61. Richter Earthquake Scale Mercalli intensity is based upon observations of the resulting earthquakedamage and not actually measured on instruments. Invented http://mistupid.com/geology/richter.htm

Related Info: Beaufort Wind Scale Fujita Tornado Scale Geological Time Scale Hurricane Scale ... Roman Numerals Richter and Mercalli Earthquake Scale The Richter scale was created in 1935 by the American seismologist Charles F. Richter. It measures how much the ground shakes 60 miles from the earthquakes epicenter. Richter magnitudes increase logarithmically, meaning the energy increases 10 times for each magnitude number. Mercalli intensity is based upon observations of the resulting earthquake damage and not actually measured on instruments. Invented by Italian seismologist Giuseppe Mercalli. Richter Magnitude Mercalli Intensity Description I Usually not felt, but detected by instruments. II Felt by very few people. III Felt by many, often mistaken for a passing vehicle. IV Felt by many indoors, dishes and doors disturbed. V Felt by nearly everyone. People awakened. Cracked walls, trees disturbed. VI Felt by all. Many run outdoors. Furniture moves. Slight damage occurs.

62. FEMA: Earthquake Information The Richter Scale was developed by Charles F. Richter in 1935. It is a logarithmicmeasurement of the amount of energy released by an earthquake. http://www.fema.gov/hazards/earthquakes/quake.shtm

Hazards Assistance Flood Maps NPSC ... Hazards What is an earthquake? Search FEMA Hazards Dam Safety Earthquakes Extreme Heat ... Mitigation Division What is an earthquake? An earthquake is a sudden, rapid shaking of the Earth caused by the breaking and shifting of rock beneath the Earth's surface. For hundreds of millions of years, the forces of plate tectonics have shaped the Earth as the huge plates that form the Earth's surface move slowly over, under, and past each other. Sometimes the movement is gradual. At other times, the plates are locked together, unable to release the accumulating energy. When the accumulated energy grows strong enough, the plates break free causing the ground to shake. Most earthquakes occur at the boundaries where the plates meet; however, some earthquakes occur in the middle of plates. Ground shaking from earthquakes can collapse buildings and bridges; disrupt gas, electric, and phone service; and sometimes trigger landslides, avalanches, flash floods, fires, and huge, destructive ocean waves (tsunamis). Buildings with foundations resting on unconsolidated landfill and other unstable soil, and trailers and homes not tied to their foundations are at risk because they can be shaken off their mountings during an earthquake. When an earthquake occurs in a populated area, it may cause deaths and injuries and extensive property damage. The Northridge, California, earthquake of January 17, 1994, struck a modern urban environment generally designed to withstand the forces of earthquakes. Its economic cost, nevertheless, has been estimated at $20 billion. Fortunately, relatively few lives were lost. Exactly one year later, Kobe, Japan, a densely populated community less prepared for earthquakes than Northridge, was devastated by the most costly earthquake ever to occur. Property losses were projected at $96 billion, and at least 5,378 people were killed. These two earthquakes tested building codes and construction practices, as well as emergency preparedness and response procedures.

63. Earthquakes! Different methods of measuring magnitude have superseded the Richter Scale, includingsurfacewave on the size of the fault on which an earthquake occurs and http://www.infoplease.com/spot/earthquake1.html

HOTWORDS CITE PRINT EMAIL in All Infoplease Almanacs Biographies Dictionary Encyclopedia Home Almanacs Atlas Dictionary ... Father's Day Infoplease Tools Periodic Table Conversion Tool Perpetual Calendar Year by Year ... Site Map Also from Infoplease Search Infoplease Info search tips Search Biographies Bio search tips Earthquakes by Borgna Brunner There are thousands upon thousands of earthquakes annually, ranging on average from 18 major quakes to more than 2 million very minor ones per year (approximately 8,000 per day). On average, we can expect one exceptionally big one (with a magnitude of 8 or higher) each year. Earthquakes plate tectonics Earthquakes in residential areas, such as this 1964 one in Seward, Alaska, can cause unparalleled damage to life and property. Not "On the Richter Scale" Although "on the Richter Scale" is still a commonly used expression, the scale , developed by Charles F. Richter of California Institute of Technology in 1935, is no longer the most commonly used magnitude measurement . One of its flaws is its imprecision in measuring the biggest earthquakes, those in the range of 8 or 9. Different methods of measuring magnitude have superseded the Richter Scale , including surface-wave magnitude, which measures the seismic waves crackling around Earth's surface, and moment magnitude, the newest method, which is based on the size of the fault on which an earthquake occurs and the amount the Earth slips. Moment magnitude is the most uniformly applicable scale.

64. Glossary Of Terms: E Measurements indicate that the average Earth albedo is approximately30 %. earthquake Is a sudden motion or trembling in the Earth. http://www.physicalgeography.net/physgeoglos/e.html

GLOSSARY OF TERMS HOME FUNDAMENTALS ONLINE TEXTBOOK GLOSSARY ... Z Glossary of Terms: E Earth Albedo Is the reflectivity of the Earth's atmosphere and surface combined. Measurements indicate that the average Earth albedo is approximately 30 %. Earthflow A rapid type of downslope mass movement that involves soil and other loose sediments . Usually triggered by water saturation from rainfall. Earthquake Is a sudden motion or trembling in the Earth. The motion is caused by the quick release of slowly accumulated energy in the form of seismic waves . Most earthquakes are produced along faults tectonic plate boundaries, or along the mid-oceanic ridges Earthquake Focus Point of stress release in an earthquake Earth Revolution Refers to the orbit of the Earth around the sun . This celestial motion takes 365 1/4 days to complete one cycle. Further, the Earth's orbit around the sun is not circular, but elliptical.

65. Modified Mercalli Intensity Of the two ways to measure earthquake size, magnitude based on instrumental readingsand intensity based on qualitative effects of earthquakes, only intensity http://www.eas.slu.edu/Earthquake_Center/mercalli.html

Earthquake Intensity Of the two ways to measure earthquake size, magnitude based on instrumental readings and intensity based on qualitative effects of earthquakes, only intensity can be applied to pre-instrumental earthquakes. The 1931 Modified Mercalli scale used in the United States assigns a Roman numeral in the range I - XII to each earthquake effect. The methodology is simple. At each location assign a numeral to describe the earthquake effect Contour the zones of similar effect The earthquake is assumed to have occurred near the region of maximum intensity The earthquake may be characterized by the largest Roman numeral assigned to it The problems with intensity are multifold. First, it is a qualitative assessment that measures different phenomena. The lower values address human response to ground motions, the intermediate values characterize the response of simple structures, and the upper values describe ground failure processes. Another problem is that incomplete spatial coverage may lead to a mislocation of the earthquake or an underassessment of its size. This is easily visualized for offshore earthquakes or, in the case of the United States, inadequate population distribution at the time of the earthquake. Modified Mercalli Scale Average peak velocity (centimeters per second) Intensity value and description Average peak acceleration (g is gravity=9.80 meters per second squared)

66. Measuring Earthquake Magnitudes Earthquakes, in fact, are very hard to measure. The problem is like comingup with one number to indicate the quality of a baseball pitcher. http://geology.about.com/cs/quakemags/a/aa060798.htm

zJs=10 zJs=11 zJs=12 zJs=13 zc(5,'jsc',zJs,9999999,'') About Homework Help Geology Home ... Plate Tectonics in a Nutshell zau(256,152,180,'gob','http://z.about.com/5/ad/go.htm?gs='+gs,''); Maps Rocks and Sediments Geology and Culture Geophysics ... Help zau(256,138,125,'el','http://z.about.com/0/ip/417/0.htm','');w(xb+xb); Stay Current Subscribe to the About Geology newsletter. Search Geology Email to a friend Print this page Stay Current Subscribe to the About Geology newsletter. Suggested Reading Earthquake Intensity More Earthquake Articles Site Content A - Z Elsewhere on the Web Charles Richter bio The Original Richter Scale Hiroo Kanamori's site Most Popular Geology Image Gallery - Geologic Features and Processes Zen Rock Garden About Geology Image Gallery - The Rock Wing Global Seismic Hazard Map Index ... Geology Content, A to Z What's Hot The Bogeyman of Earthquake Prediction The Century in Review: Asbestos Tombolo Rock Identification Tables ... Getting to the Core Earthquake Magnitudes From Andrew Alden Your Guide to Geology Sign up for my Newsletter Measuring the Big One Earthquakes, in fact, are very hard to measure. The problem is like coming up with one number to indicate the quality of a baseball pitcher. You can start with the pitcher's win-loss record, but the more you study the problem the more things you want to consider, like earned-run average, defensive range, strikeouts and walks, career longevity, and so on. Baseball statisticians love to tinker with indexes that weigh as many of these factors as possible. (And if you want to know more, visit the

67. FAQs On Pacific Northwest Earthquakes 6), major (magnitude 7). The Richter magnitude of an earthquake is calculated bymeasuring the amplitude of the maximum wave motion recorded on the seismogram. http://www.geophys.washington.edu/SEIS/PNSN/INFO_GENERAL/faq.html

The Pacific Northwest Seismograph Network All about earthquakes and geologic hazards of the Pacific Northwest HOME Latest Quakes Volcanoes Research ... CONTACT US Frequently Asked Questions Earthquakes in Washington and Oregon Where are the major faults in the Pacific Northwest? Are there faults near Seattle and Portland? Why does the Pacific Northwest have earthquakes? How often do earthquakes occur in the Pacific Northwest? ... There seems to be a lot of activity on the Webicorders, but there are not any events listed on the "Recent Events" list. What is going on? General Questions About Earthquakes What are the different kinds of faults? What are foreshocks and aftershocks? What's the difference between an M 4 and an M 6 earthquake? What is a tsunami? ... Return to Seismology Page Q: Where are the major faults in the Pacific Northwest? A: There are many faults in the Pacific Northwest that can produce damaging earthquakes, including hard-to-identify faults that exist entirely underground and have not been identified at the earth's surface. At the same time, some mapped faults have been located that have not generated earthquakes in recent geologic time. New faults continue to be discovered as more field observations and earthquake data are collected. There are three different sources for damaging earthquakes in the Pacific Northwest. The first of these is the "Cascadia Subduction Zone", a 1000 km long thrust fault which is the convergent boundary between the Juan de Fuca and North American plates and is the most extensive fault in the Pacific Northwest area. It surfaces about 50 miles offshore along the coasts of British Columbia, Washington, Oregon and northern California. No historic earthquakes have been directly recorded from this source zone. According to recent research, an earthquake estimated to be as large as 8.0 to 9.0 occurred in this zone in January of 1700.

68. How Do Scientists Measure Earthquakes? many earthquakes in southern California, and realized that some earthquakes madevery 100 km from the epicenter when you make the measurement; otherwise, all http://tremor.nmt.edu/how.html

How do scientists measure earthquakes? With a really big ruler? No, not quite. There are two ways in which scientists quantify the size of earthquakes: magnitude and intensity. Magnitude is a measure of the amount of energy released during an earthquake, and you've probably heard news reports about earthquake magnitudes measured using the Richter scale. Something like, "A magnitude 7.3 earthquake struck Japan today. Details at ten." Did you ever wonder why, if it's that important, they just don't tell you right away? The Richter scale was invented, logically enough, in the 1930s by Dr. Charles Richter , a seismologist at the California Institute of Technology. It is a measure of the largest seismic wave recorded on a particular kind of seismograph located 100 kilometers (about 62 miles) from the epicenter of the earthquake. Think of a seismograph as a kind of sensitive pendulum that records the shaking of the Earth. The output of a seismograph is known as a seismogram. In the early days, seismograms were produced using ink pens on paper or beams of light on photographic paper, but now it's most often done digitally using computers. The seismograph that Dr. Richter used amplified movements by a factor of 3000, so the waves on the seismograms were much bigger than those that actually occurred in the Earth. The epicenter of an earthquake is the point on the Earth's surface directly above the source, or focus, of the movement that causes the quake. Dr. Richter studied records from many earthquakes in southern California, and realized that some earthquakes made very small waves whereas others produced large waves. So, to make it easier to compare the sizes of the waves he recorded, Richter used the logarithms of the wave heights on seismograms measured in microns (1/1,000,000th of a meter, or 1/1000th of a millimeter). Remember, you have to be using a particular kind of seismograph located 100 km from the epicenter when you make the measurement; otherwise, all sorts of complicated calculations have to be made. That's why seismologists spend so many years in college!

69. MEASURING EARTHQUAKES WEBQUEST For a better understanding of earthquakes you will be asked to answer a few questionsabout the measurement itself and will have to built a machine called a http://www.cqsb.qc.ca/docs/webquest/quake.htm

MEASURING EARTHQUAKES WEBQUEST by Caro, Denise and Vero La Tuque High School, 1999 Introduction Earthquakes are measured with numbers from 1 to 9. You will discover why and how these numbers are related. Task For a better understanding of earthquakes you will be asked to answer a few questions about the measurement itself and will have to built a machine called a seismograph. Resources http://www.backgroundbriefing.com/earthqke.html http://www.backgroundbriefing.com/earthqke.html http://agcwww.bio.ns.ca/schools/quakes/dehler_7a.html http://psn.quake.net/cgi-dos/event.exe Book: "The Amateur scientist", Scientific American, July 1957 and July 1979: basic principles and how to built a simple seismograph. Process With two of your friends, answer on a separate sheet of paper. (go to: http://www.backgroundbriefing.com/earthqke.html http://agcwww.bio.ns.ca/schools/quakes/dehler_7a.html http://psn.quake.net/cgi-dos/event.exe did the latest earthquake occur? (go to: http://www.kpbsd.k12.ak.us/mtn.view/Cfk/earthquake/Fissures/cassieseismo.html Evaluation Did every participant have a chance to work on the Quest?

70. Roger Bilham's Homepage (Last revision Jan 1999). Venezuela 19921999 GPS measurements across theSE Caribbean plate boundary include slip during the Cariaco earthquake. http://cires.colorado.edu/~bilham/

Earthquakes and Tectonic Plate motions Roger Bilham, University of Colorado Geology 1010 Spring 2004 Final grades were posted to the University System 7 May 2004 Geophysics 4130 Spring 2004 Grading 7 May awaits answers concerning some late end of term papers Publications IRIS/SSA Distinguished Lectureship talk (html ), or Power-point (!beware 17Mb file Department of Geological Sciences, 2200 Colorado Avenue, University of Colorado, Boulder CO 80309-0399 USA FAX 303 492 2606 Phone 303 492 6189 email: bilham@stripe.colorado.edu New NSF biaxial tiltmeters near Seattle Data from tiltmeters near Mammoth Lakes in the Long Valley Caldera (US Geological Survey) are available subject to telemetry and power outages. Anomalous tilt near Mammoth Lakes in Long Valley 13-16 October 1998 was apparently caused by aseismic dip-slip on a graben bounding fault near the tiltmeter - the only known example of a slow normal earthquake. Creep Measurements in California Incoming crustal deformation data may be viewed from creepmeters on the Hayward Fault in the Bay Area of San Francisco, Of the five creepmeters on the Hayward fault the creepmeter at Fremont alone exhibits episodic creep events. The creep rate on the northern Hayward Fault has been approximately linear despite a local M=4 earthquake near Berkeley in December '98 -see

71. WA Earthquake Hazards - How Are Earthquakes Measured? 8). Figure 6 shows how the Richter magnitude of an earthquake is calculated by measuringthe amplitude of the maximum wave motion recorded on the seismogram. http://www.pnsn.org/INFO_GENERAL/NQT/how_are.html

Next section Previous section Table of Contents Pacific Northwest Earthquakes HOW ARE EARTHQUAKES MEASURED? taken from "Washington State Earthquake Hazards", by Linda Noson, Anthony Q amar, and Gerald Thorsen Figure 6 shows how the Richter magnitude of an earthquake is calculated by measuring the amplitude of the maximum wave motion recorded on the seismogram. The intensity of an earthquake is a measure of the amount of ground shaking at a particular site, and it is determined from reports of human reaction to shaking, damage done to structures, and other effects. The Modified Mercalli Intensity Scale ( Table 1 ) is now the scale most commonly used to rank earthquakes felt in the United States. If magnitude is compared to the power output of a radio broadcasting station, then the intensity of an earthquake is the signal strength at a particular radio receiver. In practice, an earthquake is assigned one magnitude, but it may give rise to reports of intensities at many different levels. The magnitude 6.5 April 29, 1965, Seattle-Tacoma earthquake produced intensity VII to VIII damage near its epicenter, intensity V damage 150 kilometers away, and intensity I and 11 (barely felt) 300 to 500 kilometers from the epicenter ( Figure 7 ). Although the greatest damage, and thus highest intensity, is usually near the earthquake's origin, damage to buildings depends on many factors, such as the type of construction, distance from the epicenter, and type of soil beneath the building. (See Structural Failure of Buildings, in the section titled What Causes Damage?) Therefore, maps of earthquake intensity commonly show complex patterns.

72. Activity #3 -- Measuring Earthquakes this activity is to learn how analysis and measurement of seismograms mathematicalcalculations, yield the map locations the epicenters of earthquakes. http://www.data.scec.org/Module/s3act03.html

Section 3: Measuring Earthquakes Activity #3: LOCATING EARTHQUAKES Concept: Both the epicenter and origin time of an earthquake can be located with computations involving the exact arrival times of seismic waves at three or more seismometers. These arrival times can be picked by analyzing the waveforms recorded on seismograms. Materials: a frames- and layers-capable browser online guide to using this activity Locating Earthquakes activity page Procedure: The purpose of this activity is to learn how analysis and measurement of seismograms from three or more seismometers can, with relatively simple mathematical calculations, yield the map locations the epicenters of earthquakes. The online section of this activity will allow you to interactively analyze real seismic data from several earthquakes that have occurred in southern California. You will be picking the arrival times of the two body waves the P wave and the S wave and then, using travel-time circles on a map of southern California as your guide, marking the location you believe represents the epicenter of the earthquake. Your wave-arrival picks will also be used to calculate the origin time of the earthquake. Should your first attempt to pick the arrival times produce unsatisfactory results, you will be able to revise them, and see the changes in time and location produced by the changes in your picks. In fact, there is no limit to the number of times you can revise your analysis of the seismograms provided. This page will help you get started by previewing the basics of the activity. The

73. Nearctica - Geology - Earthquakes A good and comprehensive introduction to earthquakes with information on the differentkinds of earthquakes, their causes, detection and measurement, and more. http://www.nearctica.com/geology/quake/quake.htm

Earthquakes Special Segments Butterflies of North America Conifers of North America Eastern Birds List of N.A. Insects Home Eastern Wildflowers General Topics Natural History Ecology Family Environment Evolution Home Education Home Conservation Geophysics Paleontology Commercial Organizations Return to Geology Main Page Books About Earthquakes This page contains links to general sites on seismology and earthquakes. Be sure to visit the other pages in the earthquake section of geology as well. General Information. Recent and Current Earthquake Information Web Sites with Links to Seismology Historical Earthquakes ... Tsunamis GENERAL SEISMOLOGY SITES General Earthquake Information . National Earthquake Information Center. If you want to learn about earthquakes this is certainly the place to go. This magnificent site has a wealth of information. For example there are sections on frequently asked questions, the largest earthquakes in the United States and the world, information on how earthquakes are measured, the principle faults in the United States, plate tectonics and their relationship with earthquakes,a glossary of seismology terms, and much more. There are even a couple of word search puzzles you can play with related to earthquakes and plate tectonics. Highly recommended. Earthquakes in Southern California . Caltech Seismological Laboratory. We love this site. It contains a wealth of information about earthquakes in Southern California. It includes clickable maps of earthquake locations, a clickable map of the fault systems with detailed information on each fault. Be sure to look at some of the animations of earthquakes day by day or year by year. The site also has basic information earthquakes and how to live with them. You'll find information on making you house safe and how to go about preparing for an earthquake. Highly recommended.

74. Memphis Archaeological And Geological Society‚How Do You Measure An Earthquake? How Do You Measure An earthquake? Richter s scale measured the size of earthquakewaves, not an earthquake s total energy, but it was a start. http://www.memphisgeology.org/g_measure.html

The Club The Show Newsletter Archaeology ... Email GEOLOGY ARTICLES Agates Barringer Crater in Arizona Bioturbation Cleaning Quartz ... What Is A Herkimer Diamond? How Do You Measure An Earthquake? 10.25.01Quakes are very hard to measure. The problem is like, say, coming up with one number to indicate the quality of a baseball pitcher. You can start with the pitcher's win-loss record, but the more you study the problem the more things you want to consider, like ERA, defensive range, strikeouts and walks, career longevity, and so on. Baseball statisticians love to tinker with indexes that weigh as many of these factors as possible. Earthquakes are easily as complicated as pitchers. They are fast or slow.

75. EARTH CHANGES Such measurement, Filson said, can be compared to taking the pulse ofthe earth, by monitoring the location and magnitude of earthquakes. http://www.greatdreams.com/earth.htm

updated -6-26-04 EARTH CHANGES EARTHQUAKE PREDICTION http://www.syzygyjob.net/ NASA SATELLITE EARTHQUAKE PREDICTIONS Posted by Jim Berkland on January 13, 1999 Those of you familiar with my Seismic Window Theory will not be surprised by the swarm of quakes near Mt. Hood (max. 3.2M) because there is a Volcanic Window between the standard Seismic Windows. They typical Seismic Window opens the day before the New or Full Moon (whichever is closest to perigee) and runs for eight days (typically to 6 days after syzygy, or S+6). In contrast the volcanic window is typically from day S+7 through day S+14. Five of six major eruptions at Mt. St. Helens in 1980 occurred during a Volcanic Window, the one exception was the big blast of March 18, 1980, moments after the 5.2M quake under the peak. Also the Salton Sea Trough quakes also have their predominant timing during the Volcanic Windows. This morning (day 13) SW of Brawley there was a sequence of quakes with the largest measuring 4.5M. Some 20 years ago an anxious woman called me to tell me that she was petrified about quakes and she wanted to know what could she do to avoid them. I told her that she could maintain two residences and shuttle between the S.F. Bay Area (during Volcanic Windows) and the Salton Sea area (during Seismic Windows). I was not being totally facetious because history bears this out.

76. Earthquakes magnitude or how much energy was released by the fault movement. For eachearthquake there is only one magnitude or Richter measurement. http://www.matter-antimatter.com/earthquakes.htm

Space The Finial Frontier www. Matter AntiMatter .com Home Up Milky Way Galaxy Solar System ... Comets Earthquakes - Under Construction Plate Tectonics , the Cause of Earthquakes. The plates consist of an outer layer of the Earth, the lithosphere, which is cool enough to behave as a more or less rigid shell. Occasionally the hot asthenosphere of the Earth finds a weak place in the lithosphere to rise buoyantly as a plume, or hotspot. The satellite image below shows the volcanic islands of the Galapagos hotspot. Understanding Earthquakes Comparison of Magnitude and Destructive Power Earthquakes are measured in two different ways. The most scientific measure is the Richter scale which tells us an earthquake's magnitude or how much energy was released by the fault movement. For each earthquake there is only one magnitude or Richter measurement. The energies associated with earthquakes of various magnitudes, and of a number of earthquakes and other phenomena. The larger unit of energy for earthquakes is equated to , the yield of TNT. The table was borrowed from GEOLOGY: PRINCIPLES AND APPLICATIONS taught by Dr. J Louie at the University of Nevada at Reno.

77. Idaho Geological Survey This measurement has been named the Richter scale, a numerical gauge ofearthquake energy ranging from 1.0 (very weak) to 9.0 (very strong). http://www.idahogeology.org/Services/GeologicHazards/Earthquakes/eqeducation.htm

Programs and Services Geologic Hazards What are earthquakes? How Earthquakes Cause Destruction Measuring an Earthquake Modified Mercalli Earthquake Intensity Scale How Earthquakes Cause Destruction We live on the thin crust of a layered Earth. The crust or surface of our planet is broken into large, irregularly shaped pieces called plates. The plates tend to pull apart or push together slowly, but with great force. Stresses build along edges of the plates until part of the crust suddenly gives way in a violent movement. This shaking of the crust is called an earthquake. The crust breaks along uneven lines called faults. Geologists locate these faults and determine which are active and inactive. This helps identify where the greatest earthquake potential exists. Most faults mapped by geologists, however, are inactive and have no earthquake potential. When the crust moves abruptly, the sudden release of stored force in the crust sends waves of energy radiating outward from the fault. Internal waves quickly form surface waves, and these surface waves cause the ground to shake. Buildings may sway, tilt, or collapse as the surface waves pass.

78. Black Rapids Roadhouse - Earthquake Article ice. Some of the most precise measurements were taken on glaciers,where the earthquake had clearly offset crevasses. Researchers http://www.blackrapids.org/article2.htm

The Rapids Roadhouse History Older Photos Restoration Project ... Contact Us The Rapids Roadhouse: Articles THEORIES TESTED: Open Alaska countryside easily showed path of shaking By DAN JOLING The Associated Press (Published: January 7, 2004) FAIRBANKS-When a major earthquake ripped through Black Rapids Glacier in central Alaska, most people dove under tables or ran out their doors. Geologist Peter Haeussler headed for a helicopter. The seismographs told Haeussler and other geologists from the U.S. Geological Survey that the largest strike-slip earthquake in North America had just torn through the tundra like a box cutter on carpet. It was a once-in-a-lifetime event for a geologist, but a blanket of snow could have covered up priceless data at any moment. “The phrase that still goes through my head: It really felt like a ticking time bomb,” said Haeussler. “There was so little snow on the ground. We were concerned we were going to lose all information about the fault rupture to a snow storm the next day.” The snow held off. Haeussler and other scientists spent 10 days in the field, carefully measuring and recording the earthquake's effects. They're now hoping that seismic lessons learned in a state with less than one person per square mile can be applied where a similar event could kill thousands.

79. Recent Italy Tremor A Sign Of More To Come 7 on the Richter scale which has happened in California and other earthquakeproneareas residents can then expect about 10 earthquakes measuring 6; 100 http://www.disasterrelief.org/Disasters/971020italy/

Recent Italy Tremor a Sign of More to Come Posted on Mon, 20 Oct 1997 20:07:16 GMT Written by Jessica Gregg McNew, DisasterRelief.org Writer Another earthquake shook Italy's Umbria region on Sunday, causing little new damage in an area plagued by tremors since September 26. There were no injuries reported and no signs of new damage to the Basilica of St. Francis in Assisi, according to news wires. The national treasure was badly damaged in previous recent earthquakes. Residents of Italy may wonder how much longer they have to live in fear of yet another tremor rocking their recovery efforts. A pair of quakes, the highest measuring 5.5 on the Richter scale , left 11 people dead and more than 1,000 homeless on September 26. Another 4.8 tremor left one person dead and many buildings damaged on October 3. Then, another quake hit on October 7. This one measured 5.3. No official measurement of Sunday's quake has been released. Generally, the aftershocks of an earthquake strike for up to a year after the original earthquake, says Jonathan Lees, a professor of geology and geophysics at Yale University. Aftershocks, which are simply the earthquakes that occur after the strongest earthquake in a series of tremors, also occur in a regular pattern. For example, if an area is hit by an earthquake that measures 7 on the Richter scale which has happened in California and other earthquake-prone areas residents can then expect about 10 earthquakes measuring 6; 100 earthquakes measuring 5; and 1,000 earthquakes measuring 4, Lees says.

80. GeoForecaster Earthquake GlobalWatch largest earthquakes in history. The 1960 Chile earthquake measuredMw9.5 and ruptured for over 1000 kilometers. It is believed that http://www1.geoforecaster.com/docs/glossary.asp

Home Subscriber Login Subscription Information Options / Subscribe ... Affiliate Program Further description of some or all of these terms may be found in the FAQs. We also recommend some of our suggested reading list in the Bookstore if you wish to learn more about earthquakes and seismology. Antipode – 180 degrees away (on the exact opposite point of the Earth). If you draw a line from a point on the surface of the Earth through the center of the Earth, it would reappear at the antipode on the opposite side of the Earth. Aftershock – an earthquake or series of earthquakes that occur shortly after the occurrence of a main event. An aftershock series may last for days, months, or years and are usually confined to areas near a fault. Deep earthquakes (such as those that lie several hundred kilometers deep) often do not exhibit aftershocks. This is most likely due to the nature of rocks at these high temperatures and pressures. Background seismicity – see seismicity. Body wave – a compressional seismic wave that travels through the earth. P-waves and S-waves are compressional. Sound waves are also compressional. A good example would be to push a slinky toy in the direction of the length of the slinky you will see areas of compression and extension that move in the direction of the push. These are body waves. Epicenter – location of the source of the earthquake as mapped on the surface of the Earth.

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