41. Stick Slip Movement Along Seismic Faults on the fault, the crushing of rock, and the propagation of earthquake waves. Takecare to keep the dowel in the same position during rolling and measurement. http://tremor.nmt.edu/stick-slip.htm

A lesson form FEMA/AGU earthquake curriculum for teachers of grades 7-12. Unit 2.1 Stick-Slip Movement This section is intended to help students observe how stick-slip movement works. Instructions on how to build a motorized version of the following experiment as well as data produced from this model are available. Motorized version "Can Earthquakes Be Predicted?" Some background information Activities page What Happens When the Earth Quakes? Unit 2 begins with a hands-on activity that models what happens when the stresses accumulated at a fault are released in an earthquake. Using a box, a board, sandpaper, and other simple materials, students apply scientific method and basic math skills to measure movement, calculate averages, and plot their information on a graph. The third lesson begins with an exercise in which students contrast the small scope of historic time with the vastness of geologic time. In the second activity, Paleoseismology, they simulate the techniques seismologists use to read the record of relatively recent earthquakes. The amount of damage an earthquake causes depends on the strength and duration of the earthquake, on population density, on methods of construction (to be dealt with in Unit 4), and on the geophysical/geological characteristics of the impacted area. Lesson 4 progresses to three of the most potentially destructive earthquake effects: liquefaction, landslides, and tsunami. Each occurs when a seismic shock impacts an area with certain physical characteristics. Lesson 5 underlines the importance of site, as students interpret maps highlighting different features of the landscape. They will draw on their new knowledge to make additions to the local map they began in Unit 1.

42. EQ: Causes And Measurements the scale most commonly reported when referring to the size of an earthquake, ithas been found that for larger earthquakes a more accurate measurement of size http://www.tulane.edu/~sanelson/geol204/eqcauses.htm

EENS 204 Natural Disasters Tulane University Prof. Stephen A. Nelson Earthquakes: Causes and Measurements Most earthquakes occur along zones where the Earth's crust is undergoing deformation. Deformation results from plate tectonic forces and gravitational forces. The type of deformation that takes place during an earthquake generally occurs along zones where rocks fracture to produce faults. Before we can understand earthquakes, we first must explore deformation of rocks and faulting. Within the Earth rocks are constantly subjected to forces that tend to bend, twist, or fracture them. When rocks bend, twist or fracture they are said to deform or strain (change shape or size). The forces that cause deformation are referred to as stresses. To understand rock deformation we must first explore stress and strain. Stress and Strain Stress is a force applied over an area. One type of stress that we are all used to is a uniform stress, called pressure. A uniform stress is where the forces act equally from all directions. In the Earth the pressure due to the weight of overlying rocks is a uniform stress and is referred to as confining stress . If stress is not equal from all directions then the stress is a differential stress. Three kinds of differential stress occur. Tensional stress (or extensional stress) , which stretches rock;

43. EarthquakeWQ 1. Is there a measurement scale for earthquake strength and what isit called? 2. How is the strength of an earthquake measured? http://www.angelfire.com/pa5/broadstreetlibrary/earthquakeWQ.htm

var cm_role = "live" var cm_host = "angelfire.lycos.com" var cm_taxid = "/memberembedded" EARTHQUAKE!! WebQuest Created By: Mrs. K. Santillo, Library Media Specialist Butler Area School District Butler, PA Introduction Task Process Resources ... Conclusion Introduction: Each year, earthquakes cause millions of dollars in damages in the United States and around the world, and injure or kill thousands of people. Knowing what causes earthquakes, where they occur, and how to protect yourself can make a difference in your safety if you happen to live where earthquakes occur. Task: You and your family live in another country but are planning to move to the United States. The country where you live does not have earthquakes, but you have seen news reports that show earthquakes in the United States and the damage they cause. You each decide you want to investigate where and how earthquakes happen before picking the state you would like to live in. Process: Here are the questions you want to answer. 1. Where do earthquakes happen? 2. What causes earthquakes?

44. About Earthquakes ground. How are earthquakes Measured? Geologists conditions. The secondmethod of measurement is the magnitude of the earthquake. Magnitude http://www.seaint.org/seaoscnew/Public/about_earthquakes.htm

Email Ask SE Search About Earthquakes What is an Earthquake? An earthquake is the release of stress from the Earth's tectonic plates. The zone where two tectonic plates come together is called a fault. Prior to an earthquake, tectonic forces result in a gradual buildup of strain energy stored on either side of the fault. When the local stresses along the fault become too large, the fault slips suddenly or ruptures and releases the stored strain energy. This rupture on the fault plane is called the focus and the projection of this point on the ground surface is called the epicenter. When a rupture occurs along a fault, the strain energy stored on either side of the fault is released in the form of seismic waves and heat. These seismic waves propagate away from the ruptured fault zone and through the geologic layers of rock and soil. The process of seismic wave propagation causes the ground to shake. What Types of Earthquakes are there? The most common form earthquake is a shallow event where two tectonic plates slide past one another. Deeper earthquakes usually occur when one plate dives under another plate. Other earthquakes can also occur as a result of volcanic activity, collapses of the ground, and man-made explosions. What Types of Seismic Waves are Generated?

45. SEISMIC TERMS GLOSSARY Moment (of earthquake) measurement of an earthquake s size than is obtained bymultiplying the rigidity of the rock by the area of the fault and the amount http://rmsismo.uprm.edu/English/SeismicInformation/SeismicNotes/SN5pag1.html

SEISMIC NOTES INFORMATIVE BULLETIN OF THE PUERTO RICO SEISMIC NETWORK No. 5 - 1998 SEISMIC TERMS GLOSSARY* Accelerometer - Instrument to measure accelerations of the ground based on time. Active fault - Fault throughout which there has been displacement in historical times (Holocene) or where earthquake centers have been located (fig 1). After Shocks - Earthquakes smaller than follow the one greater one, concentrated in the zone of the main earthquake. Astenosphere Benioff Zone - narrow zone defined by the earthquake centers, of a thickness of tens of kilometers, that descends from the surface under the terrestrial crust. Cluster (of earthquakes) - A series of earthquakes of similar magnitude that happen in the same place. Crust (Earth's Crust) - the most external rocky part of the Earth; its thickness is about 5 to 40 km. Earthquakes - sudden and violent movement that originates in the crust or outer Earth mantle. Epicenter - the point of the Earth surface directly upon the center (or hypocenter) of an earthquake. Fault - a fracture or zone of rock fracture throughout which both sides have displaced. The total displacement can vary from centimeters to kilometers.

46. MSN Encarta - Earthquake This is because ground displacement of earthquake waves can range from less thana So, a magnitude 5 Richter measurement is ten times greater than a magnitude 4 http://encarta.msn.com/encyclopedia_761571674_3/Earthquake.html

MSN Home My MSN Hotmail Shopping ... Money Web Search: logoImg('http://sc.msn.com'); Encarta Subscriber Sign In Help Home ... Upgrade to Encarta Premium Search Encarta Tasks Find in this article Print Preview Send us feedback Related Items Fault, crack in Earth’s crust where earthquakes can happen Richter Scale, system for ranking earthquake size more... Magazines Search the Encarta Magazine Center for magazine and news articles about this topic Further Reading Editors' Picks Earthquake News Search MSNBC for news about Earthquake Internet Search Search Encarta about Earthquake Search MSN for Web sites about Earthquake Also on Encarta Editor's picks: Good books about Iraq Compare top online degrees What's so funny? The history of humor Also on MSN Summer shopping: From grills to home decor D-Day remembered on Discovery Switch to MSN in 3 easy steps Our Partners Capella University: Online degrees LearnitToday: Computer courses CollegeBound Network: ReadySetGo Kaplan Test Prep and Admissions Encyclopedia Article from Encarta Advertisement Page 3 of 3 Earthquake Multimedia 16 items Article Outline Introduction Anatomy of an Earthquake Causes Distribution ... Extraterrestrial Quakes B Emergency Preparedness Plans Earthquake education and preparedness plans can help significantly reduce death and injury caused by earthquakes. People can take several preventative measures within their homes and at the office to reduce risk. Supports and bracing for shelves reduce the likelihood of items falling and potentially causing harm. Maintaining an earthquake survival kit in the home and at the office is also an important part of being prepared.

47. Earthquake Engineering Research Laboratory Home Page vibrations, dynamics, machinery vibration, fluidstructure interaction, non-linearsystem identification, measurement and modeling of earthquake ground motion http://www.eerl.caltech.edu/

Earthquake Engineering Research Laboratory California Institute of Technology Wilfred D. Iwan , Director General Information Facilities Earthquake Engineering Research Library Faculty ... Links to Other Sites General Information Earthquake engineering activities at Caltech are conducted within the organizational structure of the Earthquake Engineering Research Laboratory (EERL). The laboratory was formed in the 1960's and has a long and distinguished history of being at the forefront of earthquake engineering research. Funding for EERL research activities comes from a variety of sources including federal and state government agencies and private companies. The faculties of the Earthquake Engineering Research Laboratory and the Seismological Laboratory of Caltech jointly conduct a program called the Earthquake Research Affiliates (ERA). This program provides regular research conferences and earthquake related field trips for member organizations. In addition to the joint efforts under the ERA program, the faculties of the two laboratories collaborate on numerous research projects. For information on EERL or NISEE, please contact:

48. Scales Of Measurement ground. Measured on a scale of I to XII, these measurements differdepending on the distance from the focus of the earthquake. The http://www.fcs-net.com/biddled/scalesof.htm

To measure the intensity of an earthquake, scientists have devised two scales, the Richter scale, which is named after the American seismologist Charles Francis Richter, and the Mercalli scale, which was introduced at the turn of the twentieth century by the Italian seismologist Giuseppe Mercalli. The Richter scale measures the amount of energy released at the focus, or starting point, of the earthquake. This scale has values from one to nine, with one being the least damaging. Each number indicates that the earthquake was ten times more powerful than the number before it. That would make an earthquake with a value of nine, one billion times more powerful than a magnitude one earthquake and one hundred thousand times more powerful than an atomic bomb. In the course of one year it is estimated that eight hundred earthquakes of a magnitude five to six will occur, in comparison, 50,000 earthquakes of a magnitude of three to four, and approximately only one with a magnitude of eight or nine will occur. The Mercalli scale measures the intensity of the shaking of the ground. Measured on a scale of I to XII, these measurements differ depending on the distance from the focus of the earthquake. The levels of this scale range from imperceptible shaking to mass destruction. Instead of having a mathematical basis, this scale is based on observed effects.

49. New Technology To Help Measurement And Study Of Earthquakes The continuous, earthquakerelated measurements from the GPS network will allow scientiststo make a high-precision survey of the southern California terrain. http://www.geo.nsf.gov/geo/adgeo/press/pr9667.htm

New Technology to Help Measurement and Study of Earthquakes Media contact: Cheryl Dybas NSF 96-67 October 30, 1996 All others contact: Jim Whitcomb Scientists have begun installing a network of 250 Global Positioning System (GPS) receivers that will continuously measure the constant, yet physically imperceptible, movements of earthquake faults throughout southern California. This information should help researchers forecast future earthquake hazards in the greater Los Angeles area. "GPS is the most important new technology to emerge for the study of earthquakes in decades," says Tom Henyey, director of the Southern California Earthquake Center (SCEC) in Los Angeles, a National Science Foundation Science and Technology Center. "This information will allow us to improve our estimates of the regional earthquake hazard in southern California and to prioritize earthquake mitigation activities, including emergency preparedness and retrofit strategies. Continuous GPS measurements will also allow for more rapid regional damage assessment after large earthquakes." GPS is a constellation of 24 Earth-orbiting satellites, arranged so that several are "visible" from any point on the surface of the Earth at any time. A user on the ground with a GPS receiver can determine his or her precise location by measuring signals from the GPS satellites.

50. Maryland Geological Survey: Earthquakes In Maryland MEASURING earthquake. measurement of the severity of an earthquake can be expressedin several ways, the two most common being intensity and magnitude. http://www.mgs.md.gov/esic/brochures/earthquake.html

Pamphlet Series Earthquakes and Maryland contact: Dale Shelton ( dshelton@mgs.md.gov Maryland's earthquake monitoring network is online. Visit the Seismic Network Pages for more information, and see live seismic displays. You can download a PDF version of this brochure, suitable for printing. Click here to get mdquakes.pdf By James P. Reger INTRODUCTION Earthquakes can be among the most devastating and terrifying of natural hazards. Although floods, tornadoes and hurricanes account for much greater annual loss in the United States, severe earthquakes pose the largest risk in terms of sudden loss of life and property. There are many interrelated factors that determine the extent of loss of property and life from an earthquake. Each of the following should be prefaced with "other factors being equal. . . ." Amount of seismic energy released: The greater the vibrational energy, the greater the chance for destruction. Duration of shaking: This is one of the most important parameters of ground motion for causing damage. Depth of focus, or hypocenter: The shallower the focus (the point of an earthquake's origin within the earth), usually the greater the potential for destructive shock waves reaching the earth's surface. Even stronger events of much greater depth typically produce only moderate shaking at ground level.

51. Wanganui District Council - Civil Defence: Earthquakes Richter Scale (measurement 1 9) This refers to the magnitude of an earthquakeand is a measurement of the energy liberated at its source. http://www.wanganui.govt.nz/civilDef/earthquake.html

Earthquakes Hundreds of earthquakes occur in New Zealand each year. Many of them are so deep that only a few cause damage and injury. However, a severe earthquake could occur at any time. Wanganui Earthquake History Liquefaction may occur in susceptible areas and increase the risk of subsidence. Liquefaction is where the earth loses the ability to support weight when groundwater rises with an earthquake. A map showing liquefaction areas in Wanganui is available from Civil Defence. What you can do to help yourself Before an earthquake occurs: Secure heavy furniture to the wall or floor. Place heavy items on bottom shelves or on the floor. Put strong catches on cupboards. Check your chimney is secure. Secure your hot water cylinder and header tank (if you have one). Check that your household insurance covers earthquake damage. Assemble your survival kit items and ensure everyone in your household knows where your kit is kept. Join a Neighbourhood Support Group . Your best help will be a friendly neighbour. During an earthquake, if you are inside:

52. Earthquake, Blast And Impact: Measurement And Effects Of Vibration earthquake, Blast and Impact measurement and Effects of Vibration,Seced,Spon,Societyfor earthquake Civil Engineeri. http://www.civilbookstore.com/index/book/1851667059.html

Home Calculators Handhelds Software ... Tools The lowest priced and most extensive civil engineering bookstore on the Internet. View Cart Home Help About Us Keyword Author ISBN Advanced Search Architectural Engineering Bridge Engineering Construction ... Transportation Engineering Enter your Name and E-mail address below to receive our monthly civil engineering newsletter. Name: E-mail: Earthquake, Blast and Impact: Measurement and Effects of Vibration Author(s): Seced Spon Release Date: April, 1998 Availability: Usually ships within 24 hours List Price: Our Price: Product Details: Hardcover ISBN: 1851667059 Sales Rank: 2,673,333 Have one to sell? back to top All brands, company, or product names or trademarks belong to their respective holders. BOSS International Legal Notices Privacy Statement

53. Earthquake Intensity This method can be used by seismologists all over the world who can come up witha magnitude measurement within minutes of the earthquake being recorded. http://www.em.gov.bc.ca/Mining/Geolsurv/Surficial/quake/eq2.htm

Earthquake Intensity Damage from the 1946 Quake Earthquake Intensity Glossary How can geology be used to minimize risk? What are the effects of earthquakes? What causes earthquakes? ... Where do earthquakes occur? How big are earthquakes? The size of an earthquake can be measured in two ways. The intensity measures the destructiveness of the quake while the magnitude measures the energy released by the quake. Earthquake Intensities The intensity of an earthquake is a measure of the destructive effects of the quake at the surface. It is measured on an arbitrary scale of 12 degrees modified from an original scale devised by the Italian seismologist Giuseppe Mercalli. The scale uses information supplied by people living in the area of the quake. The Modified Mercalli Intensity Scale Intensity Description Characteristic effects I Instrumental Not felt by people, only detected by seismographs. II Feeble Felt only by a few people at rest, especially on upper floors of buildings. Delicately suspended objects may swing. III Slight Felt noticeably indoors; like the vibrations due to a passing truck. Standing motor cars may rock slightly.

54. Demo #7: Earthquake Location the class into groups of three or four students each, with one earthquake per group Swave arrival (they can use the string to transfer this measurement to the http://www.geol.binghamton.edu/faculty/barker/demos/demo7.html

Demo #7: Earthquake Location Purpose: Demonstrates earthquake location using triangulation on a globe. Supplies: Seismograms (at least three), travel-time curves, string, globe Background and Demonstration: Since P waves travel faster than S waves, the time difference between the arrival of the P wave and the arrival of the S wave depends on the distance the waves traveled from the source (earthquake) to the station (seismograph). Over time, many such measurements have been made, and travel-time curves (time vs. distance plots for P, S and other more complicated waves) have been developed for the Earth. If an earthquake occurred a given distance from a station, it could have been anywhere on a circle whose radius is that distance, centered on the station. If distances from two stations are known, two locations are possible: the two intersection points of two circles. If distances from three stations are known, the earthquake can be unambiguously located. This is the principle of triangulation. Earthquake location through triangulation is often demonstrated on a map. However, unless the earthquake and station locations are chosen very carefully, the map projection distorts distances and the directions the waves have traveled. This can raise more questions than it answers. Therefore I suggest using a globe. Also, if a source of current seismograms is available (see below), students really enjoy the sense of discovery of locating an earthquake of current interest.

55. Alan L. Jones Instrumentation measurement, IM21, 11 Jones, Richard H., Alan L. Jones (2004) TestingSkill in earthquake Predictions, Seismological Research Letters, 74, 753 http://www.geol.binghamton.edu/faculty/jones/jones.html

Alan L. Jones Research Scientist PhD (1964) Purdue University Science 1, G60B, (607) 777-2518 jones@geol.binghamton.edu Contents Research Interests Education Background Computer Programs ... Publications Research Interests: Seismology Wave propagation Evaluation of earthquake predictions Computer graphics Use of computers in seismology Seismicity Computers in education Education B.S. Engineering Sciences, Penn State, 1958 M.S. Engineering Mechanics, Penn State, 1960. Ph.D. Engineering Sciences, Purdue, 1964. Thesis: Wave propagation in optical fibers. Background After finishing my degree at Purdue University in November 1963, I joined IBM at the Glendale Development Laboratory in Endicott New York. During my 26 years with IBM I worked on: IBM Blood Cell Separator and IBM Blood Cell Processor. Co-author of IBM's APL graphics offering known as GRAPHPAK Device attachment Computer packaging When I took an early retirement in 1990 from IBM I joined the staff at the State University of New York at Binghamton working with Francis Wu and Jeff Barker. Computer Programs: Seismic/Eruption: A program for the visualization of seismicity and volcanic activity in space and time.

56. Measurement Of Topographic Variation By Hyogo-Nanbu Earthquake With JERS 1STAR I ACRS 1995 Mapping from Space; measurement of Topographic variationby HyogoNanbu earthquake with JERS 1STAR Interferometry. http://www.gisdevelopment.net/aars/acrs/1995/ts3/ts3002.shtml

Home Site Map Subscribe Newsletters Search The Site ... ACRS Sessions Plenary Session Forest / Vegetation Mapping Agriculture/Soil Mapping from Space ... Workshop on Spatial Information Processing Poster Sessions Poster Session 1 Poster Session 2 Poster Session 3 Poster Session 4 ACRS 1995 Mapping from Space Printer Friendly Format Page 1 of 2 Next Measurement of Topographic variation by Hyogo-Nanbu Earthquake with JERS 1STAR Interferometry Yuichi Maruyama, Hiroji Tsu Earthquake Remote Sensing Data Analysis Center (ERSDAC) Forefront Tower, Kachidoki 3-12-1, Chuo-ku, Tokyo, JAPAN Tel. 03-3533-9380,fax. 03-3533-9383 1. Introduction The Hyogo-Nanbu Earthquake occurred on 17 January 1995 attacked the Kobe city and the Awaji island. More than 5,000 of human lives were lost under the collapsed houses and a fire. The fault activity was observed on the several points in the area after the occurrence. The fault displacements were measured in many places. The deformation of the topographic surface, however, was hardly measured on the surrounded area of the fault line. The purpose of this study is to know the availability of the interferometric SAR for the deformation of topographic surface, by the earthquake with JERS-1 SAR data. Because, it can be very useful information for the study of active geological structure. In addition, it is also possible to apply for the natural disaster focusing such as landslide, volcanic hazards, etc.

57. Earthquake Damages Neighboring Fault, UCLA And USC Scientists Report four measurements from the five years before the Hector Mine earthquake that revealedprogressive recovery each time stronger than the previous measurement. http://www.sciencedaily.com/releases/2003/02/030203071747.htm

Match: sort by: relevance date Free Services Subscribe by email RSS newsfeeds PDA-friendly format loc="/images/" A A A Find Jobs In: Healthcare Engineering Accounting College Contract / Freelance Customer Service Diversity Engineering Executive Healthcare Hospitality Human Resources Information Tech International Manufacturing Nonprofit Retail All Jobs by Job Type All Jobs by Industry Relocating? Visit: Moving Resources Moving Companies Mortgage Information Mortgage Calculator Real Estate Lookup Front Page Today's Digest Week in Review Email Updates ... Outdoor Living Source University Of California - Los Angeles Date Print this page Email to friend Earthquake Damages Neighboring Fault, UCLA And USC Scientists Report The 1999 magnitude 7.1 Hector Mine earthquake, in the Mojave Desert near Los Angeles, damaged the fault that broke in the 7.3 magnitude Landers earthquake seven years earlier, report John Vidale, UCLA professor of earth and space sciences, and USC seismologist Yong-Gang Li, in the Jan. 30 issue of the journal Nature. What's Related Earthquake Studies: Fault Moving Faster Than Believed Hidden, Quake-Prone Fault Confirmed Under Los Angeles

58. Macroseismic Methods This is a measurement, or rather a classification, of the strength of shaking ofan earthquake at a particular place, based on the observations made of the http://www.quakes.bgs.ac.uk/hazard/macmeth.htm

MACROSEISMIC METHODS The fundamental concept in macroseismology is earthquake intensity . This is a measurement, or rather a classification, of the strength of shaking of an earthquake at a particular place, based on the observations made of the different effects. The procedure is very similar to that for measuring wind strength with the Beaufort Scale. An intensity scale provides a series of idealised descriptions of the effects of an earthquake, starting with the very weakest (the shaking is imperceptible) up to the very strongest (everything is totally destroyed). The seismologist collects observations from ordinary people and attempts to match them to the descriptions in the intensity scale. If the effects from a certain place best match the description for degree 5 of the scale, then intensity 5 is assigned for that place. It's simple, low-tech, and surprisingly effective. The stages of a macroseismic investigation are something like this: (i) The earthquake happens. The seismologist quickly tries to get an estimate of the total area likely to have been affected by the earthquake. This may be estimated from the size (magnitude) of the earthquake, or from information received via telephone calls from the public and from police. (ii) The seismologist collects information from this area, usually by distributing a questionnaire that covers all the most important types of information he wants to get, eg, was there damage? If so, how bad was it? The questionnaire may be sent by post to selected individuals, or to schools, or public officials, or distributed by hand, or published in a newspaper - the method varies from country to country.

59. 1994 Building Publications - Full-Scale Measurement Of Building Response To Ambi FullScale measurement of Building Response to Ambient Vibration andthe Loma Prieta earthquake. Full-Scale measurement of Building http://fire.nist.gov/bfrlpubs/build94/art001.html

Full-Scale Measurement of Building Response to Ambient Vibration and the Loma Prieta Earthquake. Full-Scale Measurement of Building Response to Ambient Vibration and the Loma Prieta Earthquake. (536 K) Marshall, R. D.; Phan, L. T.; Celebi, M. Earthquake Engineering Research Institute. Earthquake Awareness and Mitigation Across the Nation. U.S. National Conference, Fifth (5th). Proceedings. Volume 2. July 10-14, 1994, Chicago, IL, 661-670 pp, 1994. Keywords: earthquakes; vibration; data analysis; high rise buildings; office buildings; commercial buildings Abstract: Building and Fire Research Laboratory National Institute of Standards and Technology Gaithersburg, MD 20899

60. USGS Earthquake Hazards Program-FAQ - Frequently Asked Questions can be estimated from seismograms (and also from geodetic measurements). The momentis then converted into a number similar to other earthquake magnitudes by a http://earthquake.usgs.gov/faq/meas.html

Latest Quakes For Kids Only Regional Websites HOME ... SEARCH Frequently Asked Questions FAQ Home Current EQs Myths EQs,Faults,etc ... Other Resources Measuring Earthquakes Q: Where can I buy a Richter scale? A: The Richter scale is not a physical device, but a mathematical formula. The magnitude of an earthquake is determined from the logarithm of the amplitude of waves recorded on a seismogram at a certain period. See next question and answer. For further information, see: The Richter Magnitude Scale Q: How are earthquakes recorded? How are earthquakes measured? How is the magnitude of an earthquake determined? A: Earthquakes are recorded by a seismographic network. Each seismic station in the network measures the movement of the ground at the site. The slip of block of rock over another in an EQ releases energy that makes the ground vibrate. That vibration pushes the adjoining piece of ground and cause it to vibrate and thus the energy travel out from the EQ in a wave. There are many different ways to measure different aspects of an earthquake. Magnitude is the most common measure of an earthquake's size. It is a measure of the size of the earthquake source and is the same number no matter where you are or what the shaking feels like. The Richter scale measures the largest wiggle on the recording, but other magnitude scales measure different parts of the earthquake.

A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z

Page 3     41-60 of 92    Back | 1  | 2  | 3  | 4  | 5  | Next 20