a group of persons, as employees, charged with carrying out the work of an establishment or executing some undertaking. a group of assistants to a manager, superintendent, or executive. a member of a staff.
Seismic waves are the waves of energy caused by the sudden breaking of rock within the earth or an explosion. They are the energy that travels through the earth and is recorded on seismographs. Types of Seismic Waves. There are several different kinds of seismic waves, and they all move in different ways.
An earthquake releases energy as shock waves, the so-called seismic waves, which ripple across the earth's surface. The seismic waves created as they move from the epicentre an earthquake vary. What is amazing is how fast they can travel: up to 2 miles per second in granite! Seismic waves can be classified into two basic types: body waves which travel through the Earth and surface waves, which travel along the Earth's surface.