Research Of Energy Magnitude Determination And Application

Seismic energy ES is a characteristic quantity about source quantification.The determination of seismic energy is an important basic problem in the study of seismic quantification,and it is also an important research topic in digital seismology.It plays an important role in promoting the study of seismic quantification and engineering seismology.Seismic energy is a very valuable physical quantity for deep study of an earthquake.In the era of simulated seismic records,it is very difficult to determine seismic energy because of the single frequency band of data.The predecessors can only estimate seismic energy by the empirical relationship between magnitude and seismic energy.The development of broadband digital seismic technology makes it possible to directly measure seismic energy.At present,however,only USGS in the United States produces daily seismic energy ES and energy magnitude Me.Di Giacomo of the German Research Center for Geosciences(GFZ)has improved the method of USGS in the United States and established a new formula for calculating radiation energy.The research proves that the radiation pattern has little influence on the determination results of radiation energy.The main work of this paper consists of the following four aspects.(1)Based on energy magnitude theory and attenuation characteristics of seismic waves,a one-dimensional earth medium model is established and Green's function is calculated.The method of determining seismic energy ES by using broadband seismic waveform data is studied by using the P-wave waveform data of wide-band teleseismic in the range of 20-98 degrees epicenter distance.The Green's function is calculated by using reference earth model AK135 Q and Professor Wang Rongjiang's QSSP software package.The software system for determining seismic energy ES and energy magnitude Me is optimized.The software system is suitable for different focal mechanisms and does not need to modify the results with different focal mechanism solutions,so it can greatly reduce the response time of measuring radiation energy and energy magnitude.The results of measuring the energy ES and the energy magnitude Me of a large number of earthquakes show that the software system runs steadily and the results are reliable.(2)Using the broadband digital seismic data of China Seismic Network and Global Seismic Network(GSN),the seismic energy ES and energy magnitude Me of 110 earthquakes in 2014-2018 were measured and compared with the results of USGS in the United States.Because the biggest difference between the method in this paper and USGS method is that the method in this paper has not been modified according to the focal mechanism solution,the examples are classified according to the focal mechanism in the process of comparison.When the focal mechanism is strike-slip fault,the two magnitude scales fit well,while the focal mechanism is normal fault and reverse fault,the calculation results in this paper are slightly larger than those in USGS,which is consistent with Giacomo's research.Generally speaking,for more than 88% of earthquakes,the difference between the two magnitude scales is less than ±0.35,which verifies the accuracy of the program.Then,combined with the data of the National Oceanic and Atmospheric Administration(NOAA),the characteristics of tsunami earthquakes are briefly analyzed,and the possible effect of energy magnitude theory in tsunami warning is introduced.(3)This paper attempts to apply the theory of energy magnitude to the monitoring of underground nuclear explosion.Previous empirical formulas of surface wave magnitude,body wave magnitude and radiation energy are used to determine the radiation energy and explosion equivalent of nuclear explosion.Artificial blasting can also produce broadband teleseismic P-wave waveform.It is feasible to directly measure radiation energy by using this method.The data preprocessing steps need to be adjusted slightly.In this paper,the radiation energy ES of nuclear explosion in the sixth nuclear test of Democratic People's Republic of Korea is measured to be 5.75?1013J,and the energy magnitude Me is 6.24,the equivalent is about 14 Kt.(4)This paper also compares some valuable earthquake examples and explores some practical applications of seismic energy ES and energy magnitude Me.For example,combining surface wave magnitude,moment magnitude and rupture duration,the potential damage ability of earthquakes and tsunami warning are analyzed.The analysis results of surface wave magnitude MS,moment magnitude MW and energy magnitude Me of several earthquakes show that moment magnitude MW is closely related to the static tectonic effects such as fault length,fault width and average dislocation of source rupture caused by earthquakes,while energy magnitude Me reflects the dynamic characteristics of the source and is closely related to the source kinetics characteristics.Since the energy radiated by seismic waveform is mainly concentrated near the corner frequency of the source spectrum,the energy magnitude Me is more suitable for describing the destructiveness of earthquakes.Joint determination of surface wave magnitude MS,moment magnitude MW and energy magnitude Me plays an important role in earthquake quantitative research and earthquake disaster or risk assessment.In summary,seismic energy ES and energy magnitude Me have different characteristics from surface wave magnitude MS and moment magnitude MW,which can reflect the potential destructive capacity of earthquakes,and is helpful for depth and quantitative analysis of an earthquake.At present,it is difficult to determine the energy magnitude in the world.Only USGS in the United States actually produces the energy magnitude.Now this paper has basically realized: as long as reliable broadband seismic waveform data are available,energy magnitude can be determined quickly and relatively accurately.This creates favorable conditions for the daily output of energy magnitude in the future.