In Santiago, the quake reached 5.0 on the six-point Mercalli scale and lasted 45 minutes, according to the Interior Ministry's national emergencies office.

The US Geological Survey gave an amplitude of 6.1 Moment Magnitude at 2.06 pm (1806 GMT) at a depth of 45.6 kilometers with the epicenter 150 kilometers south of Coquimbo, 195 km north of Valparaiso, and 245 km north by northwest of Santiago.

The open-ended Moment Magnitude scale, now used by US seismologists, measures the area of the fault that ruptured and the total energy released.

A measurement of five indicates a moderate earthquake, six or higher a strong quake, seven a major quake and eight a great quake.

"I usually try to set my expectations a little low and be pleasantly surprised," Arnold, a Wichita native, said in a phone interview Thursday from the farm near Greensburg.

Arnold has created a lot of interest in his discovery. Scientists from The Houston Museum of Natural Science and NASA's Johnson Space Center in Houston are in Kansas to look at the object using a ground-penetrating radar device.

Carolyn Sumners, director of astronomy at the museum, said no one has tried to hype the potentially large meteorite. Only a few news outlets have been notified.

"We don't want another Capone's vault," Sumners said, referring to the 1986 buildup to the live television opening of gangster Al Capone's vault. Only dirt and some empty liquor bottles were discovered.

Sumners wants to do a film for the museum on the recovery of a meteorite and then put the rock on display.

Even if the large object is not a meteorite, several much smaller but potentially significant meteorites could be on the site, according to Arnold's metal detector.

Arnold made big news last fall when on the same farm he uncovered a 1,400-pound pallasite meteorite, the largest of its type ever found. It had a rare bullet-like shape and smooth surface, and was made of nickel and olivine crystals.

The size of that one was not close to the world-record Hoba meteorite, which is about 9 feet by 9 feet and weighs 66 tons. Found in 1920, it is in Namibia.

If the object Arnold found is a meteorite, it could be twice as big as the Hoba meteorite, said Phil Mani, Arnold's partner and lawyer, who will be at the farm site this weekend.

Mani said 99 of 100 objects the metal detector picks up are "meteor-wrongs," but he was still hopeful the Kansas one was a meteorite because of its size. If it is detected as an apparent meteorite, a hole will be dug Monday so that part of it can be uncovered and viewed.

That, Mani said, would be "the eureka moment."

Imaging scientists see a structure in the outer part of the D ring that looks like a series of bright ringlets with a regularly spaced interval of about 30 kilometers (19 miles). An observation made by NASA's Hubble Space Telescope in 1995 also saw a periodic structure in the outer D ring, but its interval was then 60 kilometers (37 miles). Unlike many features in the ring system that have not changed over the last few decades, the interval of this pattern has been decreasing over time.

These findings are being presented today at the Division for Planetary Sciences Meeting of the American Astronomical Society held in Pasadena, Calif. Images are available at http://www.nasa.gov/cassini , http://saturn.jpl.nasa.gov and http://ciclops.org .

"This structure in the D ring reminds us that Saturn's rings are not eternal, but instead are active, dynamical systems, which can change and evolve," said Dr. Matt Hedman, Cassini imaging team associate at Cornell University, Ithaca, N.Y.

When Cassini researchers viewed the D ring along a line of sight nearly parallel to the ringplane, they observed a pattern of brightness reversals: a part of the ring that appears bright on the far side of the rings appeared dark on the near side of the rings, and vice versa.

This phenomenon would occur if the region contains a sheet of fine material that is vertically corrugated, like a tin roof. In this case, variations in brightness would correspond to changing slopes in the rippled ring material.

Both the changes over time and the "corrugated" structure of this region could be explained by a collision of a comet or meteoroid into the D ring, which then kicked out a cloud of fine particles. This cloud might have inherited some of the tilt of the colliding object's path as it slammed into the rings. An alternate explanation could be that the object struck an already inclined moonlet, shattering it to bits and leaving its debris in an inclined orbit.

In either case, the researchers speculate the aftermath of such a collision would be a ring slightly tilted relative to Saturn's equatorial plane. Over a period of time, as the inclined orbits of the ring particles evolve, this flat sheet of material would become a corrugated spiral that appears to wind up like a spring over time, which is what was observed.

Based on observations between 1995 and 2006, scientists reconstructed a timeline and estimated that the collision occurred in 1984.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team is based at the Space Science Institute, Boulder, Colo.