![]() Įarthquake swarms are sequences of earthquakes striking in a specific area within a short period of time. ![]() Aftershocks are formed as the crust adjusts to the effects of the main shock. An aftershock is in the same place of the main shock but always of a smaller magnitude. Ī foreshock is an earthquake that happens before a larger earthquake, called the mainshock.Īn aftershock is an earthquake that happens after a previous earthquake, the mainshock. Most earthquake clusters consist of small tremors which cause little to no damage, but there is a theory that earthquakes can recur in a regular pattern. Most earthquakes form part of a sequence, related to each other in terms of location and time. Strike-slip faults are steep structures where the two sides of the fault slip horizontally past each other.Įarthquake clusters Reverse faults occur in areas where the crust is being shortened. Normal faults occur mainly in areas where the crust is being extended. There are three main types of geological fault that may cause an earthquake: normal, reverse (thrust) and strike-slip. In Luoyang in 133 AD, it detected an earthquake 400 to 500 km (250 to 310 mi) away Model of ancient seismometer with pendulum sensitive to ground tremors. These are called collapse earthquakes.Įarthquake fault types Collapse Earthquakes: In areas of intense mining activity, often the roofs of underground mines collapse and minor tremors take place. However, these are confined to areas of active volcanoes.Ģ. Volcanic Earthquakes: Earthquakes which are caused by volcanic eruptions are quite devastating. The San Andreas fault in San Francisco, and Rift valley fault in Africa are faults like this.ġ. This releases the stored energy as shock waves. This continues until the stress rises and breaks, suddenly allowing sliding over the locked portion of the fault. When they stick, motion between the plates leads to increasing stress. The boundaries between moving plates form the largest fault surfaces on Earth. The main cause is when tectonic plates ride one over the other, causing orogeny (mountain building), and severe earthquakes. Tsunamis can also create a lot of destruction.Įarthquakes are caused by tectonic movements in the Earth's crust. An earthquake under the ocean can create a huge wave called a tsunami. But we do know where earthquakes have a high chance of happening in the future, like close to fault lines. No one can tell when an earthquake will happen. The largest earthquake ever measured was a 9.5. And magnitude 5 (or more) damages over a wide area. On this scale, 2 is shaking that can not be noticed easily. The Richter Scale was invented by Charles Francis Richter in 1935. The strength, or magnitude, of an earthquake can be measured using the Richter scale. A seismometer detects Earth's shaking and draws the shaking on a seismograph. The effect of an earthquake can be measured by a seismometer. The strength, or magnitude, of an earthquake, can be measured using the Richter scale. A seismometer detects the shaking and puts these movements on a seismograph. Seismology studies the cause, repeats, type, and size of earthquakes. The sudden release of tension in the tectonic plates sends waves of energy that travel through the Earth. There can be many earthquakes over a short period of time in a small area. People who study about earthquakes are called seismologists. The epicenter is the point at ground level directly above the hypocenter. An earthquake's first point of rupture is called its hypocenter, or focus. The earthquake happens when the tectonic plates are suddenly released, so they start to move very quickly. When they get stuck, they build up tension. The different tectonic plates slowly move past each other. Strong or high-magnitude earthquakes damage buildings.ĭisturbances in the balance of the earth cause earthquakes. ![]() San Francisco, California earthquake, sometime in 1906Īn earthquake is when Earth's tectonic plates shake and move Earth's surface.
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