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Earthquakes. Source: USGS. Source: NPS. Seismic Hazard. Source: USGS. California Tectonics: Present. Source: USGS. California Tectonics: Past. http:// www.nps.gov/prsf/naturescience/images/Subduction-animation_1.gif. What Is An Earthquake?.

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Earthquakes
Earthquakes

Source: USGS

Source: NPS


Seismic hazard
Seismic Hazard

Source: USGS


California tectonics present
California Tectonics: Present

Source: USGS



http://www.nps.gov/prsf/naturescience/images/Subduction-animation_1.gif


What Is An Earthquake?

_______________________________________________

_______________________________________________

_______________________________________________

_______________________________________________

_______________________________________________

http://geography.sierra.cc.ca.us/booth/California/1_lithosphere/earthquakes.htm


Types of earthquake waves
Types of Earthquake Waves

  • Surface waves

    • Complex motion

    • _________________________________

  • Body waves

  • 1. Primary (P) waves

    • Push-pull (__________________) motion

    • Travel through solids, liquids, and gases

    • ___________________of all earthquake waves

  • 2. Secondary (S) waves

    • "Shake" motion

    • Travel only through _____________

    • ____________________ than P waves



  • A seismogram records vs
    A seismogram records ________________vs. _________

    http://ww2.lafayette.edu/~malincol/Geol120/seismogram.GIF


    Locating an from 3 seismograph stations

    Measure the difference in arrival of ____________ waves.

    Locating an ____________ from 3 seismograph stations


    Step 2 of locating the epicenter
    Step 2 of locating the epicenter

    2. Use a graph to determine the ______________ from the monitoring station to the epicenter.


    Steps 3 4 5 of locating the epicenter

    Draw a circle, centered around the monitoring station with a radius _________ to the distance from the epicenter.

    Repeat two more times.

    5. The point where all three circles intersect is the location of the ______________.

    Steps 3, 4 & 5 of Locating the Epicenter


    Measuring the size of an earthquake
    Measuring The Size of An Earthquake radius _________ to the distance from the epicenter.

    • ______________ – determined by effects on people, structures, and the environment

    • _______________ – measures energy released at the source of the earthquake.


    Magnitude from amplitude
    Magnitude From Amplitude radius _________ to the distance from the epicenter.

    http://www.earthquakes.bgs.ac.uk/earthquakes/education/eq_booklet/dia_richter_scale.jpg


    Abbreviated modified intensity scale

    Intensity radius _________ to the distance from the epicenter.

    Witness observations

    I

    Felt by very few people; barely noticeable

    II

    Felt by a few people, especially on upper floors.

    III

    Noticeable indoors, especially on upper floors, but may not be recognized as an earthquake. Hanging objects swing.

    IV

    Felt by many indoors, by few outdoors. May give the impression of a heavy truck passing by.

    V

    Felt by almost everyone, some people awakened. Small objects move. Trees and poles may shake.

    VI

    Felt by everyone. Difficult to stand. Some heavy items of furniture move, plaster falls. Slight damage to chimneys possible.

    VII

    Slight to moderate damage in well-built, ordinary structures. Considerable damage to poorly built structures. Some walls may fall.

    VIII

    Little damage in specially built structures. Considerable damage to ordinary buildings, severe damage to poorly built structures. Some walls collapse.

    IX

    Considerable damage to specially built structures, buildings shifted off foundations. Noticeable cracks in ground. Wholesale destruction. Landslides.

    X

    Most masonry and frame structures and their foundations destroyed. Ground badly cracked. Landslides. Wholesale destruction.

    XI

    Total damage. Few, if any, structures standing. Bridges destroyed. Wide cracks in ground. Waves seen on ground.

    XII

    Total damage. Waves seen on ground. Objects thrown up into air.

    Abbreviated Modified ________ Intensity Scale


    Did you feel it
    Did You Feel It? radius _________ to the distance from the epicenter.

    http://earthquake.usgs.gov/eqcenter/dyfi.php


    Earthquake hazards

    ________________ radius _________ to the distance from the epicenter.

    ________________

    ________________

    Ground shaking

    _______________

    Ground Rupture

    Earthquake Hazards


    Shaking

    http://www.abag.ca.gov/bayarea/eqmaps/gif99/bayas06m.gif radius _________ to the distance from the epicenter.

    Shaking


    _________________ radius _________ to the distance from the epicenter.

    http://www.tulane.edu/~sanelson/images/liquefaction.gif

    Niigata Earthquake, Japan, 1964:

    Tilting of apartment buildings

    http://cee.uiuc.edu/sstl/education/liquefaction/Pictures/APTS.jpg


    Asian Earthquake and Tsunami of 2004 radius _________ to the distance from the epicenter.What Happened and Why?

    Magnitude 9 earthquake

    • Largest earthquake since the 9.2 magnitude Alaskan earthquake (1964)

    • Energy release equivalent of 23,000 atom bombs such as the one that destroyed Hiroshima

    • Why did it occur here?


    Wind generated waves vs tsunamis
    Wind-generated Waves vs. Tsunamis radius _________ to the distance from the epicenter.


    Earthquakes and tsunamis
    Earthquakes and Tsunamis radius _________ to the distance from the epicenter.

    What, besides earthquakes, can cause a tsunami?


    Tsunami risk in california
    Tsunami Risk in California radius _________ to the distance from the epicenter.

    • California is at risk of tsunamis that are generated locally and from a distance.

    • 1964: 10 killed and 35 injured when tsunami from the 1964 Alaska earthquake reached Crescent City (Oregon/CA border).

    • A Cascadia earthquake (an earthquake up in ____________ or ____________ could bring a tsunami to Northern CA in ~ 15 minutes.


    Short term prediction
    Short-term Prediction radius _________ to the distance from the epicenter.

    • Precursors: May or may not occur

      • Uplift

      • Foreshocks

      • Anomalous animal behavior

      • Changes in water levels in wells

      • Release of radon gas

      • Changes in velocity of P waves


    Long range forcasting
    Long-Range Forcasting radius _________ to the distance from the epicenter.

    • Based on knowledge of when and where past earthquakes have occurred.

      • Paleoseismology –

        _________________________________________

        _________________________________________

      • Seismic gaps-

        _________________________________________

        _________________________________________


    Bay area eq probabilities
    Bay Area EQ Probabilities radius _________ to the distance from the epicenter.

    Hayward – Rodgers Creek Faults have the highest probabilities

    Forecasting (probability) vs. prediction

    Source: USGS


    Paleoseismology the study of prehistoric earthquakes
    Paleoseismology - the study of prehistoric earthquakes.  radius _________ to the distance from the epicenter.

    http://www.tulane.edu/~sanelson/images/paleosseis.gif

    http://pubs.usgs.gov/fs/1999/fs152-99/images/faults.jpg


    M7 1868 hayward earthquake
    M7 1868 Hayward earthquake radius _________ to the distance from the epicenter.

    • 30 fatalities, 5 in San Francisco (12th most lethal US earthquake)

    • $350,000 (>$5-100M in 2007 dollars) in damage in San Francisco alone

    • Extensive damage in San Leandro, Hayward, and Fremont (total population less than 2000)

    • Bay Area population was 260,000 (it is now 27 times larger)

    Source: USGS


    1868 Hayward radius _________ to the distance from the epicenter.

    Earthquake

    Source: USGS

    38°

    37.5°

    -121°


    Earthquake of m 6 8 on the hayward fault
    Earthquake of M > 6.8 on the Hayward Fault radius _________ to the distance from the epicenter.?

    • A major earthquake today on the Hayward fault

    • would impact more than 5 million people and

    • Cause estimated total economic losses to residential and commercial properties would likely exceed $165 billion.

    • Other factors, such as fire, damage to infrastructure and related disruption would substantially increase the loss

    http://www.usgs.gov/newsroom/article.asp?ID=1899&from=rss


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