Volcanoes produce a wide variety of natural hazards that can kill people and destroy property. This simplified sketch shows a volcano typical of those found in the Western United States and Alaska, but many of these hazards also pose risks at other volcanoes, such as those in Hawaii. Some hazards, such as lahars and landslides, can occur even when a volcano is not erupting.
A sphincter is a ring of muscle which holds any kind of biological opening closed. Sphincters are an important part of almost any system in a body. They help to both regulate the exit, entrance and circulation of fluids, gasses, and solids.
Making the world better, one answer at a time. The Upper Esophageal Sphincter is a ring of skeletal muscle that controls the movement of food from pharynx to esophagus.he ring of muscle between the esophagus and stomach is called the  sphincter. The sphincter allows the food to enter the stomach, but  stops the acidic contents from enteri â¦ ng the esophagus.