Apollo 14 and 16 active seismic experiments, Apollo 17 lunar seismic profiling.

Abstract

Seismic refraction experiments were conducted on the moon by Apollo astronauts during missions 14, 16, and 17. The data indicate that fragmentation and comminution caused by meteoroid impacts has produced a layer of remarkably uniform seismic properties moonwide. Brecciation and high porosity are the probable causes of the very low velocities observed in the lunar regolith. Apollo 17 seismic data revealed that the seismic velocity increases very rapidly with depth. Such a large velocity change is suggestive of compositional and textural changes and is compatible with a model of fractured basaltic flows overlying anorthositic breccias. 'Thermal' moonquakes were also detected at the Apollo 17 site. The source of these quakes could possibly be landsliding.