Seismic Wave Facts

Seismic waves are vibrating movements of the ground caused by underground explosions, volcanic eruptions, and man-made explosions that can vibrate the ground.

When magma escapes through cracks in the Earth’s crust, seismic waves occur. Small earthquakes may rattle the windows of buildings, but large earthquakes may bring them to rubble.

Seismic waves can help us understand how the Earth works. It is used for predicting future earthquakes. Seismic waves travel at speeds from hundreds to thousands of miles per hour.

The speed depends on the size of the earthquake.

Seismic Wave Facts for Kids

• Energy waves that travel on and through the Earth
• Caused by earthquakes, explosions, or a volcano
• Geophysicists calculate seismic waves
• S waves and P waves are common types of seismic waves
• Seismometers don’t always detect seismic waves
• Seismographs are set up all over the world to monitor Earth’s movement
• They are recorded by a seismometer, an accelerometer, and a hydrophone for underwater earthquakes

Types of Waves

There are many types of seismic waves, but body waves travel through the Earth, and surface waves travel at the Earth’s surface.

Surface waves travel across the surface more slowly than body waves and cause more damage.

Body Waves

Primary waves move through solids and liquids faster than any other waves, and they squeeze and stretch the ground back and forth.

We call secondary waves secondary because they arrive after primary waves. Secondary waves change the shape of materials.

S-waves are shear waves that travel perpendicular to the direction of propagation and displace the ground perpendicular to the propagational direction. S-waves can’t travel through fluids, so the absence of S-waves in the outer core suggests a liquid state.

Surface Waves

Seismic surface waves travel on the Earth’s surface and travel more slowly than seismic body waves.

Rayleigh waves

Rayleigh waves travel in an oval shape similar to water waves. They are slower than Love waves. The existence of Rayleigh waves was predicted in 1885, but the existence of these waves depends on the frequency and wavelength of the waves.

Love waves

Love waves were named after A.E.H. Love. Love waves travel faster than Rayleigh waves. Love waves are horizontally polarized shear waves that travel at about 90% of Rayleigh waves velocity. They have the largest amplitude.

Stoneley wave

A Stoneley wave is a boundary wave that propagates along the boundary between two contacting media. They can be generated along the walls of a fluid-filled borehole and are an important source of coherent noise in vertical seismic profiles and sonic logging.

Can Tectonic Plates Cause Seismic Waves

Earth’s tectonic plates movement can be detected, but explosions, volcanoes, and landslides can also cause seismic waves.

Detection

A seismometer is a scientific instrument that responds to ground noises and shaking. It is used to record earthquakes and is used to study the Earth’s internal structure.

The first seismometer was invented in China during the 2nd century. In 1856 an electromagnetic seismometer was developed.