Pressure building inside the Pu‘u ‘Ō‘ō crater on Kīlauea Volcano at Hawai'i Volcanoes National Park could lead to a new vent at any time, according to the Hawaiian Volcano Observatory.

Tuesday afternoon the observatory said building pressure and measurements over the past month suggest that the magma system beneath Pu‘u ‘Ō‘ō "has become increasingly pressurized. If this activity continues, a new vent could form at any time, either on the Pu‘u ‘Ō‘ō cone or along adjacent areas of the East Rift Zone."

As of April 13, geologists had observed scattered breakouts about 1.5 miles from Pu‘u ‘Ō‘ō, "and a sluggish breakout" a little more than 3 miles from the crater. "During the past few weeks, lava flows have also erupted onto the Pu‘u ‘Ō‘ō crater floor," they added.

"Since mid-March, a tiltmeter and GPS station on Pu‘u ‘Ō‘ō have recorded a pronounced inflationary trend of the cone, and recent webcam images have detected simultaneous uplift of the Pu‘u ‘Ō‘ō crater floor by several meters (yards)," the observatory said in an alert. "These observations provide evidence that magma is accumulating at shallow depths beneath Pu‘u ‘Ō‘ō.

"Similar episodes of inflation and uplift of the crater floor at Pu‘u ‘Ō‘ō occurred in May–June 2014 and May 2016. These episodes preceded the opening of new vents on Pu‘u ‘Ō‘ō that produced the June 27th flow (active 2014-2016) and the (Episode) 61g flow (active since 2016), respectively."

The observatory noted that due to volcanic hazards, the Hawaii Department of Land and Natural Resources has restricted public access to the Kahauale‘a Natural Area Reserve since 2007.

According to the geologists, "a new vent located on the cone of Pu‘u ‘Ō‘ō would erupt lava flows onto one or more sides of the cone that would initially advance downslope rapidly within a few kilometers (miles) from the vent. Because of the potential for a sudden breakout anywhere on Pu‘u ‘Ō‘ō, the cone is extremely hazardous. The location of a new vent or potential lava-flow paths cannot be estimated until such time that a new vent forms and stabilizes."

Kīlauea Volcano’s East Rift Zone "eruption began in January 1983 with high lava fountains that built a cinder-and-spatter cone, later named Pu‘u ‘Ō‘ō. Subsequent activity included continuous lava effusion from vents on Pu‘u ‘Ō‘ō or within a few kilometers (miles) east or west of Pu‘u ‘Ō‘ō. Most of the lava flows erupted from these vents have advanced down the south flank of Kīlauea, often reaching the ocean," the observatory noted.