Carol Ann Johnston, a third-year English Department graduate student was in her Perkins Hall apartment putting in a contact lens early yesterday morning when the mirror began to shake. At the exact same time across campus, Zoe Bercovitch '87 was doing homework in her Hollis bedroom when the walls started trembling.

That was because in the Adirondack Mountains, 85 miles north of Albany, N.Y., at 6:19 a.m., the earth began to quake.

The tremor notched a 5.2 on the Richter scale, a relatively modest earthquake, but it was the largest to shake the Boston area in recent years.

The earthquake was apparently the result of the Adirondack region's slow physical secession from the rest of New York State, according to Joseph Steim, a research assistant in the department of Geological Sciences and a seismologist at Harvard's Oakridge observatory at Harvard, Mass. "The entire region has been undergoing a general uplift for more than a hundred million years," Steim added, explaining that "nonuniform stresses within the region results in fracturing."

Steim said that the earthquake was an isolated one, and did not portend an increase in terranean activity in the future.

The famous San Francisco earthquake of 1906 that killed thousands of people registered an 8.3 on the Richter scale. Yesterday's, in comparison, probably brought no damage because it started in an unpopulated area. Even if it had centered in a major city it would only have caused minor damage to a few chimneys, walls, and tombstones, said John Ebel, a seismologist at an observatory in Weston, Mass.

The last quake to affect Boston came on January 19, 1982, when a 4.6 tremor was centered in Gaza, N.H. Since then, a few tremors have been recorded on seismographic equipment but have escaped public notice.