(Reuters) – Another small explosion at the summit of Hawaii’s Kilauea Volcano shot more ash high into the atmosphere, putting communities in the southern part of the Big Island at risk, the U.S. Geological Survey (USGS) said.

The volcano, which has been erupting since early May, has sent occasional columns of ash and volcanic gas into the atmosphere at between 10,000 (3,050 meters) and 30,000 feet (9,145 meters) above sea level, it said.

On Sunday, another explosion spewed ash from the volcano, creating a driving hazard for roads on parts of the Big Island.

A fissure in the volcano spewed molten rock 160 feet (49 meters) on Tuesday, slightly lower than the 180 feet (55 meters) it reached from Saturday night into Sunday, pushing a steady flow of lava into the ocean, the USGS said.

A representative for the Hawaii Emergency Management Agency did not immediately respond to a request for comment.

The eruption, which entered its 40th day on Tuesday, stands as the most destructive in the United States since at least the violent 1980 eruption of Mount St. Helens in Washington state that reduced hundreds of square miles to wasteland and killed nearly 60 people, according to geologist Scott Rowland, a volcanologist at the University of Hawaii at Manoa.

The Hawaii eruption has caused no casualties, but lava flows have swallowed about 600 homes since May 3, Hawaii County Mayor Harry Kim said last week.

Vacationland, a private development believed to comprise about 160 homes, was completely erased, and at least 330 houses were devoured by lava at Kapoho Beach Lots, Kim said.

On Saturday, hundreds of construction workers and volunteers, including officials from the Hawaii National Guard and the Hawaii Regional Council of Carpenters, began building 20 temporary housing units in Pahoa for families forced from their homes.

(Reporting by Gina Cherelus in New York; Editing by Bill Berkrot)