Although louisiana lies in an area of low seismic risk, a number of historical earthquakes have occurred in our state. But this skin is not all in one piece it is made up of many pieces like a puzzle covering the surface of the earth. Students write their own myth in the starter and then write to the tribe in the plenary to explain why earthquakes actually happen. Learn about the geophysics behind earthquakes, how they are measured, and where the most powerful earthquake ever witnessed occurred. Earthquakes can range in size from those that are so weak that they cannot be felt to those violent enough to propel objects and people into the. Damage is greatest from shallow earthquakes because the. Check yourself for injuries and get first aid, if necessary, before helping injured or trapped persons. When two blocks of rock or two plates are rubbing against each other, they stick a little. Therefore, earthquakes are most frequent along the edges of the tectonic plates where one plate is moving relative to the adjoining plate. Earthquakes develop when tectonic plates, the massive jigsaw pieces that make up the crust of the earth, move suddenly, sending shockwaves through neighboring area. Earthquakes are measured using instruments called seismometers that detect the vibrations caused by seismic waves as they travel through the crust.
When the stress on the edge overcomes the friction, there is an earthquake that releases energy in waves that travel through the earths crust and cause the shaking that we feel in california there are two plates the pacific plate and the. The movement of earths crust resulting from the release of built up potential energy between two stuck tectonic plates. Earthquakes can leave behind incredible devastation, while also creating some of the planets most magnificent formations. Earthquakes occur all the time all over the world, both along plate edges and along faults. An earthquake also known as a quake, tremor or temblor is the shaking of the surface of the earth resulting from a sudden release of energy in the earth s lithosphere that creates seismic waves. Most earthquakes occur along the edge of the oceanic and continental plates. This sudden release of energy causes the seismic waves that make the ground shake. They have tended to be of low magnitude and occur with low frequency. Most of the deaths are when people are trapped in falling buildings. The shaking is caused by movements in earths outermost layer. When large earthquakes occur in such areas the results can be catastrophic, with terrible loss of human lives and untold economic cost.
How earthquakes happen if you would like a printable, nonanimated version of this graphic, click on the following link to open a pdf file and then follow the icon to print that file. These plates fit together like puzzle pieces but they. How does earthquake occur with explanation social science. Based on the depth of their foci, earthquakes are classified into tree types. Faults or slipping zones the surfaces where these plates slip are termed as fault planes or faults, and the plate boundaries are made up of several such faults or slipping zones. The earths crust the outer layer of the planet is made up of several pieces, called plates. Expect and prepare for potential aftershocks, landslides or even a tsunami if you live on a coast. Earthquakes are usually caused when rock underground suddenly breaks along a fault. Most computers will open pdf documents automatically, but you may need to download adobe acrobat reader.
An earthquake is caused by a sudden slip on a fault. Chapter 12 earthquakes section 1 how and where earthquakes happen. Earthquakes happen when these plates move under, slide past one another, or collide into one another. Printable pdf of earthquakes booklet bgs earthquake british. Scientists cant tell that an earthquake is a foreshock until the larger. The usgs earthquake hazards program is part of the national earthquake hazards reduction program nehrp, established by congress in 1977, and the usgs advanced national seismic system anss was established by congress as a nehrp facility. In the offshore region to the west of vancouver island, more than 100 earthquakes of magnitude 5 or greater large enough to cause damage had they been closer to land have occurred during the past 70 years. Today, earthquakes are often predicted as is the potential destruction they may cause.
Learn vocabulary, terms, and more with flashcards, games, and other study tools. Earthquake safety earthquake preparedness red cross. The nature and cause of earthquakes kitp online talks. An earthquake is what happens when two blocks of the earth suddenly slip past one another. Tectonic plates are what make up the earths crust, its outermost layer. Sep 05, 2012 based on the depth of their foci, earthquakes are classified into tree types. Can cause major damage to poorly constructed buildings over small regions. What is an earthquake and what causes them to happen. Task 2 using the worksheet below, explain with the aid of a diagram how earthquakes happen.
Earthquakes happen deep underground along tectonic plate boundaries. The stress can cause the rock to slip and cause earthquakes. Geological survey general information product presents some of the new understanding gained and sci. These plates slowly move over a long period of time.
Most earthquakes happen near the boundaries between plates. Rotating powerpoint with different myths and legends that explain why earthquakes happen. Each time you feel an aftershock, drop, cover and hold on. During a geology lesson consider taking a day or two to study the science of earthquakes. They have had about 12,000 earthquakes in the last 30.
Surveyors went to mountain peaks to relocate the property. Over 90% of earthquakes including almost all of the largest and most destructive ones happen at or near socalled plate boundaries, where the 15 or so major subdivisions plates of the earths crust and uppermost mantle move towards, alongside, or away from each other 1. These are smaller earthquakes that happen in the same place as the larger earthquake that follows. The earth is made of an inner core, an outer core and a mantle, and the final layer is a thin crust covering the mantle, which. An aerial view of the san andreas fault in the carrizo plain, central california. Mar 24, 2020 earthquake, any sudden shaking of the ground caused by the passage of seismic waves through earths rocks. The crust and the top of the mantle make up a thin skin on the surface of our planet. Earthquakes are the result of plate tectonics, or shifting plates in the crust of earth, and quakes occur when the frictional stress of gliding plate boundaries builds and causes failure at a. This causes shock waves to shake the surface of the earth in the form of an earthquake. Earthquake science explained is a series of short articles for students, teachers, and parents originally published as weekly features in the san francisco chronicle. Alaska has more earthquakes than any other us state. The surface where they slip is called the fault or fault plane. No detected earthquakes have definitely been attributed to any of the specific mapped fault systems.
May 12, 2020 an earthquake is an intense shaking of earths surface. An earthquake is the vibration, sometimes violent, of the earths surface that follows a release of energy in the earths crust. The pacific coast is the most earthquakeprone region of canada. Earthquakes teacher notes and student activities ga record. Earthquakes usually occur on the edges of large sections of the earths crust called tectonic plates. Additionally, if an earthquake occurs in a distant place especially if the hypocenter is shallow large and slow swaying can occur after the ground. Earthquakes are one of the most costly natural hazards faced by the nation, posing a significant risk to 75 million americans in 39 states. Seismic waves can be both natural from earthquakes or caused by human activity explosions. The movements of the plates put stress on the rock in the plates. Earthquake science explained is a series of short articles for students, teachers, and parents. Depending on the size of the mainshock, aftershocks can continue for weeks, months, and even years after the mainshock.
The risks that earthquakes pose to society, including death, injury, and economic loss, can be greatly reduced by 1 better planning, construction, and mitigation practices before earthquakes happen, and. The tectonic plates are always slowly moving, but they get stuck at their edges due to friction. You should aim to use the following words in your description. Although the earth looks like a pretty solid place from the surface, its actually extremely active just below the surface. Learn more about the causes and effects of earthquakes in this article. Earthquakes occur most often along geologic faults, narrow zones where rock masses move in relation to one another. Earthquake magnitude earthquake severity richter magnitude earthquake effects less than 3. Various societies have produced earthquake legends to explain these natural.
Earthquakes happen when two large pieces of the earths crust suddenly slip. Earthquakes teacher notes and student activities 7 the causes and types of earthquakes most earthquakes are caused by the movement of the earths tectonic plates. Jun 01, 2009 how earthquakes happen if you would like a printable, nonanimated version of this graphic, click on the following link to open a pdf file and then follow the icon to print that file. Discuss why they happen and how scientists measure and predict them. Fences across the san andreas fault ripped apart, and it was no longer clear who owned the land nearby. How and where earthquakes happen continued where do earthquakes happen. An earthquake occurs when earths surface shakes because of the release of.