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.
Seismic waves travel through the earth during an earthquake. They occur when stress at a plate or other regions on the earth is released. Waves that travel through the crust are called surface waves. These cause most of the damage associated with earthquakes. Waves that travel through deeper layers are called body waves.