Quakes show that moon, gradually shrinking, is tectonically active

FILE PHOTO: Astronaut James Irwin, lunar module pilot, gives a military salute while standing beside the U.S. flag during Apollo 15 lunar surface extravehicular activity (EVA) at the Hadley-Apennine landing site on the moon, August 1, 1971. NASA/David Scott/Handout via REUTERS/File Photo

WASHINGTON (Reuters) - The moon may be dynamic and tectonically active like Earth - not the inert world some scientists had believed it to be - based on a new analysis disclosed on Monday of quakes measured by seismometers in operation on the moon from 1969 and 1977.

Researchers examining the seismic data gathered during NASA's Apollo missions traced the location of some of the quakes to step-shaped cliffs called scarps on the lunar surface that formed relatively recently, in geological terms, due to the ongoing subtle shrinking of the moon as its hot interior cools.