Tephra refers to the solid material ejected during a volcanic eruption. This material can include a variety of particles, such as ash, pumice, and volcanic rock fragments. Tephra is classified based on its size, with ash being the smallest particles, typically less than 2 millimeters in diameter, while larger fragments are categorized as lapilli or volcanic bombs. When tephra falls to the ground, it can cover large areas, impacting the environment and human activities. The accumulation of tephra can affect air quality, damage crops, and disrupt transportation. Understanding tephra is essential for assessing volcanic hazards and mitigating risks associated with eruptions from volcanoes like Mount St. Helens or Kilauea.