As many people use the term sea and the ocean interchangeable when speaking but the sea is generally smaller than the oceans and is usually surrounded by the land areas or maybe partly enclosed firm example as the Bering Sea in the pacific ocean.
Mudflows of volcanic eruptions are the most dangerous, and are called lahars. A lahar is a type of mudflow or debris flow composed of a slurry of pyroclastic material, rocky debris, and water.
