Number of known moonquakes tripled with discovery in Apollo archive

THE WOODLANDS, TEXAS— The Moon suddenly seems more alive. From 1969 to 1977, seismometers left on the lunar surface by the Apollo astronauts detected thousands of distinctive “moonquakes.” Now, half a century later, a new analysis has cut through the noise in the old data and nearly tripled the number of moonquakes, adding more than 22,000 new quakes to 13,000 previously identified ones. The finding, presented last week here at the Lunar and Planetary Science Conference, shows “that the Moon may be more seismically and tectonically active today than we had thought,” says Jeffrey Andrews-Hanna, a geophysicist at the University of Arizona unaffiliated with the work, which is in review at the Journal of Geophysical Research . “It is incredible that after 50 years we are still finding new surprises in the data.” The Apollo missions placed two kinds of seismometers on the surface: ones capable of capturing the 3D motion of long-period seismic waves, and others that recorded more rapid shaking. All of the previously known moonquakes came from the long-period instrument; the short-period data sets contained so much noise, generated by temperature swings between the lunar days and nights, and errors from the radio transmission of the data, that they were indecipherable to 1980s technology. For decades they sat largely untouched. “Literally no one checked all of the short-period data before,” says Keisuke Onodera, a seis...
Source: ScienceNOW - Category: Science Source Type: news