21. Page 3 -- Measuring Earthquakes Ground Motion The Shaky Foundation of earthquake measurements. Groundmotion, including (but not limited to) the shaking that we http://www.data.scec.org/Module/sec3pg03.html

Ground Motion: The Shaky Foundation of Earthquake Measurements Ground motion, including (but not limited to) the shaking that we associate with earthquakes, is the basis for almost every type of modern measurement associated with earthquakes. Even those types of earthquake monitoring that do not directly measure ground motion measure effects related to movement in the Earth's crust disturbances in electromagnetic fields, changes in water levels, and so on. This dependency upon ground motion only makes sense; earthquakes are essentially defined as the sudden movement of one part of the Earth's brittle crust past another. They are also the direct result of the grandest kind of motion on the planet: the slow but continuous movement of Earth's tectonic plates. The science of seismology was founded upon the observation of ground motion. Well before instrumental recording of earthquakes began, people learned to classify earthquakes by the strength of the shaking involved. This was, after all, the element of any earthquake that mattered most to anyone living in the vicinity. Would living quarters still be standing? Would public works like aqueducts need repair or rebuilding? Or was the shaking simply enough to startle residents, but cause no damage? Though the first efforts to describe the relative severity of earthquake effects were very informal, gradually the language was refined. The drive toward labelling and categorization of the natural world that swept other fields of knowledge (e.g. botany, astronomy, etc.) after the European Renaissance was eventually applied to earthquakes. This led to the concept of earthquake

22. 174-Assessment Of Seafloor Earthquake Ground Motions , The objective was to analyze existing and future recordings from theSeafloor earthquake measurement System (SEMS), and to perform theoretical...... http://www.mms.gov/tarprojects/174.htm

Project Number Date of Summary March 31, 1995 Subject Assessment of Seafloor Earthquake Ground Motions Performing Activity U.S. Geological Survey, Menlo Park Principal Investigator Dr. David M. Boore Contracting Agency Minerals Management Service Estimated Completion Complete Description The objective was to analyze existing and future recordings from the Seafloor Earthquake Measurement System (SEMS), and to perform theoretical calculations to improve our understanding of seafloor motions from earthquakes. The study will determine if the ground motions of the ocean bottom are fundamentally different than those recorded offshore from similar earthquakes. In addition, the investigator will use systems identification and adaptive filter techniques on the SEMS recordings and recordings from nearby platforms to identify the dynamic characteristics of the soil and the structure. Progress SEMS data from the Santa Barbara Island earthquake (September 4, 1981), the North Palm Springs earthquake (July 8, 1986), the Oceanside earthquake (September 13, 1986) and the Upland earthquake (February 28, 1990) was sent by Sandia to the U.S. Geological Survey for further analysis. The data needs to be put into a consistent format and certain `front-end` processing is required to obtain an accurate probe orientation and record start time measurements. International Oil Spill Research Projects by Category Projects by Number ... Oil Valuation Last Updated:

23. Lecture-template earthquake measurement USGS Plate Tectonics Site; The San Andreas Fault;Earthquakes causes, distribution, measurements, and prediction; http://www.salemstate.edu/~lhanson/gls100/gls100_earthqks.html

Assignments: Text: Essentials of Geology Read Chapters 15 Earthquake exercise (Not Assigned this semester) Online Lab: Virtual Earthquake Complete and turn in certificate Introductory concepts: Rocks deform when stressed (when force is applied) Deformation= Strain (change in shape or volume) Ways in which materials deform elastic (recoverable): no direct evidence plastic (flow): produces folds in rocks brittle (rupture): produces joints and faults Factors governing deformation Heat Pressure Rate at which stress is applied Strength of material Generation of earthquakes Earthquakes occur along faults : major breaks in the crust along which movement occurs and where stress tends to accumulate Elastic rebound theory : Accumulated strain energy is suddenly released upon rupture Energy travels as seismic waves Body waves: These energy waves radiate from the epicenter through the body of the earth ( animation from the PBS Savage Earth Earthquake site) S-wave (shear, secondary): travels only through solids

24. 19 Lets Get Visual2 Magnitudes of earthquakes can be measured and compared. Activity Overview modifiedMercalli. Procedure 1. Discuss various scales of earthquake measurement. http://www.seetc.org/teachers/lessonplans/platetec/html/19_lets_get_visual2.html

25. Troubled Times: Earth Waves The first thing I have to explain to you is the earthquake measurement problems.The most common measurement scale is the Richter Magnitude scale. http://www.zetatalk.com/shelter/tshlt08e.htm

Earth Waves I recently e-mailed a number of geologists and asked their opinion of how an underground structure would fare in a severe earthquake and here's the response I got. Here's what I wrote: To whom it may concern: I am doing a research project and was wondering if you could help me. How do you feel an underground structure would fare against a major earthquake? By major I mean at least 9 on the Richter scale. This underground structure would be made of reinforced materials, and be constructed in a dome or geodesic dome shape, because of it's amazing strength. Do you feel such a structure would fare better or worse than an above-ground structure? Also, if you do feel it could survive a 9 point earthquake, do you think it could also survive a 15 point quake? Thank you for your help. Here's the response I got: Hi there. Interesting question. The first thing I have to explain to you is the earthquake measurement problems. The most common measurement scale is the Richter Magnitude scale. On the Richter scale, quakes of 2.0 or less are usually not felt by people. The largest quakes in the world have had magnitudes of 8.8 to 8.9. Although there is no limit to the upper end of the Richter scale, the theoretical limit is about 9.5 simply based on the fact that rocks experiencing enough pressure to break that violently will actually bend or melt before they break. The Seismic Moment measurement is becoming the more often used (and more accurate) form of measurement. The largest known quake on this scale measured at 9.6. There is no scale or measuring method which could result in a "15 point quake" as you suggest.

26. BSSA, Volume 89:1 Analysis of Earthquake Recordings Obtained from the Seafloor earthquake measurementSystem (SEMS) Instruments Deployed off the Coast of Southern California http://www.seismosoc.org/publications/BSSA_html/bssa_89-1/ssa_toc_89-1.htm

Bulletin of the Seismological Society of America Volume 89 - Number 1 - February 1999 Contents Deaggregation of Probabilistic Ground Motions in the Central and Eastern United States Stephen Harmsen, David Perkins, and Arthur Frankel Seismic Coupling of Interface Modes in Sedimentary Basins: A Recipe for Disaster Spatial Distribution of High-Frequency Energy Radiation on the Fault of the 1995 Hyogo-Ken Nanbu, Japan, Earthquake ( M w ... 6.9) on the Basis of the Seismogram Envelope Inversion Hisashi Nakahara, Haruo Sato, Masakazu Ohtake, and Takeshi Nishimura A Semi-empirical Method for Simulating Strong Ground Motions Based on Variable-Slip Rupture Models for Large Earthquakes Kazuo Dan and Toshiaki Sato 3D Elastic Finite-Difference Modeling of Seismic Motion Using Staggered Grids with Nonuniform Spacing Arben Pitarka 3D Displacement Finite Differences and a Combined Memory Optimization Beginning of Earthquakes Modeled with the Griffith's Fracture Criterion Tamao Sato and Hiroo Kanamori Defining Seismogenic Sources from Historical Earthquake Felt Reports Paolo Gasperini, Filippo Bernardini, Gianluca Valensise, and Enzo Boschi An Alternative Method for a Reliable Estimation of Seismicity with an Application in Greece and the Surrounding Area C. Papazachos

27. Newspaper Articles For 1975 Yellowstone National Park Earthquake were recorded at 105 pm and 122 pm An earthquake measurement device at the Universityof Utah measured the intensity at 5.5 to 6 on the Richter Scale. http://www.seis.utah.edu/NEHRP_HTM/1975yell/n1975ye1.htm

QUAKE JOLTS YELLOWSTONE WEST YELLOWSTONE, Mont. (AP) Yellowstone National Park absorbed without damage or harm to humans on Monday the most severe earthquake since a killer quake of 1959. The 1959 earthquake killed 19 persons and dammed the Madison River into a new body of water now called Quake Lake. The 1959 tragedy measured 7.1 on the Richter Scale while the National Earthquake Information Center of Golden, Colo., put the strength of Monday's quake at 6.0. The focal points of earth movement, called epicenters, of the two earthquakes were in the same general area, a portion of southern Montana just to the northwest of Yellowstone's border. Acting Yellowstone Supt. Robert Haraden said crews worked Monday night to clear one park road that was closed when the earthquake shook down boulders in the fragile beauty of the country between Norris and Madison Junction. Haraden said all Yellowstone campgrounds and facilities remained open. Earth movement is constant at Yellowstone. Haraden noted that a small seismograph stationed at the visitor center near the Old Faithful geyser has recorded more than 2,000 earth movements so far this year. Most are so tiny that humans cannot feel them but Monday's earthquake rumbled with a force that shook buildings and rattled windows 200 miles away. Citizens in Great Falls and Billings reported feeling the earthquake.

28. California Earthquake-Measurement Field Sites California earthquakemeasurement Field Sites. This map of California shows the Stanford field sites as solid of the M7.1 Loma Prieta earthquake that occurred in October 1989 http://www-star.stanford.edu/~acfs/Field_sitesMap.html

California Earthquake-Measurement Field Sites [Return to research page , or home page

29. Earthquake Glossary Earth. teleseismic. Pertaining to earthquakes at distances greaterthan 1,000 km from the measurement site. tensional stress. The http://earthquake.usgs.gov/4kids/eqterms.html

Latest Quakes For Kids Only Regional Websites HOME ... SEARCH For Kids Only Earthquake Glossary See also the Earthquake Image Glossary and A B C D ... I J K L M N ... T U V W X Y Z acceleration. When you step on the accelerator in the car or put on the brakes, the car goes faster or slower. When it is changing from one speed to another, it is accelerating (faster) or decelerating (slower). This change from one speed, or velocity, to another is called acceleration. During an earthquake when the ground is shaking, it also experiences acceleration. The peak acceleration is the largest acceleration recorded by a particular station during an earthquake. accelerogram. The recording of the acceleration of the ground during an earthquake. accelerograph. An instrument that records the acceleration of the ground during an earthquake, also commonly called an accelerometer.

30. FEMA FOR KIDS: EARTHQUAKES he intensity of an earthquake can be measured. One measurement iscalled the Richter scale. earthquakes below 4.0 on the Richter http://www.fema.gov/kids/quake.htm

Shake With The Quake Story Rumble Tumble Story ... Earthquake Legends arthquakes are the shaking, rolling or sudden shock of the earth’s surface. Earthquakes happen along "fault lines" in the earth’s crust. Earthquakes can be felt over large areas although they usually last less than one minute. Earthquakes cannot be predicted although scientists are working on it! Most of the time, you will notice an earthquake by the gentle shaking of the ground. You may notice hanging plants swaying or objects wobbling on shelves. Sometimes you may hear a low rumbling noise or feel a sharp jolt. A survivor of the 1906 earthquake in San Francisco said the sensation was like riding a bicycle down a long flight of stairs. he intensity of an earthquake can be measured. One measurement is called the Richter scale. Earthquakes below 4.0 on the Richter scale usually do not cause damage, and earthquakes below 2.0 usually can’t be felt. Earthquakes over 5.0 on the scale can cause damage. A magnitude 6.0 earthquake is considered strong and a magnitude 7.0 is a major earthquake. The Northridge Earthquake, which hit Southern California in 1994, was magnitude 6.7. Earthquakes are sometimes called temblors, quakes, shakers or seismic activity. The most important thing to remember during an earthquake is to DROP, COVER and HOLD ON. So remember to DROP to the floor and get under something for COVER and HOLD ON during the shaking.

31. Maine Geology - Earthquakes The largest accurate measurement was on June 15, 1973 from an earthquake juston the Quebec side of the border from northern Oxford County, Maine, with a http://www.state.me.us/doc/nrimc/pubedinf/factsht/bedrock/quake.htm

State Agencies Web Policies My Maine.gov Email this page MAINE DEPARTMENT OF CONSERVATION Maine Geological Survey Earthquakes in Maine Henry N. Berry IV Maine Geological Survey Department of Conservation Seismic Activity Seismic activity in Maine is typical of the Appalachian region of northeastern North America. There is a low but steady rate of earthquake occurrence. The earthquakes are presumably caused by modern stress being released occasionally along zones of weakness in the earth's crust, but a more specific cause for the earthquake activity is not known. Recorded earthquake locations and detailed seismic motion studies do not show any clear correlation with either local or regional geologic features (Ebel, 1989). No significant amount of motion has been shown for any fault since the last Ice Age, about 20,000 years ago, and geologic evidence demonstrates that many faults have been inactive since the formation of the Appalachians, over 300,000,000 years ago. None of the ancient faults in Maine have been identified as active (Anderson et al., 1989; Osberg et al., 1989). The largest earthquake recorded in Maine between 1747 and 1992 was near Eastport in 1904 with a Modified Mercalli intensity estimated at VII. The largest accurate measurement was on June 15, 1973 from an earthquake just on the Quebec side of the border from northern Oxford County, Maine, with a Richter magnitude of 4.8 (Johnston, 1995). Most Maine earthquakes are of small magnitude. Many are too small to feel. No Maine earthquake has caused significant damage. The persistent activity, however, indicates that some crustal deformation is occurring and that a larger earthquake cannot be ruled out (Ebel, 1989). Based on past earthquake data collected over a limited time span (1975-1982) from the whole of New England, and assuming that Maine is a representative part thereof, Ebel (1984) has estimated the return times for earthquakes in Maine as follows:

32. Aftenposten Norway, Norwegian News In English earthquake measurement was Rocknes impact. Instruments at theGeophysical Institute at Bergen University reveal three powerful http://www.aftenposten.no/english/local/article714926.ece

First published: 22 Jan 2004, 14:54 AFTENPOSTEN English frontpage Norwegian frontpage NEWS ... Press release FEATURES Only in Norway The Royals Webcams in Norway Readers respond ... WEBCAMS See Norway live. See our webcams Most visited Oslo: Karl Johan Oslo: Herbern Aker Brygge Oslo: Aker Brygge Oslo: Utsikt fra Postgirobygget ... SEARCH News in english: How to search INFO About the newsdesk Contact us Advertising info Rate calculator ... Streetmap 'Earthquake' measurement was "Rocknes" impact Instruments at the Geophysical Institute at Bergen University reveal three powerful measurements in the area where the Rocknes capsized, just before the ship overturned. Experts can see no other explanation for the readings other than the ship striking bottom, newspaper Bergens Tidende reports. Related stories: Unstable "Rocknes" floats higher Bondevik promises aid after accident Survivors say doomed ship ran aground Three dead, 15 missing in ship disaster ... Bulker survivors doing well, hopes dwindle more will be found "The readings are consistent with the boat scraping along the mountain edge first. Afterwards we have the first, powerful impacts," Institute professor Jens Havskov told the newspaper. The readings at four measuring stations in the area show a minor impact followed by a larger one. Finally a powerful blow is registered, and two minutes later the first emergency messages came from the Rocknes.

33. Locating And Measuring Earthquakes - Putting Down Roots In Earthquake Country Locating and measuring earthquakes. Where Seismologists have developed anew measurement of earthquake size, called moment magnitude. Moment http://www.earthquakecountry.info/roots/measuring.html

@import url("roots.css"); Faults Shaking Many people believe that earthquakes are more common in certain kinds of weather. In fact, no correlation with weather has been found. Earthquakes begin many kilometers (miles) below the region affected by surface weather. People tend to notice earthquakes that fit the pattern and forget the ones that don't. Also, every region of the world has a story about earthquake weather, but the type of weather is whatever they had for their most memorable earthquake. Locating and measuring earthquakes Where and when was the earthquake? Earthquakes are recorded by a seismic network. Each seismic station in the network measures the movement of the ground at that site. In an earthquake, the slip of a block of rock over another releases energy that makes the ground vibrate. That vibration pushes the adjoining piece of ground, causing it to vibrate, and thus the energy travels out from the earthquake in a wave. As the wave passes by a seismic station, that piece of ground vibrates and this vibration is recorded. Knowing how fast seismic waves travel through the earth, seismologists can calculate what time and what location of the earthquake would give the pattern of shaking that was recorded at several stations. This process used to take almost an hour when done manually.

34. InforMARE - Press Review May 13, 2004, The online newspaper devoted to the world of transports, 154957GMT+1. January 22, 2004, earthquake measurement was Rocknes impact. http://www.informare.it/news/review/2004/aftenposten0046.asp

June 09, 2004 The on-line newspaper devoted to the world of transports 00:32:18 GMT+1 January 22, 2004 'Earthquake' measurement was "Rocknes" impact Instruments at the Geophysical Institute at Bergen University reveal three powerful measurements in the area where the Rocknes capsized, just before the ship overturned. Experts can see no other explanation for the readings other than the ship striking bottom, newspaper Bergens Tidende reports. "The readings are consistent with the boat scraping along the mountain edge first. Afterwards we have the first, powerful impacts," Institute professor Jens Havskov told the newspaper Read more on Aftenposten Interaktiv Search on Select the subject: All News Ports Tourism Database Aviation Trucking Index Home Page Press Review - via al Ponte Reale 1/41 - 16124 Genoa - ITALY phone: +39.10.2462122, fax: +39.10.2462181, e-mail: admin@informare.it

35. Calculating Depths Of Deep Earthquakes To find out where your measurement should be plotted on the figure, first find the horizontallines you drew meet, gives you an estimate of the earthquake depth http://lasker.princeton.edu/ScienceProjects/curr/deepeq/deepeq.htm

Calculating Depths of Deep Earthquakes The depth to very deep earthquakes is usually established by measuring the difference in arrival time of the P and pP wave. This is something you can do yourself with a bit of practice. You may be able to discover the deepest earthquake known so far! The best estimate for the deepest known earthquake is 684 km deep, under the Fiji Islands in the Southwest Pacific, on June 17, 1977. How do you go about this? First learn to recognize the pP wave. It has very much the same shape as the P wave (it reflects from the Earth's surface, very much like a reflection in a mirror, before going on its journey to the seismic station). Hint: sometimes it is much easier to see the pP and P similarity when you transform the seismogram to displacement rather than velocity. This is because pP spends more time in the "syrupy" upper mantle above the earthquake, where it looses some of the high frequencies (little wiggles). We provide some selected pairs of P and pP waves from the Global Seismograph Network in the file deepP.dat

36. Measurement measurement. earthquakes can be measured in several ways. The The secondtype of measurement is the magnitude of the earthquake. Magnitude http://scign.jpl.nasa.gov/learn/eq8.htm

Measurement Earthquakes can be measured in several ways. The first way is to describe the earthquake's intensity. Intensity is the measure, in terms of degrees, of damage to the surface and the effects on humans. Intensity records only observations of effects on the crust, not actual ground motion or wave amplitudes which can be recorded by instruments. While intensity helps to determine how large of an area was effected, it is not an accurate measure of the earthquake for many reasons. Two such reasons are: only the effect on an area showing the greatest intensity is reported, which can imply a greater or lesser intensity than what actually occurred, and the way in which seismic waves travel varies as they pass through different types of rocks, so some areas near by may feel nothing because they are built on faulted rock, while other areas quite a distance from the foci will feel the effects because they are built on compact homogenous rocks. The second type of measurement is the magnitude of the earthquake. Magnitude does not depend on population and effects to ground structures, but rather on wave amplitude and distance. Magnitude is determined using mathematical formulae and information from seismograms. One such magnitude scale is the Richter scale. This magnitude scale is logarithmic, meaning each step in magnitude is exponentially greater than the last.

37. Concepts Covered measurement. Energy released in an earthquake can be measured in severalways. Intensity, magnitude Using GPS to measure earthquakes. GPS (and http://scign.jpl.nasa.gov/learn/oview3.htm

The Southern California Integrated GPS Network Education Module Exploring the use of space technology in earthquake studies Concepts covered Master list for Sections 1-4 Plate tectonics Structure of the Earth Geophysical studies have uncovered much new information about the Earth's interior, including its composition and mechanical properties. History of plate tectonics Plate tectonic theory had its roots in Alfred Wegener's erroneous "continental drift" theory (1915) but since the 1950's, geologic and geophysical evidence has helped it gain widespread acceptance as a model of Earth processes. Plates Plate tectonic theory tries to account for the movement of plates over time. According to this model, the lithosphere is divided into 7 major and several minor plates which move in relation to one another. Plate boundaries Plate boundaries are wide zones of deformation where two or more plates interact. They are found at the edge of plates and are characterized by three distinct motions. Forces Forces create stress, which acts to change the volume and/or shape of a material. There are three different stresses which act upon a material in three distinct ways.

38. Electronic Desktop Project - Virtual Earthquake You are to locate the epicenter of an earthquake by making simple measurement onthree seismograms that will be sent to you by the Virtual earthquake program. http://vcourseware.calstatela.edu/VirtualEarthquake/

Welcome to Virtual Earthquake Virtual Earthquake is an interactive Web-based activity designed to introduce you to the concepts of how an earthquake EPICENTER is located and how the RICHTER MAGNITUDE of an earthquake is determined. The Virtual Earthquake program is running on a Web Server at California State University at Los Angeles. You can interact with Virtual Earthquake NEW : A completely revised version of Virtual Earthquake can be found HERE . This new applet-based version is more inquiry-based than the original version and contains tools so instructors can assess student learning. Currently it runs only under IE on PCs. (After you complete Virtual Earthquake, check out the Geology Labs On-Line home page for the latest information about project activities. Activities about age dating, river discharge and river flooding are available.) Instructors: here is some important information Virtual Earthquake will show you the recordings of an earthquake's seismic waves detected by instruments far away from the earthquake. The instrument recording the seismic waves is called a

39. Virtual Earthquake - An Introduction The actual location of the earthquake s epicenter will be on the perimeter of a OneS P measurement will produce one epicentral distance the direction from http://vcourseware.calstatela.edu/VirtualEarthquake/VQuakeExecute.html

What's an earthquake? Earthquakes occur because of a sudden release of stored energy. This energy has built up over long periods of time as a result of tectonic forces within the earth. Most earthquakes take place along faults in the upper 25 miles of the earth's surface when one side rapidly moves relative to the other side of the fault. This sudden motion causes shock waves (seismic waves) to radiate from their point of origin called the focus and travel through the earth. It is these seismic waves that can produce ground motion which people call an earthquake. Each year there are thousands of earthquakes that can be felt by people and over one million that are strong enough to be recorded by instruments. Strong seismic waves can cause great local damage and they can travel large distances. But even weaker seismic waves can travel far and can be detected by sensitive scientific instruments called seismographs What are earthquake (Seismic) Waves?

40. Earthquakes Terms to Know MAGNITUDE – The relative strength of an earthquake. TheRichter magnitude is the most common expression of this measurement. http://www.99main.com/~leoc/earthqua.htm

New England Earthquake Safety Tips The actual movement of the earth is seldom the direct cause of death or injury. Most casualties occur from falling objects and debris because the shocks can shake, damage, or demolish buildings. Earthquakes may also trigger landslides, cause fires, and generate huge ocean waves called tsunamis. Connecticut has the oldest record of earthquakes in the United States. The earliest settlers learned of seismic activity in this area, dating back to 1568 in Moodus, from the native Indians. Earthquakes measuring more than 4.3 on the Richter scale have shaken our largest cities. Connecticut is considered to be a in a moderate seismic risk zone as defined by the Federal Emergency Management Agency. The hard base rock in Connecticut can transmit seismic waves over an area 4 to 40 times more efficiently than a similar earthquake in California. People in our region can be at greater risk since many buildings are not built with reinforced materials nor seismically designed. The chance of a damaging earthquake of magnitude 5.0 or greater is 1 in 20 each year. The odds of a magnitude 6.0 earthquake in Connecticut are about 1 in 300 annually.

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