For example, the Tsunami Centers will calculate a preliminary magnitude and location for an event as soon as sufficient data is available to make an estimate.

The earthquake, which occurred at 1:42 a.m., had a preliminary magnitude of 2.6, making it a minor quake.

But since the true albedo is unknown and it has a preliminary absolute magnitude of 4.2, it could easily be from about 380 to 860 km in diameter.

The geophysics center at the University of Washington reported the preliminary magnitude of the quake registered 4.8 on the Richter scale.

The quake had a preliminary magnitude of 5.0 on the Richter scale that measures the severity of earthquakes, the center said.

The preliminary magnitude was measured as 4.8 to 4.9 by two different groups, making its explosive force equal to anywhere from 8,000 to 17,000 tons of high explosive.

Dr. Wallace said the blast had a preliminary magnitude of 4.3, equal to about 1,000 tons of high explosive.

The quake's preliminary magnitude was estimated at 5.2 on the Richter scale by the California Institute of Technology in Pasadena.

The quake had a preliminary magnitude of 7.2 on the Richter scale.

The first quake, which happened at 9:43 a.m. has a preliminary magnitude of 4.8 with its centre in the Braeside, Ontario region.