Early alerts help save lives in quake-prone areas

Standards

Early warning of earthquakes is a highly sensitive topic, and sometimes mistakes have led to chaotic scenes.

On Aug 8, 2013, the Japan Meteorological Agency, which is responsible for releasing earthquake information nationwide, issued a warning that a magnitude 7.8 quake would hit Nara prefecture, Honshu Island.

However, a magnitude 2.3 quake occurred in nearby Wakayama prefecture instead, triggering widespread panic among local people. The mistake not only underscored the need for technical improvements, but also related legislation.

"Fujian is the first province in China to establish detailed rules and standards for earthquake early warnings, including regulations related to the main body of information release, trigger conditions and legal liability," said Guo Hao, director of the FJEA's executive office.

The agency's efforts mean that Fujian is at the forefront of the nation's early warning program, and even the blue-and-white color scheme used on the exteriors of monitoring stations was pioneered by the FJEA.

In addition to improvements in early warning technology and legislation, more detailed data about the Earth's crust is needed to further develop the system and support infrastructure improvements in earthquake-prone regions.

However, seismic waves that reflect the state of the Earth's crust only occur during earthquakes, so, instead of waiting for the next temblor, seismologists produce "artificial quakes" to trigger waves and collect data without causing injury or damage.

Meanwhile, one project－a landsea joint survey－has become an important program that is promoted by earthquake-prone countries.

While 80 percent of earthquakes in China occur under the sea, most of the nation's quake and crust monitoring is conducted on land, so the ability to predict submarine temblors is underdeveloped. That has placed great emphasis on the landsea joint survey, which focuses on the structure of the deep crust in Fujian and the Taiwan Straits, to support research into early warnings of oceanic earthquakes.

In 2013, the FJEA independently designed and developed China's first shipborne air gun seismic source system, which provided a great boost for the joint survey.

After the gun has been dropped into the water and triggers vibration waves, seismologists receive and analyze the frequency of the waves, either on the ship or on land. The resultant data is gradually filling blank spaces in research related to the structure of the Earth's crust around the Taiwan Straits.

In Norse mythology, people believed that earthquakes were caused by the writhing of Loki, a god who had been poisoned by a rival. Now, we not only understand the vibration principle of earthquakes but also use science and technology to "fight" natural calamities.

Training and practice

Studies have shown that with training and practice on seismic prediction, earthquake-stricken areas can reduce casualty numbers by 14 percent if a warning is given 3 seconds in advance.

If the warning is received 10 seconds before, the figure rises to 39 percent, while 20 seconds see the number of casualties fall by 64 percent.

Recalling the Nantou earthquake, Fan said: "People should know what to do, and where to hide when an earthquake is imminent. Generally speaking, the only people who can save you are yourself and the person next to you－therefore, improving individual protection and awareness of how to help yourself are always the simplest, most realistic survival methods.