![]() ![]() Depending on the size of the mainshock, aftershocks can continue for weeks, months, and even years after the mainshock! What causes earthquakes and where do they happen?Ī simplified cartoon of the crust (brown), mantle (orange), and core (liquid in light gray, solid in dark gray) of the earth. These are smaller earthquakes that occur afterwards in the same place as the mainshock. Mainshocks always have aftershocks that follow. ![]() The largest, main earthquake is called the mainshock. Scientists can’t tell that an earthquake is a foreshock until the larger earthquake happens. These are smaller earthquakes that happen in the same place as the larger earthquake that follows. The location below the earth’s surface where the earthquake starts is called the hypocenter, and the location directly above it on the surface of the earth is called the epicenter. The surface where they slip is called the fault or fault plane. Swells characteristically exhibit smoother, more regular, and uniform crests and a longer wave length than wind waves.A normal (dip-slip) fault is an inclined fracture where the rock mass above an inclined fault moves down (Public domain.)Īn earthquake is what happens when two blocks of the earth suddenly slip past one another. Swell: Wind-generated waves that have travelled out of their generating area. ![]() Breaking waves have a deep trough surging waves do not.Ĭhop: Many small waves causing the ocean surface to be rough. As a result, the wave is slow, the faces are smooth and oblique, and the crest barely exists. Surging waves are the result of long period swells.A collapsing wave is a mix of spilling and plunging waves.They can be powerful barrels or enormous close-outs. Plunging waves break when the ocean floor is steep or has sudden depth changes.These waves break when the ocean floor has a gradual slope. Spilling waves are gentle waves with crests that break softly towards the shore.There are four basic types of breaking waves: spilling, plunging, collapsing, and surging. Friction with the bottom causes the trough of the wave to disappear, the crest to slow its movement, and when the depth causes the wave height to become 1.3 times the water depth, the crest falls, forming a breaker. As a wave approaches the coast, it becomes shorter in length and more abrupt, increasing its height. Waves travel with little change across the vast expanses of the open ocean, but eventually all waves must reach shore. Ripples are often called capillary waves. This creates stress on the water and results in tiny short wavelength waves called ripples. Ripples: The ruffling of the water’s surface due to pressure variations of the wind on the water. The greater the fetch, the greater the wave height. one wave every 6 seconds.įetch: The uninterrupted area or distance over which the wind blows (in the same direction). The wave period is often referenced in seconds, e.g. Wave Period: The time it takes for two successive crests (one wavelength) to pass a specified point. Wave Frequency: The number of waves passing a fixed point in a specified period of time. Wave Length: The distance between two consecutive wave crests or between two consecutive wave troughs. Wave Height: The vertical distance between the wave trough and the wave crest. water) from one location to another location. Wave: The repeating and periodic disturbance that travels through a medium (e.g. water) from one location to another location. SECOORA created a handy online glossary helps students learn the most common scientific words heard in reference to waves. Waves are repeating and periodic disturbance that travels through a medium (e.g. ![]()
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