Re-determination of deep moonquake sources using the Apollo 17 lunar surface gravimeter
نویسندگان
چکیده
Copyright and Moral Rights for the articles on this site are retained by the individual authors and/or other copyright owners. For more information on Open Research Online's data policy on reuse of materials please consult the policies page. Introduction: The internal structure of the Moon is essential information that infers the origin and evolution of the Moon. Many attempts have been made for its estimation and seismic analysis using the data from the Apollo Passive Seismic Experiment (PSE) is one of the most successful methods carried out. We have been focusing on the possibility of applying the Lunar Surface Gravities (LSG) data of Apollo 17 to seismol-ogical investigation [1]. Through analyses of intensive lunar seismic events called HFTs, we showed that with appropriate data processing, the data can be used in seismic analyses [2]. In this study we focused on deep moonquakes which play important role in estimating the deep inner structure of the Moon. Deep Moonquakes: Sources of deep moonquakes are said to distribute around 1000 km in depth and occur periodically at specific source regions [3]. From the Apollo PSE data set, 7245 deep moonquakes and 166 source regions (excluding source regions that provide data only from a single station) have been reported [4]. By using the LSG as the additional seismic station, source determination with better condition will be possible. With the expanded observation network and data set, more accurate source determination will be expected. In addition, we may locate the deep moonquakes that could not be located with data set of 4 seismic stations. Among the reported deep moon-quakes, 60 source regions did not provide a number of arrival time picks suffient to locate their source and their determination may impose new constraints on lunar seismology. In this study, we try to determine source regions of deep moonquakes of various signals to noise ratio. We compare our result with previous determinations and evaluate the contribution of the LSG data to the seismic analysis of deep moonquakes. Date Selection: As the first step, we examined two source regions that are relatively active and are near the LSG; A06 and A07. We also selected A33 as a typical farside deep moonquake to test the possibility of seismic analysis of farside deep moonquake with the LSG. Finally, we examined unlocated deep moon-quakes. We chose source regions that are reported to be likely on the lunar farside in Nakamura (2005) …
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