An earthquake swarm near Hawaii's Kilauea volcano has slowed to fewer than 10 small tremors an hour from 100 per hour Sunday morning, according to a Hawaiian Volcano Observatory report.

National Park Service rangers opened the 11-mile Crater Rim Road and summit trails in Hawaii Volcanoes National Park Monday, said Mardie Lane, a spokeswoman for the park. The 18-mile Chain of Craters Road remains closed, and the visitors center is open, she said in a telephone interview.

The earthquakes, which data indicate are being caused by magma moving underground, are occurring mostly between Pauahi and Makaopuhi craters near the volcano's East Rift Zone, the observatory reported on its Web site. At least 10 of the quakes Sunday morning were magnitude 3.0 or stronger.

"She seems to be calming down," Lane said. "It's a very young volcano. We've had ongoing eruptions for 25 years."

A crew from the observatory, which is run by the U.S. Geological Survey, is scheduled to survey the area Monday, according to a report on its Web site.

"The summit is continuing to deflate, but that is slowing as well," Jim Kauahikaua, scientist-in-charge of the observatory, said in a telephone interview. "We think it may mean magma is sort of readjusting itself."

Measurements show steady deflation of Kilauea's summit and a wider rift zone to the east near the Makaopuhi crater, according to the observatory. Kilauea is one of five volcanoes that make up the island of Hawaii, known as the Big Island.

Jan. 3 will mark the anniversary of 25 years of continuous eruptions on Kilauea, Lane noted.

"Knowing this volcano, she's so mischievous she'll probably shut down," Lane said.