How many types of Seismic waves - Geography for You

Seismic waves

The waves that originate from the earthquake are called earthquake waves. In 1755, the Seismologist 'John Michel' discovered the earthquake waves. According to the nature of the wave, earthquake waves can be divided into two main and four subdivisions.

1. Body wave - A body wave is a seismic wave that moves through the interior of the earth, as opposed to surface waves that travel near the earth's surface. It can be divided into two parts.

A. Primary wave or P wave - This wave is first detected in the seismograph and is detected as a primary wave.

➽ Characteristics- 1 As the wave moves towards it, the rock is tremble in parallel to it, it is known as a longitudinal wave. 2. As it flows through contraction and expansion of substances, it is called contraction wave. 3. Along with this wave flow, the particles of the material move forward and backward, so this is called a 'push-pull wave'. 4. Its wavelength is less. 5. Maximum speed is about 5-14 km/sec 6. As it shocks, it is called a push wave. 7. This wave can flow through solid, liquid and gaseous conditions of the substance. 8. It is the most powerful but the least power to destroy.

Fig. Primary or P waves (on top) and secondary or S waves (on bottom) in motion

Image courtesy of Actualist, Wikipedia Books

B. Secondary wave or S wave - A transverse earthquake wave that travels through the interior of the earth and is usually the second conspicuous wave to reach a seismograph.

Courtesy

➽ Characteristics- 1. Wherever this wave is switched, the mass particles of the medium vibrate in its right angles or vertices, so it’s called transverse wave. 2. The wave causes strong substances to be triggered, so it is called a tremor wave. 3. It is medium velocity. 3.5 to 7.2 km / second. 4. Its wave length is larger than the P wave and smaller than the L-wave. 5. It only flows through Solid objects. 6. It is medium-sized and medium of destruction.

2. Surface wave or L wave - A seismic wave that travels across the surface of the Earth as opposed to through it.

Types of Seismic wave (Courtesy)

➽ Characteristics- 1. This wave is created from the epicenter. 3. The most slower and lasting waves. 4. Only flow through the solid material of the crust. 5. Its wave length is the largest, so its long waves say. 6. Its speed is less than the other waves. About 3.5 to 5 km per second. 7. It can be divided into two parts - (A) Rally waves - flows vertically in the direction of the surface. That is, it has characteristics of P waves. In 1855, the inventor of the British physicist Lord Rally. (B) Love wave - flows horizontally along the surface of the earth. Which carries the characteristics of the S wave. It is called the LQ (Lateral Querwellen) wave. In 1911 a British mathematician. E. H. Love inventor of Love wave.  8. The power of this wave is the lowest but the most destructive power.

Table of various minerals and their P and S wave velocities and density

Courtesy of Stanford Rock Physics Laboratory

➤ Know anything else

➥Who Discover the P, S, L waves- R. D.Oldham

➥Who Discover the Pg-Sg wave- Jeffreys

➥Who Identify P*-S* set of Seismic waves- Conard

➥Who introduce the term “Seismology”- Robert Mallet”.

➥Which Seismic wave is minimum velocity- Pg-Sg Waves

➥Which Seismic wave is maximum velocity- P-S waves.

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