利用宽频带数字地震资料测定地震震级的方法研究

The method of the measurement of seismic magnitude based on broadband digital waveform

在国际地震学与地球内部物理学联合会(IASPEI)新推荐震级标度在中国地震台网中心应用的基础上,提出中国地震台网地震震级测定方法。研究指出,地方性震级M_L与不同地区的地震波衰减特性具有密切关系,区域性特征明显,为保证中围地方性震级的一致性,宜沿用中国传统测定方法。建议:用IASPEI新推荐的短周期体波震级m_b和宽频带体波震级m_B(BB),分别取代中国传统的短周期体波震级m_b和中长周期体波震级m_B;用IASPEI新推荐的20 s面波震级M_S(20)、宽频带面波震级M_S(BB),分别取代中国传统面波震级M_S7与M_S。为使震级测定规范统一,给出新的震级计算公式和测定方法,并给出新旧震级之间的转换公式。采用新震级标度,可以充分发挥宽频带数字地震资料优势,使中国震级测定与国际接轨。

Based on the application of the new recommended magnitude scale by International Associ ation of Seismology and Physics of the Earth＇s Interior（IASPEI） in China Earthquake Net works Center（CENC）, we have proposed the method of magnitude measurement of China seismic network in this paper. The study indicated that local magnitude ML. has close relation with attenuation of seismic waves in different areas, which has obvious regional characteristic. In order to continue the coherent of our local magnitude, the traditional method is reserved. In order to bring all su periority of broadband digital seismic data into full play and be able to connect with interna tional magnitude measurement, we recommend using new IASPEI short period body wave magnitude mb and broadband body wave magnitude mB（BB） to replace traditional short peri od body wave magnitude mb and medium and long period body wave magnitude roB, and using IASPEI new surface wave magnitude around 20 sMs （20）, broadband surface magnitude Ms（BB） replace our traditional surface wave magnitude Ms7 and Ms. To make magnitude measurement standard unification, this paper gives the computing formulation and measurement method of new magnitude. When the new magnitude scale replaced the traditional ones, there will be difference between the new measurement and the old, the conversion equation was given in this paper.