Interpretation of the Official Implementation of the "National Standard for the Scope of Earthquake Magnitude"

May 12, 2017, the State Administration of Quality Supervision and the National Standardization Management Commission formally issued a revised mandatory national standards "to seismic regulations" (GB 17740 - 2017). This standard is an important basic technical standards for earthquake disaster mitigation put forward by the China Seismological Bureau, with effect from December 1, 2017 formally implemented.

Magnitude measurement is the most basic basic work of earthquake prevention and disaster reduction technology system. Formulating and implementing strict, accurate, and standardized magnitude standards is of great significance in reasonably determining seismic design measures, scientifically starting emergency response levels, and efficiently and orderly carrying out earthquake relief.

GB 17740 — 2017 “Specifications for Magnitude of Earthquake” is based on the characteristics of wide-band digital seismic records. It fully takes into account the historical continuity of the magnitude measurement and the scientificity of the method, and stipulates the methods and regulations for measuring the magnitude of earthquakes. It is applicable to earthquake monitoring and earthquake emergency. Projects related to seismic magnitude such as information dissemination, scientific popularization, and news reporting are also linked with new earthquake magnitude standards recommended by the International Federation of Seismology and Intra-Earth Physics, which is conducive to carrying out data exchange and scientific and technological exchanges in the field of earthquake prevention and disaster reduction. The revised standard can better adapt to the development needs of China's seismic observation system, and is of great significance in regulating the determination of earthquake magnitudes in China and social applications, and improving the social public service capabilities of earthquake prevention and disaster reduction.

The revised standards include measurement method and the use of both provisions, and GB 17740 - 1999 compared to the main changes are as follows:

( 1 ) Measurement method: The measurement method of the moment magnitude MW is increased , and no change is required between different magnitudes. The local magnitude uses the zoning gauge function to determine the broadband body wave magnitude mB (BB) and broadband surface wave magnitude MS (BB) to facilitate rapid earthquake reports;

( 2 ) Use regulations: For earthquakes with M0 seismic moments , the moment magnitude MW should be selected as the preferred magnitude for external release; for the 4.5 - magnitude earthquake, the broadband surface wave magnitude Μ S (BB) should be selected as the externally issued magnitude; earthquake Forecast (report) should use the measured magnitude.

After the revision, the method for measuring the magnitude was more scientific, the measurement results were more accurate, the measurement speed was faster, and the rules for publishing were more reasonable. The application of the new magnitude national standard will make China the first country in the world to adopt wide-band surface wave magnitude and wide-band body-wave magnitude, which has played a leading and demonstration role in the measurement of magnitude in other countries.

The information in this article comes from the Internet and was reorganized and edited by China Rescue Equipment Network.