Earthquake magnitude earthquake severity richter magnitude earthquake effects less than 3. A fault is a fracture or zone of fractures between two blocks of rock. Its like when youre teacher loses their marbles because youve asked them the same question 7 times in a row. Finally, when the plate has moved far enough, the edges unstick on one of the faults and there is an earthquake. Active faults at the base of the sierra nevada mountain range and within the basins to the east have caused damaging earthquakes in the past, such as the 1872 owens valley earthquake.
Scientists identify four types of faults characterized by the position of the fault plane, the break in the rock. The faults shown on the map have been sources of large earthquakes about magnitude 6. Earthquake faults the alquistpriolo earthquake fault zoning act prohibits building for human occupancy astride active faults. Founded in 1835, the njgs has evolved from a mineral resources and topographic mapping agency to a modern environmental organization that collects and provides geoscience information to government, consultants, industry, environmental groups, and the public. California laws relating to earthquake damage and repair to existing homes along active faults have put an extra financial burden on residents along the fault zone. Strikeslip faults are the source of many of the moderate to large earthquakes 4. The epicenter is the point on earths surface directly above the focus. In california, ground shaking causes 99% of earthquake damage to homes. Nov 16, 2016 types of faults a fault is a fracture or zone of fractures between two blocks of rock blocks move relative to each other along the fault plane may occur rapidly, in the form of an earthquake or may occur slowly may range in length from a few millimeters to thousands of kilometers. The movement of earths crust resulting from the release of built up potential energy between two stuck tectonic plates. On the other hand, the intervals of active fault earthquakes, which occur at inland active faults, range from a thousand to tens of thousands of. This map shows earthquakes known to have occurred within and surrounding utah from 1850 through december 2016 and mapped quaternary faults considered to be earthquake sources. The analysis of the sar interferograms led to the interpretations that the event was a blind thrust and did not produce surface ruptures associated with the.
Since the edges of the plates are rough, they get stuck while the rest of the plate keeps moving. When an earthquake occurs on one of these faults, the rock on one side of the fault slips with respect to the other. During an earthquake, the rock on one side of the fault suddenly slips with respect to the other. Nation except for connecticut, delaware, and rhode islandregistered the earthquake. Most faults produce repeated displacements over geologic time. Oct 15, 2014 next we introduce you to the hanging wall and footwall of faults and provide a brief assessment to allow you to practice using the terms.
Lesson plans and activities indiana geological and water. Field trip to the calaveras and san andreas faults. The amount of ground motion is one measure of earthquake intensity. Earthquakes on faults like these may cause tsunamis in the puget sound region. Geomorphic features of active faults around the kathmandu. A is 10x more intense than b a is more intense than b richter magnitude does not measure intensity b is 0.
Next we introduce you to the hanging wall and footwall of faults and provide a brief assessment to allow you to practice using the terms. Earthquake probabilities are calculated by projecting earthquake rates based on earthquake history and fault slip rates. Isbn 0521652235 hardback isbn 0521655404 paperback 1. Faults and earthquakes lesson plans and activities. What is the relationship between faults and earthquakes. Movement along a fault can be horizontal, vertical, or both. Thousands of earthquake faults exist in california. To reduce load times, the list is not rendered for large queries. The mechanics of earthquakes and faulting christopher h. Faults may range in length from a few millimeters to thousands of kilometers. It was so large that it caused the entire earth to ring like a bell. The earthquake that devastated san francisco, california, in 1906 arose from the san andreas fault which might be linked to another major fault zone to the north.
Pdf when an earthquake occurs on a fault, the rock volume around the rupture undergoes changes in stress state, which are closely related with. Multiple choice questions for earthquakes chapter 16. This movement may occur rapidly, in the form of an earthquake or may occur slowly, in the form of creep. Can cause major damage to poorly constructed buildings over small regions.
A full definition of the term, however, would need to include a good deal more. Earthquake a has a richter magnitude of 7 as compared with earthquake bs 6. Earthquake fault zones are delineated by the state geologist and implemented by lead agencies through permitting, inspection and landuse planning activities. The fault surface can be vertical, horizontal, or at some angle to the surface of the earth. The shaking or trembling caused by the sudden release of energy. Faults allow the blocks to move relative to each other. Earthquakes result from sudden movements along faults, creating a release of energy. Soils in lowland areas away from major faults may be subject to liquefaction. The objective was to determine the location of active faults and their slip rates and earthquake recurrence intervals. The new jersey geological survey is a public service and research agency within the nj department of environmental protection. When an earthquake occurs on a fault, the rock on one side of the fault slips with respect to the other. Earthquakes occur on faults strikeslip earthquakes occur on strikeslip faults, normal earthquakes occur on normal faults, and thrust earthquakes occur on thrust or reverse faults.
Earthquakes and faults putting down roots in earthquake country. Some are known to have ruptured the ground surface during the recent geologic past defined as the last 11,000 years and are considered to be active under the states earthquake faultzoning law see below. Pdf earthquake and fault propagation, displacement and damage. An earthquake is a sudden, rapid shaking of the earth caused by the release of energy stored in rocks. Faults and earthquakes 1 of 5 faults and earthquakes lesson plans and activities. The fracture of the rock which causes a tectonic earthquake is the result, of elastic strains greater than the strength of the rock. Those faults that move in a horizontal direction or sideways will not result in a tsunami.
The result is expressed as the probability that an. The map is based on the most recent usgs models for the conterminous u. Earthquakes occur on faults that are preferentially located along plate boundaries. When a fault suddenly moves on land, you get an earthquake. All the homes in this neighborhood were built before modern earthquake laws were enacted. We apply all four of these new terms to classify dipslip. Public resources code, section 2621 and following sections, requires sellers of existing residences to disclose to potential buyers on a natural hazards disclosure form if the property is located in a designated fault zone. Loss of life in the turkish earthquake was greatest in the city of izmit, located close to the earthquake s epicenter. A fault is a break or fracture between two blocks of rocks in response to stress. California public resources code division 2, chapter 7. The deadly izmit earthquake struck northwest turkey on august 17, 1999, at 3 a. They compare the san andreas fault zone and the new madrid fault zone on the united states map. Because the crust is weak in this area, the faults are likely candidates for future movement. Earthquakes teacher notes and student activities ga.
In this faults worksheet, students use an earthquake reference sheet to find the numbers for a modified mercalli and richter scale. A fault is a region on earths surface that is broken into 2 pieces there can be three types of movement in these diagrams, the hanging wall is the side that moves up or down. In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rockmass movement. The surface where they slip is called the fault or fault plane. Faults can be grouped based on their relative movement into three types. Larger crustal faults, such as the seattle fault and southern whidbey island fault zone, can produce earthquakes up to magnitude 7. But if a fault suddenly moves in or near a body of water, you may get a tsunami in addition to the earthquake. The focus is the point on the fault surface where motion begins. Large faults within the earths crust result from the action of plate tectonic forces, with the largest forming the boundaries between the plates, such as subduction zones or. A fault is a thin zone of crushed rock between two blocks of rock, and can be any length, from centimeters to thousands of kilometers.
Earthquakes in eastern north america seldom have magnitudes greater than 5. Two of the biggest us earthquake faults might be linked. A fault is a thin zone of crushed rock separating blocks of the earths crust. The fault surface can be vertical, horizontal, or at some. Faults that represent a hazard of surface rupture are included in alquistpriolo earthquake fault zones. A map depiction of regulatory earthquake fault zones. Faults are blocks of earths crust that meet together. Njdep new jersey geological and water survey earthquake. Homeowners guide to earthquake safety disclosure source. Not every fault movement beneath the sea will produce a tsunami. The characteristic earthquake appears to be a fundamental aspect of the behavior of the wasatch and san andreas faults and may apply to many other faults as om authors view show abstract.
Earthquake hazard map showing peak ground accelerations having a 2 percent probability of being exceeded in 50 years, for a firm rock site. Student reference page student copy faults and earthquakes 2 of 7 fault a fracture in the earths crust where one side moves relative to the other. A fault is a fracture or crack in the rocks where one side has moved relative to the other figure 1. A fault is a break in the earths crust along which movement has taken place causing an earthquake. If you are using ie 8 or later, make sure you turn off compatibility view. The longest earthquake ruptures on strikeslip faults, like the san andreas fault 1857, 1906, the north anatolian fault in turkey, and the denali fault in alaska, are about half to one third as long as the lengths along subducting plate margins, and those along normal faults are even shorter. There is no upper or lower limit to the richter scale, but as a mat ter of historical fact, no magnitude greater than about 9. An earthquake is what happens when two blocks of the earth suddenly slip past one another. The 1964 great alaska earthquake and tsunamisa modern. Most faults in washington are a mix of a strikeslip fault and a thrust or reverse fault. Rupture of deep faults in the 2008 wenchuan earthquake and. Homes in areas near large active faults are more likely to feel severe shakingand experience damage than homes in other areas of the state. These faults extend into illinois and northern kentucky and are collectively known as the wabash valley fault system.
Over 14,000 residents of the region were killed as poorly constructed. Faults are features in the earths crust where rock periodically breaks and moves, releasing seismic energy and creating an earthquake. Faults can be centimeters to thousands of kilometers long. Earthquakes are the sudden shaking and vibrating of the earths crust as a result of a rapid release of energy when rocks break and move along faults. This is a brief definition which students of all ages can master. Earthquakes on shallow faults typically last 20 to 60 seconds and the shaking is localized to the general area of the fault.624 66 244 603 816 1010 583 147 1472 246 625 1509 439 1153 999 398 202 924 124 1414 1419 1447 1530 586 16 1220 327 116 1090 1154 512 1010 1140 1313