The slowly deepening pond of water on the floor of Halema‘uma‘u, the first in recorded history, has captured the interest of media and the public.

The recent appearance of water at the bottom of Halema‘uma‘u, a crater at the summit of Kīlauea Volcano, has attracted wide attention and generated questions.

Everyone agreed that the photos could well show water, but could the green patch be something else?

The lava flow worried residents of Hilo for a time because, after ponding and likely inflating behind Puʻuhuluhulu, it suddenly broke out toward the city at alarming rates of about 2 to 3 kilometers per day (1.5 to 2 miles per day) for nearly a week in late December.

Now, for the first time in over three decades, Kīlauea is not erupting. At the summit of the volcano, earthquake activity is low, and most of the National Park is open for business. No lava is flowing anywhere on Kīlauea, and volcanic air pollution on the island is the lowest it’s been since the early 1980s.

Shortly before midnight on July 5, 1975, Mauna Loa Volcano awakened with a shudder.

HVO notifications include Volcanic Activity Notices (VANs), Status Reports, Volcano Observatory Notices for Aviation (VONAs) and Information Statements.

Rift zones are areas of weakness in the volcano which form early in its lifetime, likely due to spreading of the volcano as it settles.

Interferometric Synthetic Aperture Radar calculates the difference between two radar images acquired by an orbiting satellite taken at different times.

The USGS Hawaiian Volcano Observatory and its partners operate a network of seismic monitoring stations on the Island of Hawai‘i and throughout the state.