United States Geological Survey scientists have shared maps that show where ash would fall across the US if a Yellowstone ...

Tephra is a general term for fragments of volcanic rock and lava that are blasted into the air by explosions or carried upward by hot gases. Tephra includes large, dense chunks, light rock debris ...

Gas emissions and rock fragments ejected from the volcano into the air, known as tephra, were the primary hazards from the eruption, the observatory said. A few hours later, another observatory ...