What is a hot, high-velocity mixture of ash, gas, and pumice that flows like a liquid down slopes called?

The term that accurately describes a hot, high-velocity mixture of ash, gas, and pumice flowing down slopes is pyroclastic flow. This phenomenon occurs during explosive volcanic eruptions when volcanic material is expelled at high speeds. Pyroclastic flows can reach temperatures of about 1,000 degrees Celsius and can travel at speeds exceeding 700 km/h, making them extremely dangerous.

Understanding the characteristics of pyroclastic flows is crucial in volcanic studies, as they are among the most destructive volcanic events due to their speed and the high energy they carry. This mixture is different from other volcanic flows, such as lava flows, which consist mainly of molten rock and do not typically contain gas and ash in the way pyroclastic flows do.

By recognizing pyroclastic flows, one can differentiate between the various volcanic phenomena and their effects on surrounding landscapes and human settlements.