Lunar noise correlation,imaging and monitoring

Passive seismic techniques have revolutionarised seismology, leading for example to increased resolution in surface wave tomography, to the possibility to monitor changes in the propagation medium, and to many new processing strategies in seismic exploration. Here we review applications of the new techniques to a very particular dataset, namely data from the Apollo 17 lunar network. The special conditions of the lunar noise environment are investigated, illustrating the interplay between the properties of the noise and the ability to reconstruct Green＇s functions. With a dispersion analysis of reconstructed Rayleigh waves new information about the shallow shear velocity structure of the Moon are obtained. Passive image interferometry is used to study the effect of temperature changes in the subsurface on the seismic velocities providing direct observation of a dynamic process in the lunar environment. These applications highlight the potential of passive techniques for terrestrial and planetary seismology.

统计地震学的两个基本定律对应力的依赖关系

统计地震学长期使用的两个幂律关系式为:描述地震频度-震级关系的古登堡-里克特(Gutenberg-Richter)关系式[1]和描绘主震后余震随时间衰减速率特征的大森-宇津(Omori-Utsu)定律[2]。最近,地震频度-震级关系斜率(b值)与断裂模式的相关性研究确定了应力对b值的影响[3]。在此,我们以类似的方式根据主震的断裂模式对余震序列进行研究。我们发现逆冲型主震的幂律余震衰减速率起始前的延时(c值)一般比正断层型地震的短,走滑型地震的c值则处于二者之间。对断裂模式的这些类似依赖关系表明两个基本幂律都受应力状态控制。只有2%的余震有已知震源机制解。因此,c值和b值是两个独立的估算值,它们可作为推断应力场的新方法来使用,目前应力场依然难以直接测定。