Science earthquakes

Effects of earthquake

The length of the wiggle depends on the size of the fault, and the size of the wiggle depends on the amount of slip. Shallow earthquakes cause the most damage because the focus is near the Earth's surface where people live. The energy from an earthquake travels through Earth in vibrations called seismic waves. A tsunami overwhelms the ships in the harbor. S-waves are slower and so are the second waves to reach a seismometer. The largest, main earthquake is called the mainshock. Using what you know about plate tectonics and elastic rebound theory, describe what is taking place in the Cascades Mountains of the Pacific Northwest, including northern California. As is typical for tsunami, the waves were not noticeable in open water. There are many other faults spreading off the San Andreas Fault, which together with the main fault produce around 10, earthquakes a year Figure 7. What did Tilly Smith notice on the beach in Thailand that caused the adults around her to evacuate the beach before the enormous tsunami hit in ? Appel's widely anthologized short story, A Comparative Seismology, features a con artist who convinces an elderly woman that an apocalyptic earthquake is imminent. The energy radiates outward from the fault in all directions in the form of seismic waves like ripples on a pond. Therefore, the longer the length and the wider the width of the faulted area, the larger the resulting magnitude. A seismometer detects seismic waves below the instrument and records them as a series of zig-zags. The further you are from the storm, the longer it will take between the lightning and the thunder.

These are smaller earthquakes that happen in the same place as the larger earthquake that follows. What did Tilly Smith notice on the beach in Thailand that caused the adults around her to evacuate the beach before the enormous tsunami hit in ?

The size of the earthquake is called its magnitude. In lab experiments where scientists would simulate earthquakes with sensitive equipment, there would always be small earthquakes that came before the main quake.

Earthquake causes

The energy released was approximately twice that of the next most powerful earthquake, the Good Friday earthquake March 27, which was centered in Prince William Sound , Alaska. Like other waves, a tsunami wave has a crest and a trough. Surface waves do the most damage after an earthquake. Activities Take a ten question quiz about this page. For the new study, Trugman and Ross decided to focus on 46 of the largest quakes in Southern California between and while excluding those that were aftershocks of other larger events. Shaking and ground rupture are the main effects created by earthquakes, principally resulting in more or less severe damage to buildings and other rigid structures. Many earthquakes are caused by movement on faults that have components of both dip-slip and strike-slip; this is known as oblique slip. Depending on the size of the mainshock, aftershocks can continue for weeks, months, and even years after the mainshock!

Once the fault has locked, continued relative motion between the plates leads to increasing stress and therefore, stored strain energy in the volume around the fault surface.

An aftershock is in the same region of the main shock but always of a smaller magnitude.

earthquake essay

An earthquake is what happens when two blocks of the earth suddenly slip past one another. The earthquakes can be shallow, intermediate or deep focus. The larger the number on the MMS scale, the larger the earthquake.

Earthquakes facts

Yet the Cascadia subduction zone is one of the world's quietest subduction zones, with relatively few earthquakes. Shallow earthquakes cause the most damage because the focus is near the Earth's surface where people live. The largest in the US was a 9. Earth's crust is fractured into tectonic plates that have been moving very slowly over the Earth's surface for millions of years. If weather does affect earthquake occurrence, or if some animals or people can tell when an earthquake is coming, we do not yet understand how it works. Of all these the release of elastic strain is the most important cause, because this form of energy is the only kind that can be stored in sufficient quantity in the Earth to produce major disturbances. There are two types of surface waves. This continues until the stress has risen sufficiently to break through the asperity, suddenly allowing sliding over the locked portion of the fault, releasing the stored energy. Other times, it would appear as a widespread increase in the earthquake rate in the general area before the mainshock. On average, the kilometer distance to the earthquake is the number of seconds between the P and S wave times 8.
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Science for Kids: Earthquakes