The interior structures of planets are attracting more and more detailed attention;these studies could be of great value in improving our understanding of the early evolution of Earth. Seismological investigations of ...The interior structures of planets are attracting more and more detailed attention;these studies could be of great value in improving our understanding of the early evolution of Earth. Seismological investigations of planet interiors rely primarily on seismic waves excited by seismic events. Since tectonic activities are much weaker on other planets, e.g. Mars, the magnitudes of their seismic events are much smaller than those on Earth. It is therefore a challenge to detect seismic events on planets using such conventional techniques as short-time average/long-time average (STA/LTA) triggers. In pursuit of an effective and robust scheme to detect smallmagnitude events on Mars in the near future, we have taken Apollo lunar seismic observations as an example of weak-activity data and developed an event-detection scheme. The scheme reported here is actually a two-step processing approach: the first step involves a despike filter to remove large-amplitude impulses arising from large temperature variations;the second step employs a matched filter to unmask the seismic signals from a weak event hidden in the ambient and scattering noise. The proposed scheme has been used successfully to detect a moonquake that was not in the known moonquake catalogue, demonstrating that the two-step strategy is a feasible method for detecting seismic events on planets. Our scheme will provide a powerful tool for seismic data analysis of the Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) mission, and China’s future lunar missions.展开更多
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 pro...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.展开更多
基金Support from the Youth Innovation Promotion Association CAS (2017094)sponsored by National Natural Science Foundation of China (grant no. 41720104006 and 41774060)
文摘The interior structures of planets are attracting more and more detailed attention;these studies could be of great value in improving our understanding of the early evolution of Earth. Seismological investigations of planet interiors rely primarily on seismic waves excited by seismic events. Since tectonic activities are much weaker on other planets, e.g. Mars, the magnitudes of their seismic events are much smaller than those on Earth. It is therefore a challenge to detect seismic events on planets using such conventional techniques as short-time average/long-time average (STA/LTA) triggers. In pursuit of an effective and robust scheme to detect smallmagnitude events on Mars in the near future, we have taken Apollo lunar seismic observations as an example of weak-activity data and developed an event-detection scheme. The scheme reported here is actually a two-step processing approach: the first step involves a despike filter to remove large-amplitude impulses arising from large temperature variations;the second step employs a matched filter to unmask the seismic signals from a weak event hidden in the ambient and scattering noise. The proposed scheme has been used successfully to detect a moonquake that was not in the known moonquake catalogue, demonstrating that the two-step strategy is a feasible method for detecting seismic events on planets. Our scheme will provide a powerful tool for seismic data analysis of the Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) mission, and China’s future lunar missions.
文摘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.
