Question

 1. Define the following terms: earthquake, seismic wave, seismograph, seismogram.

 2. What are the basic types of seismic waves? Which seismic wave travels along the surface of Earth? Which seismic wave travels through Earth's interior?

 3. Which seismic wave travels fastest? Which seismic wave travels slowest?

 4. What is the difference between an earthquake epicenter and an earthquake focus?

 5. How many different earthquake recordings are needed to locate an earthquake epicenter?

Answer 1

Answer 1 - Earthquake is the sudden vibration on the earth’s surface may be due to natural or anthropogenic/manmade factors.

Seismic waves are the vibrations or waves released during earthquake.

Seismograph is the instrument used to measure earthquake automatically.

Seismogram is the graphical output of seismograph.

Answer 2 - There are two basic types of seismic waves i.e. Body waves and Surface waves.

Surface wave moves on the earth’s surface where as Body waves moves under the surface.

Answer 3 - Primary or P wave travels fastest. It is a Body wave.

Surface waves are the slowest waves.

Answer 4 - Earthquake Focus or also known as the Hypocenter is the origin place of earthquake located under the surface.

Earthquake Epicentre is the place on the earth’s surface which is perpendicular to Focus where maximum damage occurs.

Answer 5 - Minimum 3 different earthquake recordings are needed to locate an earthquake epicenter.