| The rate of moonquakes seemed to ebb and flow every 27 days, the time it takes the Moon to circle the Earth, suggesting that they were caused by the pull of tidal forces. |
| Instead, seismometers can focus on measuring waves created by moonquakes, tremors created by a variety of sources, including the tidal tug of the Earth. |
| The team also analyzed Apollo lunar seismograms using array processing, techniques that identify and distinguish signal sources of moonquakes and other seismic activity. |
| One reason for crashing the landers was to provide signals for the seismometers the astronauts had placed on the surface to study moonquakes. |
| The Moon is seismically very quiet compared to the Earth, and moonquakes are many orders of magnitude less powerful than typical earthquakes. |
| By measuring where and when gases are vented, scientists hope to determine the frequency of moonquakes and other disturbances. |
