Why do seismic waves curve

An increase in one integer means that thirty times more energy was released. These two scales often give very similar measurements. How does the amplitude of the largest seismic wave of a magnitude 5 earthquake compare with the largest wave of a magnitude 4 earthquake? How does it compare with a magnitude 3 quake?

The amplitude of the largest seismic wave of a magnitude 5 quake is 10 times that of a magnitude 4 quake and times that of a magnitude 3 quake. Each scale has their benefits. As mentioned above, the Mercalli Intensity scale is based on how much damage someone would see. This is relative though because some places have strong building codes, and the rock material underneath will impact ground shaking without changing the energy released at the focus.

With the Richter scale, a single sharp jolt measures higher than a very long intense earthquake that releases more energy. The moment magnitude scale more accurately reflects the energy released and the damage caused. Today, most seismologists now use the moment magnitude scale. Skip to main content. Tectonic Forces. Search for:. A surface wave travels along the surface of the Earth. It is the slowest of the three types of seismic wave.

Surface waves usually have larger amplitude than the other waves and cause the most damage. A P wave is a longitudinal wave and travels the fastest.

Refraction of seismic waves causes them to curve away from a direct path. Reflection causes them to glance off certain surfaces e. The result of this behavior, in combination with the fact that S-waves can not travel through liquids, is the appearance of seismic shadows, opposite of the actual earthquake site. This suggests that the peridotite within this zone contain a few percent partial melt, but not enough to completely stop the S-waves. This region is therefore referred to as the low velocity zone or asthenosphere.

From km depth, the velocity of S-waves gradually increases again until reaching the km transition zone where the S-wave velocity increases rapidly. This increase may the associated with a change in the crystal structure of olivine to a closer atomic packing referred to as the spinel structure.

P-waves speed up again through the inner core and S-waves also travel through it, suggesting that the inner core is composed of solid iron and nickel.