Path: bloom-picayune.mit.edu!snorkelwacker.mit.edu!americast.com!americast.com!americast-post Newsgroups: americast.twt.news From: americast-post@AmeriCast.Com Organization: American Cybercasting Approved: americast-post@AmeriCast.com Subject: Quakes on Mars spotted by NASA Date: Sat, 7 Nov 92 19:23:58 EST Message-ID: \SE A;NATION \SS (WS) \HD Quakes on Mars spotted by NASA \BY REUTERS \DT PASADENA, Calif. PASADENA, Calif. (Reuters) - Scientists studying enhanced photographs of the surface of Mars think the red planet may frequently be shaken by powerful tremors, NASA's Jet Propulsion Laboratory said yesterday. The evidence for the "Marsquakes" are the thousands of faults visible in Viking orbiter photographs from the 1970s. Mars is much less seismically active than Earth, but quakes with a magnitude of 6 on the Richter scale probably shake the planet about once every 4 1/2 years, scientist Matthew Golombek said in a paper published in the magazine Science. Magnitude 4 quakes may occur somewhere on the planet about once a month and studies predict two quakes of magnitude 5 or greater shake Mars each year, Mr. Golombek said. "That is a promising prospect for seismological investigation on future missions to Mars," he said. Scientists Bruce Banerdt, David Tralli and Kenneth Tanaka were co-authors of the paper. Mr. Golombek is project scientist for the Mars Environmental Survey project, which would place seismometers on the Martian surface in several missions through 2003 to measure quakes. Seismometers placed on the Martian surface would be able to detect a magnitude 4 quake anywhere on the planet, scientists said. Because Mars is little more than half the size of Earth, a magnitude 6 quake on the planet would have 10 times the effect it would have on Earth, Mr. Golombek said. A magnitude 6 temblor on Earth can cause significant damage. A 1971 earthquake in Los Angeles that measured 6.5 on the Richter scale killed 64 persons. Unlike Earth, where earthquakes occur because of the motion of tectonic plates, the tremors on Mars appear to be from the cooling of the planet, scientists said. Mr. Golombek says evidence suggests Mars was once much more seismically active, but that decreased as the planet's outer crust aged and cooled. This article is copyright 1992 The Washington Times. Redistribution to other sites is not permitted except by arrangement with American Cybercasting Corporation. For more information, send-email to usa@AmeriCast.COM