Volcanic activity at Kilauea continues to feed a pair of lava lakes, one at Puu Oo crater in the east rift zone and another at the summit.

In the middle east rift zone, a lava lake fed continuously by a source beneath the northeast edge remained perched in the center of the crater floor, circulating from northeast to southwest, with breaches and overflows onto the crater floor, according to the U.S. Geological Survey.

Wednesday, the rim of the perched pond was an estimated 16 feet higher than the surrounding crater floor on the east side, which was about 100 feet below the eastern crater rim as of June 29. Both the north and south sides of the perched rim continued to rise slowly above the crater floor through Wednesday morning, suggesting that lava is slowly being injected beneath the rim from the lake itself, the USGS reported.

A tiltmeter on the north flank of Puu Oo cone recorded an abrupt drop of one microradian — a tiny angular measure — about 1 a.m. Wednesday in response to a magnitude-1.9 earthquake north of Puu Oo.

The lava lake at the summit appeared stable with a varied circulation pattern, the agency reported. There was spattering at various locations along the western edge of the lake.

According to the USGS, a ledge has formed within the vent walls. The lake is visible via a keyhole-shaped opening in the ledge.

The only lava erupting from Kilauea’s east rift zone is within Puu Oo crater. However, ground access is restricted by Hawaii Volcanoes National Park and the Kahaualea Natural Area Reserve due to hazardous conditions. Ground and air access to the Halemaumau Crater is also restricted for safety reasons.