Introduction;
An earthquake is a wave that travels through the earth, often causing an earthquake or an explosion. In general, after an earthquake occurs inside the earth and the energy of the earth is released, the released energy is released in the form of vibrational waves in all directions and transmits the earthquake with them. Earthquake waves are studied by seismologists and measured by seismographs and seismometers.

Investigating the types of earthquake waves

Earthquake waves are divided into two categories according to their motion inside or on the earth's surface:

Internal or physical waves:
They are a series of seismic waves that travel through the earth and propagate in all directions, moving faster than surface waves. Internal waves can also be divided into longitudinal or primary waves and transverse or secondary waves.

Surface waves:
Surface waves are slower than transverse waves, and their intensity decreases rapidly with respect to depth and distance from the center. These waves are created under special conditions and in the common season of both gas and liquid environments due to earthquakes caused by earthquakes. It has the most energy from shallow shocks and is the main cause of earthquake damage, especially in residential areas. These waves begin to vibrate after interfering with internal waves along the boundary and have a limited penetration depth, so they are always concentrated near the levels of discontinuity. Therefore, we will not have surface waves in homogeneous environments. These waves, also known as finite wave or guided waves, are divided into four primary categories (P), secondary (S), lava (LOVE), and Riley (LR), and are characterized by characteristics such as velocity, amplitude, and amplitude. , Wavelength, periodicity, and frequency are distinguished from each other. Secondary waves, Lau and Riley are very complex and have much more destructive power than the primary wave.

At a distance of about 120 km from the epicenter, the first wave to reach the seismograph station from the epicenter (18 km deep) is the initial wave. The speed of this wave is 6 to 6.5 km. Then comes the secondary wave and then the lava and Riley waves. The speed of the primary waves is about 1.73 times that of the secondary waves.

Different characteristics of earthquake waves

Primary longitudinal waves (P)
They are the first waves to make slight shocks to the ground at the time of the earthquake, they are hard to feel and are not destructive. These waves cause successive stretches and contractions along the wave motion. The propagation speed of these waves is higher than other waves and they are the first waves to reach the seismograph station.
Condensation waves pass through all environments that can withstand pressure, including gases, solids, and liquids. Particles affected by the initial wave (P) oscillate forward or backward to propagate the wave.
For example, consider a part of a spring that is collapsed and released suddenly, the compression will travel the entire length of the spring to the end. The spring example vibrates in the direction of the wave motion, which is very similar to how the primary waves propagate (P). The reason for naming these waves as primary waves is the high speed of these waves. Because the first wave to be felt from an earthquake is the initial waves (P). Despite the high speed of transmission, these waves, because they die much faster than other waves (ie, lose their energy), do not cause much damage in an earthquake.

Secondary shear waves (S)
These waves start 5 to 6 seconds after the initial waves (P) and are more intense and destructive, only passing through solids, causing the rock to bend and lose its shape, and fall a few seconds later. The rubble begins. Almost all earthquakes are caused by shear waves, which means that when the rock breaks, the rock breaks and the adjacent points of the gap move sideways. It is at this time that two types of primary (P) and secondary (S) waves are created.
These waves propagate only in environments that can withstand lateral deformation, such as solid environments, and cannot be transported in liquids and gases.
For example, if we attach one rope to a wall and hold the other end in our hand and move it upright, a wave is created in the rope, similar to secondary waves (S). The wave travels along the length of the rope while the rope particles vibrate in a direction perpendicular to the length of the rope. These waves vibrate the particles of the perpendicular to the direction of the wave.

Love waves
The motion of the earth by the lava wave is almost similar to that of the secondary wave (S), with the difference that the particles of matter move parallel to the earth's surface in a direction perpendicular to the propagation of the wave, and the particles do not move on a vertical plane. The propagation of these waves moves side by side in a layer-by-layer ground, and the propagation of these waves is like the vibrations caused by the movement of the rope to the left or right. Love waves move a little faster than Riley waves (LR) and appear faster on seismicity.
Riley Waves (LR)
These waves move in a special way and are similar to the waves of the oceans that move in a vertical plane and in the direction of the propagation of the waves, so that the motion of the particles takes place along the circular or elliptical circuits. However, the direction of rotation of the circles is opposite to the movement of the ocean waves, and the motion of the rock particles undergoes a reversible elliptical orbit on the vertical plane toward the source of the earthquake, causing severe earthquakes on the surface of the earth but rapidly receding.

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The accuracy of Imen Khab Hooshmand anti-earthquake smart beds in detecting earthquake waves is very high and it is proud to announce that this exclusive product is equipped with a completely intelligent and vibration-sensitive system with at least 2.5 Richter and in case of mild occurrence, the most vibration. The fully intelligent anti-earthquake bed sensor senses the initial waves (P) before humans and automatically starts to close its protective and resistant fins within 3 seconds, which starts to destroy the safety space for the person or persons by starting the destructive waves. Lying in bed provides shelter from falling debris and falling objects.
It should be noted that if the accident does not cause any damage and does not happen, 3 minutes after the accident and the end of the accident, the protective fins will open automatically and will be in the original state.

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