In earthquakes, longitudinal waves propagate quickly.
Longitudinal waves are propulsive waves with a propagation speed of 5.5 to 7 kilometers/second in the earth's crust. They are the first to arrive at the epicenter. They are also called P waves. They cause the ground to vibrate up and down and are less destructive.
Transverse waves are shear waves: they propagate in the earth’s crust at a speed of 3.2 to 4.0 kilometers/second, and are the second to reach the epicenter. They are also called S waves. They cause the ground to shake back and forth, left and right, and are destructive. Stronger.
Earthquakes are divided into three types according to their propagation modes: longitudinal waves, transverse waves and surface waves. Longitudinal waves are propulsive waves, with a propagation speed of 5.5 to 7 kilometers/second in the earth's crust, and are the first to arrive at the epicenter. Also known as P wave, it causes the ground to vibrate up and down and is weakly destructive. Transverse waves are shear waves: their propagation speed in the earth's crust is 3.2 to 4.0 kilometers/second, and the second one to reach the epicenter is also called S wave. It causes the ground to shake front and back, left and right, and is highly destructive. Surface waves, also called L waves, are mixed waves excited by longitudinal waves and transverse waves when they meet on the surface. Its wavelength is long and its amplitude is strong, and it can only propagate along the ground surface. The main factors causing severe damage to buildings