81. Lecture I-Introduction Next Slide How do we measure earthquakes? When an earthquake happens it releasesenergy. Next Slide How do we measure earthquakes? Seismometers. Seismograms. http://cronopio.geo.lsa.umich.edu/~crlb/COURSES/107-EQandVolcanoes/Lec5/lecture5

What are Earthquakes? Lecture 5 C. Lithgow-Bertelloni Outline Geographic Distribution Earthquakes in United States Tectonic Setting of North America What is an earthquake? Epicenter Hypocenter Main Shock Aftershock Foreshock Where do earthquakes happen? What is a fault? Types of faults Normal Reverse or Thrust Strike Slip How does an earthquake happen? Causes of Earthquakes Old Ideas New Ideas Elastic Rebound Theory Types of earthquakes Normal- Divergent Reverse or Thrust- Convergent Strike-Slip- Transform Classification by Depth Shallow Intermediate Deep How do we measure earthquakes? Seismometer Seismic Waves P Waves S Waves Surface Waves Location Magnitude Intensity Scale Richter Scale Moment Magnitude Next Slide Geographic Distribution Earthquakes in the United States Mainland LAST 2 WEEKS (check out catalogs of earthquake information in North America here (check out current maps here Next Slide Geographic Distribution Tectonic Setting of North America Next Slide What is an Earthquake? Definition Earthquake : catastrophic release of energy (seconds to minutes) Earthquake : shaking or vibration of the ground Is that enough of a definition?

82. EIS: Educational Outreach Strategy Involves Students In Earthquake Hazard Resear NASA has been making precise geodetic measurements to assess earthquake hazardassociated with the subduction zone process in Alaska since 1984. http://www.agu.org/sci_soc/articles/sauber.html

Home Science and Society Science for Everyone Solid Earth GEODESY AND SEISMOLOGY Educational Outreach Strategy Involves Students in Earthquake Hazard Research by J. Sauber, S. Stockman, and T. Clark, Laboratory for Terrestrial Physics, NASA's Goddard Space Flight Center, Greenbelt, Maryland NASA has been making precise geodetic measurements to assess earthquake hazard associated with the subduction zone process in Alaska since 1984. In 1995, a new strategy for making geodetic measurements was implemented that included local residents in the measurement program, and in 1997, the program was expanded to include teachers and students at five high schools. For the inhabitants of Alaska, understanding the hazards and underlying physical processes associated with earthquakes has immediate personal relevance. Large earthquakes occur yearly, great earthquakes have occurred during the lifetime of many residents, and the weekly testing of the tsunami warning system in coastal towns is a reminder of the devastation caused by earlier tsunamis generated near Alaska and serve as a cautionary note about future inundation. Fig. 1. Location of geodetic sites (open diamonds) occupied in 1993, 1995, and/or 1997, and the permanent GPS site near Fairbanks (open square). The five boxes with the high school name on the right side indicate the observation region of each school. The shaded regions (with year) indicate the rupture zones of major earthquakes in southern Alaska during this century. The predicted rate of motion of the Pacific plate relative to a fixed North American plate is given by the vector in the lower right-hand corner.

83. AGU: Mexican Earthquake Generates Tsunami At the Vida del Mar resort, maintenance workers felt the earthquake and noticedthe This locale was the point of highest measured runup (10.9 m), probably http://www.agu.org/sci_soc/eisborerro.html

OCEAN SCIENCES Mexican Earthquake Generates Tsunami, New Data, and Unusual Photos Permission is hereby granted to journalists to use this material so long as credit is given, and to teachers to use this material in classrooms. Faced with the onrushing water of a tsunami wave, Jose "Pepe" Martinez of La Manzanilla, Mexico, stood his ground and captured the event on film. Personal accounts, photos, and data recorded by newly installed offshore sensors are testimony to how vulnerable flat lands near river inlets are to tsunami attacks and show that even moderate tsunamis can produce large currents inside harbors. by Jose Borerro, University of Southern California, Los Angeles; Modesto Ortiz, CICESE, Oceanology Division, San Diego;Vasily Titov and Costas Synolakis, University of California, Los Angleles On October 9, 1995, an earthquake of M w = 8.0 shook the Pacific coast of central Mexico. Centered offshore of the states of Jalisco and Colima, the earthquake caused extensive damage near Manzanillo and was felt strongly in Mexico City. Approximately 40 people were killed and about 100 injured, and many tall buildings were destroyed or severely damaged. The earthquake set off a moderate tsunami that affected approximately 200 kilometers of coastline and sent tsunami run-up Measuring the Tsunami and its Damage Although the Manzanillo tsunami did not produce extreme 30-m runup heights observed in Flores, Indonesia, in 1992 or in Okushiri, Japan, in 1993, it was an interesting event for several reasons. Eyewitnesses observed the tsunami and were able to describe the sequence of motions of the sea's surface well. By serendipity, a week before the tsunami, two moorings of bottom-mounted pressure sensors had just been installed offshore of La Manzanilla for a study of internal wave motions. This array of sensors recorded a

84. Nasa: New Technology To Help Measurement And Study Of Earthquakes New Technology to Help measurement and Study of Earthquakes. RELEASE96218. NEW TECHNOLOGY TO HELP measurement AND STUDY OF EARTHQUAKES. http://www.qadas.com/qadas/nasa/nasa-hm/0660.html

New Technology to Help Measurement and Study of Earthquakes NASA HQ Public Affairs Office ( NASANews@luna.osf.hq.nasa.gov Mon, 28 Oct 1996 14:17:42 -0500 Messages sorted by: [ date ] [ thread ] [ subject ] [ author ] Next message: NASA HQ Public Affairs Office: "NASA Managers Defer Setting STS-80 Launch Date Pending Resolution of Rocket Motor Nozzle Issue" Previous message: NASA HQ Public Affairs Office: "1996 Antarctic Ozone Hole Below Record Average Size" Douglas Isbell Headquarters, Washington, DC October 28, 1996 (Phone: 202/358-1753) Mary Hardin Jet Propulsion Laboratory, Pasadena, CA (Phone: 818/354-5011) Cheryl Dybas National Science Foundation, Arlington, VA (Phone: 703/306-1070) Don Kelly U.S. Geological Survey, Reston, VA (Phone: 703/648-4466) RELEASE: 96-218 NEW TECHNOLOGY TO HELP MEASUREMENT AND STUDY OF EARTHQUAKES 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

85. Borehole Tensor Strain Measurements In California more detail of results include Wyatt FK, Agnew DH and Gladwin MT(1994) ContinuousMeasurements of Crustal Deformation for the 1992 Landers earthquake Sequence http://www.em.csiro.au/airborne_gravity/research/projects/surveystrain/tensorcal

Borehole Tensor Strain Measurements in California High precision and high stability measurements of the horizontal strain field in a region are made in California using a Borehole Tensor Strain Measurement instrument (BTSM). These instruments are installed at a depth of 100-200 metres at 7 sites in California. The sites are shown in red in the accompanying map CHT and GAT are situated in the East Bay region of San Francisco Bay. SJT is close to San Juan Bautista to the south of San Francisco EDT, FLT and DLT are situated in the Parkfield region of central California PFT instrument is in southern California , in the mountains near Palm Desert. CLT is situated in the Los Angeles region in 1996 you will need Acrobat reader to view the PDF above. Click he a re to download These instruments provide strain data on Long term strain accumulation. Data records are available from SJT and PFT from 1984, and from the three Parkfield sites EDT FLT and DLT from 1987, and from the East Bay sites

86. Physics Today June 2001 Although the measurement errors are still large, figure 4 indicates that the ratiofor large earthquakes (M 5) is 10100 times larger than that for small http://www.physicstoday.com/pt/vol-54/iss-6/p34.html

Back to Table of Contents June Articles: The Physics of Earthquakes Flexible Methods for Microfluidics The Early Days of Pugwash References Site Index Physics Today Home Page Current Issue Past Contents Job Ads Upcoming Meetings Buyer's Guide About Physics Today Contact Us Advertising Information Print Ad Rates and Specs Online Ad Rates and Specs Advertiser Index Product Information Information Exchange The Physics of Earthquakes Hiroo Kanamori and Emily E. Brodsky Seismologists have never directly observed rupture in Earth's interior. Instead, they glean information from seismic waves, geodetic measurements, and numerical experiments. The recent earthquakes in Taiwan, Turkey, and India tragically demonstrate the abruptness with which earthquakes occur and the devastation that often accompanies them. Scientists, emergency officials, and the public are greatly interested in earthquakessudden fractures in Earth's crust followed by ground shakingand have many questions about them. For example, When do earthquakes occur? More precisely, what long-term processes and short-term triggers produce earthquakes? Although plate tectonics has provided a successful framework for understanding the long-term processes, the short-term triggers remain obscure, making earthquakes unpredictable. An equally important question and a fundamental challenge to the science of geophysics is, What happens during an earthquake? That is, What are the forces and motions during a seismic event? The answer to this question has practical consequences for mitigating the effects of the expected ground motion.

87. Earthquakes Magnitude is a measure of energy released in an earthquake by measuringthe amplitude of ground motion with a seismograph. This http://www.gsa.state.al.us/gsa/EQ2/eq.html

EARTHQUAKES IN ALABAMA Charleston, South Carolina, earthquake of 1886 Source: U.S. Geological Survey EARTHQUAKE HAZARDS EARTHQUAKE SIZE EARTHQUAKE MYTHS EARTHQUAKES AND ALABAMA ... HISTORIC ALABAMA EARTHQUAKES EARTHQUAKE HAZARDS National maps of earthquake shaking hazards provide information essential to creating and updating the seismic design provisions of building codes used in the United States. The 1996 U.S. Geological Survey shaking-hazard map for the United States is based on current information about the rate at which earthquakes occur in different areas and on how far strong shaking extends from quake sources. Colors show the levels of horizontal shaking that have a 1-in-10 chance of being exceeded in a 50-year period. Shaking is expressed as a percentage of g (g is the gravitational acceleration of a falling object). Although strong earthquakes occur less frequently in the eastern United States, damage in this area could be catastrophic in a powerful quake because buildings and other structures have not been designed to withstand severe earth shaking. Damage to buildings, dams, highways, power lines, and similar structures only partly depend on the amount of energy released during an earthquake. Certain kinds of earth materials enhance the effects of earthquake vibrations. In Alabama, structures built on thick, loose sediments of river floodplains and filled areas are more likely to be damaged than structures built on bedrock. In fact, seismic intensity may increase as much as one full unit on the Modified Mercalli Intensity Scale if loose sediments are present. Also, loose sediments with a high moisture content can turn to liquid when shaken.

88. What Is Richter Magnitude? What is Richter Magnitude? This website contains class notes from part of a Geology 101 (physical geology) course. It describes the Richter scale, and how it measures the magnitude of an http://rdre1.inktomi.com/click?u=http://www.seismo.unr.edu/ftp/pub/louie/class/1

89. Richter Magnitude for earthquakes in southern California, seismologists have developed scale factorsto extend Richter s magnitude scale to many other types of measurements on http://www.seismo.unr.edu/ftp/pub/louie/class/100/magnitude.html

What is Richter Magnitude? Short answer: Seismologists use a Magnitude scale to express the seismic energy released by each earthquake. Here are the typical effects of earthquakes in various magnitude ranges: Earthquake Severity Richter Earthquake Magnitudes Effects Less than 3.5 Generally not felt, but recorded. 3.5-5.4 Often felt, but rarely causes damage. Under 6.0 At most slight damage to well-designed buildings. Can cause major damage to poorly constructed buildings over small regions. 6.1-6.9 Can be destructive in areas up to about 100 kilometers across where people live. 7.0-7.9 Major earthquake. Can cause serious damage over larger areas. 8 or greater Great earthquake. Can cause serious damage in areas several hundred kilometers across. Although each earthquake has a unique Magnitude , its effects will vary greatly according to distance, ground conditions, construction standards, and other factors. Seismologists use a different Mercalli Intensity Scale to express the variable effects of an earthquake.

90. Tech Topics: Earthquakes: Measuring Earthquakes You ll find some interesting pictures, photos, and descriptions of seismographs,which have measured earthquakes over time. A seismograph http://www.thetech.org/exhibits/online/topics/32a.html

Humans have lived with earthquakes for a long time, and many cultures have developed ways to measure them. Devices that measure the strength (or magnitude), length, location (or epicenter), and direction of earthquakes are called seismographs. You will see how seismographs work, and how they have become more and more accurate over time. You'll find some interesting pictures, photos, and descriptions of seismographs, which have measured earthquakes over time. A seismograph takes the motion of an earthquake and turns it into a seismogram, or a graph of the earth's movement. Quick Menu: Earthquakes Measurement Seismographs Epicenter ... Activity 1

91. Delhi Dairy It starts from 1 and has no upper limit and operates on a power of 10 eg an earthquakemeasuring 2 on this scale releases 10 times energy than that measuring 1 http://www.worldnewsservices.com/Delhi Dairy.htm

92. Geodynamics: Cascadia Subduction Zone In the interseismic period between mega-earthquakes the rocks are being The firstmethod involves continuous daily measurements of position using a permanent http://www.pgc.nrcan.gc.ca/geodyn/cascadia.htm

Earthquake Processes: Cascadia Subduction Zone Measurement of Subduction Zone Deformation Subduction-thrust earthquakes or mega-earthquakes are known to be one stage of a subduction-thrust Earthquake Cycle The techniques mentioned above are high-precision geodetic techniques which have been developed to the required accuracy only recently. Another method called Very Long Baseline Interferometry (VLBI) uses the most fundamental reference system available, extragalactic quasars. A version of this system is being developed in Canada in a co-operative venture involving a number of Canadian scientific agencies: Geodetic Survey of Canada, Institute for Space and Terrestrial Science (ISTS), National Research Council (NRC) and Geological Survey of Canada. A number of other ways of measuring crustal deformation are 1) repeated resurveying of old geodetic survey networks, 2) repeated resurveying of old levelling lines, 3) repeated resurveying of gravity networks, and 4) measurement of changes in mean sea level (MSL). All of the high-precision methods used in the study of crustal deformation are being carried out in co-operation with the Geodetic Survey of Canada, while MSL studies are enabled through the cooperation of the Canadian Hydrographic Survey. Using the Global Positioning System (GPS) satellites, and a network of permanent GPS receivers, the relative motion of points on the earth's surface can be monitored at the level of a few millimetres per year. The arrows in this diagram show the measured annual rates and directions of motion of specific sites of the

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