In the summer of 1831, people across the Northern Hemisphere witnessed a surreal transformation in the sky. The Sun appeared ...

Roundtop is located on Unimak Island, is glacier-covered today but much of the southwestern parts of the Alaska Peninsula are covered with volcanic debris and ash (aka, tephra) from its VEI 5 ...

Tephra includes large, dense chunks, light rock debris, and ash. The restless lava lake in Nyiragongo's summit crater regularly causes eruptions of gas and smoke laden with tephra. Lava is the ...

Eruptions of steam, ash, and tephra continued until June 1917, when the volcano resumed its quiet profile, with minor steam clouds occasionally reported. Since 1921, Lassen Peak has remained quiet.

Timelapse satellite imagery captured Hawaii’s Kilauea volcano erupting during its latest episode on Tuesday, April 22.The Cooperative Institute for Research in the Atmosphere (CIRA) released the ...

Hazards during Tuesday's eruption included volcanic gas emissions, as well as windblown volcanic glass, known as Pele's hair, and tephra. Tephra is rock fragments and other debris ejected from a ...