Tsunami Warning Center. 1996 with the continuous expansion of the monitoring area, the center was named the West Coast and Alaska Tsunami Warning Center (WC/ATWC for short).

At present, the tsunami warning area of the center includes the coastal areas of Canada, Puerto Rico, the British Virgin Islands and all coastal areas of the United States (except Hawaii). At the same time, the center also provides support services for the Pacific Tsunami Warning Center (PTWC). The main duty of the tsunami warning center is to quickly locate, measure and analyze the major earthquakes in the monitoring area, so as to determine whether it is possible to trigger a tsunami, predict the arrival time of the tsunami, and issue a tsunami warning.

West Coast and Alaska Tsunami Warning Center (provided by ATWC WC)

Schematic diagram of the distribution and occurrence age of some earthquakes and tsunamis in the history of China coastal areas

4. China tsunami disaster

Since 2000, there have only been more than ten recorded tsunamis in China, which shows that the tsunami disaster along the coast of China is not very serious. Geographically and geologically, there are three reasons why there are few tsunamis along the coast of China: First, there are few geological structural units such as large fault zones, island arcs, trenches, etc., which are easy to cause submarine earthquakes, and there is a lack of "power" to produce tsunamis; Second, most of China's sea areas are vast continental shelves, which extend far outward and the seabed topography is gentle and open. This marine environment is not conducive to the formation and spread of the tsunami. In China's offshore waters, the average depth of Bohai Sea is about 20 meters, the average depth of Yellow Sea is about 40 meters, and the average depth of East China Sea is about 340 meters. None of them are deep, except the average depth of the South China Sea is1200m. Therefore, the possibility of offshore tsunami caused by earthquakes in most sea areas is relatively small, and it is only possible to produce tsunami when there are major earthquakes in parts of the South China Sea and the East China Sea. Thirdly, the offshore of China is surrounded from north to south by an island arc chain consisting of Kuril Islands, Japanese Islands, Ryukyu Islands, Zhoushan Islands, Taiwan Province Island and South China Sea Islands. They constitute a natural maritime barrier, effectively blocking the invasion of the transoceanic tsunami generated by the Pacific Rim seismic belt. 1960 When the Chilean tsunami struck, the wave height at the mouth of the Yangtze River in China was only 20 cm. Although China's offshore waters do not have the marine conditions for earthquakes and tsunamis, we cannot ignore the prevention of tsunami disasters. Especially in Fujian and Taiwan Province provinces, the potential danger of earthquake and tsunami disasters still exists.

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Tsunami knowledge

China Tsunami Early Warning System: The National Marine Environment Forecasting Center of the State Oceanic Administration is responsible for the tsunami early warning and forecasting business in China, and the tsunami information released mainly includes: the time forecast of tsunami propagation to offshore tide stations, the height forecast of tsunami waves, and the propagation time map of tsunami waves in the ocean. At present, 30-minute warning of transoceanic tsunami, 20-minute warning of regional tsunami and 0/5-minute warning of local tsunami can be realized. In recent years, the State Oceanic Administration has organized and developed the Pacific Tsunami Database, the Pacific Tsunami Propagation Numerical Forecast Model and the Overseas and Offshore Tsunami Numerical Forecast Model. After the Indian Ocean tsunami, the National Marine Environmental Forecasting Center further developed the numerical forecasting model of tsunami propagation in China on the basis of years of tsunami early warning technology research, which played an important role in preventing tsunami disasters.

5. Being abroad before the tsunami

Although tsunami disasters are rare in China, the China government attaches great importance to the prevention of tsunami disasters, and has established corresponding tsunami emergency plans and tsunami early warning systems. At present, there are national and local earthquake monitoring networks in China, and the State Oceanic Administration has established more than 100 marine monitoring stations on islands and offshore, which basically has the tsunami early warning capability. China joined the international tsunami early warning system on 1983, and can share the relevant information provided by this system. However, there is still much room for improvement in tsunami warning in China. First of all, risk assessment should be carried out in coastal tsunami-prone areas as soon as possible, and emergency plans should be formulated. Secondly, because people generally don't know enough about the tsunami disaster, we should popularize the scientific knowledge of tsunami, organize escape drills, and improve the public's awareness and ability of tsunami disaster prevention and avoidance. Third, set up tsunami monitoring buoys to improve tsunami early warning capability. Fourth, establish a timely and rapid tsunami warning and release system.

Tsunami Warning Center Monitoring Room

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Tsunami record

Since the founding of New China, there have been three tsunamis off the coast of China. The first one was1July, 96918th, which was caused by an earthquake of magnitude 7.4 in the central Bohai Sea. The second time was 1992 1.4, which occurred at the southern tip of Hainan Island. The wave height recorded by Yulin Tidal Observatory is 0.78 meters, and a tsunami wave with a wave height of 0.5 to 0.8 meters has also appeared in Sanya Port. The third tsunami occurred in the Taiwan Province Strait in 1994.

6. American Tsunami Warning System

The tsunami warning system in the United States is under the responsibility of the National Oceanic and Atmospheric Administration (NOAA). It consists of two tsunami warning centers, namely Pacific Tsunami Warning Center (PTWC) and West Coast and Alaska Tsunami Warning Center (ATWC). The tsunami warning system in the United States has formed a three-dimensional model of "open space and sea". Ocean satellites in space can monitor the changes of marine environment around the clock, seismic wave detectors deployed on the coast, islands and seabed can monitor submarine earthquakes, and tidal monitoring stations in the ocean can feed back tidal information to the monitoring center at any time. With these "eyes and ears", the tsunami warning center can grasp the occurrence and development of tsunami in the first time. In addition, the United States has established a complete seismic network. The National Earthquake Information Center and the National Seismological Network under the US National Geological Survey can provide data and information of catastrophic earthquakes around the world and play an auxiliary role in the tsunami early warning system.

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Tsunami technology

After the Indian Ocean tsunami in 2004, the United States announced a national tsunami prevention plan. The plan hopes to reduce the tsunami losses in the coastal areas of the country by strengthening the use of submarine earthquake and volcano monitoring systems, deep-sea detection buoys and other high-tech early warning means. The plan includes: conducting tsunami risk assessment in all coastal areas of the United States; Adding tsunami detection buoys, tide gauges and seismic sensors to provide real-time data for computer models to strengthen tsunami prediction and early warning systems; Providing technical assistance to improve the early warning system for tsunami and other disasters in the Indian Ocean; Encourage domestic coastal communities to make tsunami response plans to reduce the damage of future tsunamis.

The United States not only attaches importance to tsunami monitoring and early warning, but also issues tsunami early warning to the public at the first time through various channels. Tsunami warning is mainly released through major TV media and radio stations, and even military communication means are used in emergencies. The U.S. government has made a complete tsunami emergency plan and made a quantitative evaluation of relevant units to ensure the normal operation of the system when the disaster occurs. "Stones from other mountains can attack jade", and the experience of tsunami early warning system construction in the United States is worth learning and using for reference.

Monitoring Scope Map of Pacific Tsunami Warning Center (PTWC) and West Coast and Alaska Tsunami Warning Center (ATWC) (provided by PTWC)

Japan Tsunami Warning Center

7. Tsunami early warning system in Japan

Japan is located in the Pacific Rim seismic belt, and the coastal areas facing the Pacific Ocean are often hit by tsunamis caused by submarine earthquakes. To this end, Japan attaches great importance to tsunami warning and prevention. Japan has established an efficient and rapid tsunami early warning mechanism from the central government to local governments. First of all, there is a central disaster prevention meeting in the cabinet of the highest government agency, presided over by the Prime Minister himself, which is responsible for formulating basic disaster prevention plans and determining basic disaster prevention policies. When a major disaster occurs, the Japanese government will set up an emergency disaster response headquarters within 30 minutes, with the Prime Minister as the minister, to quickly determine the disaster response and direct relevant agencies to immediately put into rescue work. In the construction of tsunami early warning system, Japan has invested 20 million US dollars every year to establish a high-tech automatic monitoring system, which can alert all beaches in China within 3 minutes in case of a strong undersea earthquake. The Japanese government has also built breakwaters and installed alarms in tsunami-prone areas. At the same time, the Japanese government attaches great importance to the application of high technology in tsunami disaster prevention. In 2005, KDDI Company of Japan developed an "automatic broadcast emergency alarm" system, which can release alarm information through mobile phones. In addition, Japan is envisaging the establishment of a complex tsunami prevention system, which can not only warn before the tsunami strikes, but also monitor the waves with cameras and provide shelter for people around. 20 1 1 March11day, a strong earthquake and tsunami occurred in Japan. Despite the heavy losses in this disaster, Japan's tsunami early warning system played an important role and effectively reduced the disaster losses.

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Tsunami warning example

1983 A devastating earthquake and tsunami occurred in the Sea of Japan in May. Seven minutes later, the arrival of tsunami waves was observed at the tidal station closest to the epicenter. 14 minutes later, a tsunami warning was issued to the whole country of Japan, and it was also transmitted to the tsunami defense institutions designated by the governments around the Pacific Ocean. Due to the timely warning, the tsunami only caused 104 deaths, and the economic loss exceeded one million dollars, greatly reducing the harm of the tsunami.

8. Release tsunami warning information

At present, the release of tsunami warning information is mainly handled by Pacific Tsunami Warning Center (PTWC) and West Coast and Alaska Tsunami Warning Center (WC/ATWC). When a submarine earthquake occurs, the early warning center decides whether to carry out tsunami assessment according to the size of the earthquake. Generally, earthquakes below 6.5 will not cause tsunamis. Once the earthquake magnitude is greater than 6.5, the tsunami warning center will immediately monitor the data of tidal stations. If the data shows that a tsunami has formed and may cause disasters, the Tsunami Warning Center will issue a tsunami warning to relevant member countries. This process is very rapid, generally less than 10 minutes. After receiving the early warning, the member States quickly issued a tsunami warning to the people in coastal areas and took corresponding preventive measures. In order to gain more time for disaster relief, we are actively promoting new tsunami warning release methods. This method is called "peer-to-peer" tsunami warning release, that is, tsunami warning does not need to be transmitted step by step, but is sent directly to coastal residents by tsunami warning institutions. At present, the United States, Japan, Indonesia and other countries have established such a rapid warning release system, so that coastal people can get tsunami warning at the first time.

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Tsunami knowledge

Classification of tsunami warning information: According to different tsunami levels, there are different levels of tsunami warning. The highest level is the tsunami warning covering the whole Pacific Ocean, which is issued for the tsunami that can destroy the whole Pacific coast. The warning information is updated every hour until the tsunami warning covering the whole Pacific Ocean is lifted. The second is the regional tsunami warning, which is issued to the areas that can be reached within 6 hours after the tsunami, and updated every hour. The third category is tsunami information announcement. If there is a major earthquake in the Pacific Ocean and its adjacent areas, it is necessary to issue an information bulletin to the member countries of the international tsunami early warning system, and decide whether to issue a tsunami warning according to the situation.

Release tsunami warning information

9. Tsunami prevention also needs the help of "high technology"

In an era when science and technology are the primary productive forces and have a decisive impact on human life and the future, tsunami early warning and disaster relief are also inseparable from the power of science and technology. In recent years, especially after the Indian Ocean tsunami in 2004, countries have generally strengthened scientific research in the tsunami field. At present, the application of science and technology in tsunami early warning and disaster relief is mainly in the following aspects: using advanced computer technology to simulate the occurrence and spread of tsunami and establish tsunami model, thus providing theoretical basis for tsunami early warning system to make accurate and timely prediction; Adopt advanced earthquake and tsunami monitoring equipment, such as tsunami detection buoys, tide gauges, earthquake sensors, etc., to monitor the occurrence and spread of tsunami in real time; Using advanced geographic information system (GIS) technology can help rescuers determine the scope and degree of disasters, guide rescuers to the disaster site, and deliver relief materials to the victims in time. It can be seen that high technology has penetrated into the whole process of tsunami warning and rescue, and played a very important role.

Tsunami warning buoys can monitor undersea earthquakes and play a role in predicting tsunamis and mitigating disasters (photo by Xinhua News Agency)

10. How to assess the tsunami risk?

We all know that magnitude and intensity are used to indicate the magnitude and destructive power of earthquakes, so how can we scientifically measure the magnitude of tsunami damage? At present, Watanabe's tsunami classification method is widely used internationally. Generally, when the tsunami is 1, it constitutes a destructive tsunami and causes certain economic losses; There will be casualties at level 2; Level 3 will be seriously affected; Above level 4 may be a devastating disaster.

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Tsunami technology

Digital simulation of tsunami: At present, an American company has developed a disaster simulation system, which can simulate the occurrence of natural disasters, including tsunami, through three-dimensional animation. The system first simulates the earth sphere, and then simulates the whole process of tsunami caused by submarine earthquake, and the effect is very realistic. The application prospect of the system is also very broad, and it has been welcomed by many museums and science and technology museums. Through systematic demonstration, the audience can intuitively and comprehensively understand the occurrence process and formation principle of tsunami, which also has a very positive role in promoting the development of geological science popularization.

Tsunami classification in Watanabe Fu Wei

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Tsunami story

Honolulu, Hawaii, USA is not only the seat of the state capital, but also the largest city in Hawaii with a population of about 850,000. As Hawaii is a tourist attraction, many tourists come here every year. Hawaii is a port city, bordering on the Pacific Ocean, and is at high risk of being hit by a tsunami. Although the tsunami warning will mean that the whole city is in a state of emergency, even so, for the staff of the Pacific Tsunami Warning Center, once there is an alarm, a tsunami warning will be issued. 1994 when the tsunami struck, the whole city was evacuated, and the real waves were only 20 cm high. Although it was a false alarm, in order to avoid greater losses, tsunami warning information should be released in time.