L Braile, 9/12/09, AS-1 Seismograph Workshop, San Antonio

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Where did our waves come from?
L Braile, 9/12/09, AS-1 Seismograph Workshop, San
Antonio
http//web.ics.purdue.edu/braile/new/Where.ppt
Exploring Planet Earth
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Where did our waves come from?
1. Where is source? a. Seismicity map b.
Epicenter to station distance c. Hypocenter
information (latitude, longitude, depth,
origin time), magnitude, damage/impact d.
Accessing earthquake data
http//web.ics.purdue.edu/braile/edumod/eqdata/eq
data.htm
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Where did our waves come from?
2. How did the waves get to our seismograph? a.
Earth structure b. Wave propagation through the
Earth c. Seismic wave phases d. Seismic Waves
software
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1. Where is source? IRIS Seismic
Monitor http//www.iris.edu/seismon/
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IRIS Earthquake Browser http//www.iris.edu/servl
et/eventserver/map.do
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IRIS Seismographs in Schools Interactive
Earthquake Map http//www.iris.edu/hq/ssn/events
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Displaying earthquake epicenters using Google
Earth http//neic.usgs.gov/neis/epic/kml/
http//neic.usgs.gov/neis/epic/epic_global.html
(USGS earthquake search)
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USGS Earthquake Site http//earthquake.usgs.gov/
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USGS M5 Recent Earthquake List http//earthquake.
usgs.gov/eqcenter/recenteqsww/Quakes/quakes_big.ph
p
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USGS Earthquake Search http//neic.usgs.gov/neis/e
pic/epic.html
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IRIS Event Search http//www.iris.edu/quakes/event
srch.htm
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2. How did the waves get to our seismograph?
Earth Structure and Properties
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Seismic Wave Propagation (slinky, human wave
demo, seismic wave animations, seismograms,
seismic waves software) http//web.ics.purdue.edu
/braile/new/SeismicWaves.ppt  
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Refraction of light by water
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Refraction
Refraction
PKP
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(No Transcript)
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Exploring Planet Earth
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Epicenter Plotting year long activity map
practice that engages students in global
earthquake activity
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Seismograms recorded by your seismograph from
locations around the world
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Using the Seismic Eruption Software
Seismic-Eruption software (Free!,
Windows)Introduction and NavigationCalifornia
EarthquakesSo. California EarthquakesFrequency-M
agnitude Analysis - CaliforniaNorthridge
Earthquake (map, cross section)Aftershock
s (Denali, Landers)

• The Seismic Eruption software
• http//bingweb.binghamton.edu/ajones/

Exploring Planet Earth
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The Seismic Waves program

• From Alan Jones, SUNY, Binghamton
• http//bingweb.binghamton.edu/ajones/

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The Seismic Waves program Uses speeded-up time
views of wavefronts to illustrate wave
propagation through the Earth. Note reflection,
refraction and wave conversion at layer
boundaries. Seismograms show arrivals of
various phases (wave types and paths). Wave
energy/propagation represented by wavefronts.
Raypaths show direction of travel of a specific
point on the wavefront.
Earthquake

Wavefront
Cross Section Through Earth
Ray Path
Stations for Seismograms
Seismograph
Ray Path is perpendicular to wavefront
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Practice/DemonstationThe Seismic Waves Program
Earthquake

Wavefront
Cross Section Through Earth
Ray Path
Stations for Seismograms
Seismograph
Ray Path is perpendicular to wavefront
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You can add views to the Seismic Waves Program
for your seismogram and other AS-1 (or other)
stations. Example M6.0 February 21, 2008 Wells,
Nevada earthquake. For this event, we have five
AS-1 seismograms recorded by IRIS Seismograph in
Schools stations!
Earthquake

Wavefront
Cross Section Through Earth
Ray Path
Stations for Seismograms
Seismograph
Ray Path is perpendicular to wavefront
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Procedure 1. In AmaSeis, navigate to the
selected event. Navigation can be performed with
the Go To Date-Time tool in the Settings menu,
or with the Forward/Backward control (see below)
opened by clicking on the green arrows on the
toolbar, or by scrolling. (You can also download
other seismograms in sac format for Seismic Waves
from the IRIS DMC using Bud/Wilber -
http//www.iris.edu/data/request.htm. )
Green Arrows
Forward/Backward toolbar
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2. Extract the seismogram and save as a sac file
(Sac is standard file format that is used by
AmaSeis). Use the standard SIS naming convention
(yymodahrmnNAME.sac).
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3. Open the Event dialog box under the Settings
menu. A. Enter the event name (use the same
event name for all seismograms that will be
included in the Seismic Waves view). B. Enter
the earthquake magnitude and, C. the earthquake
origin time and location.
A.
B.
C.
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4. Click OK in the Event Dialog box and the
seismogram will display additional information
(earthquake location and magnitude and epicenter
to station distance in degrees).
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5. Open the Event Dialog box again and click on
Create files for Seismic Waves to add the
seismogram to a folder in the SW (Seismic Waves)
folder. You can add several seismograms from
different stations for the same earthquake. For
our Wells, Nevada example, the folder is labeled
2008022114 (see below for path), the date and
hour of the event. Five seismograms have been
added to this folder.
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6. When you finish adding data to the seismogram
folder for your event (for example, the
2008022114 folder for the Wells, Nevada
earthquake data), an event file will have been
created in the SW folder (2008022114.evt in our
example, below). Double click on the folder to
open in Notepad. The evt file will have only one
STATION FILE listed. Add the additional STATION
FILES lines to the list (as below) and save.
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7. You can also change the TIME ACCELERATION and
TIME WINDOW settings (or others) in the evt file
if desired (see settings below chosen for the
Wells, Nevada earthquake seismograms). Save the
evt file.
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8. You are now ready to open Seismic Waves and
run the program for your event with the added
seismograms. The results for the Wells, Nevada
earthquake seismograms are shown on the next two
slides. The seismograms for our example are
listed below. Click on the links to download the
sac files and place in your AmaSeis folder
(create a folder called SacFiles for your
individual seismograms). You can open the
seismograms in AmaSeis and then export to Seismic
Waves using the Create files for Seismic Waves
selection in the Event Dialog box and you will be
ready to view in Seismic Waves.
http//web.ics.purdue.edu/braile/new/0802211417AZ
AZ.sac http//web.ics.purdue.edu/braile/new/08022
11418PCAZ.sac http//web.ics.purdue.edu/braile/n
ew/0802211418UPOR.sac http//web.ics.purdue.edu/
braile/new/0802211421NLNC.sac http//web.ics.purd
ue.edu/braile/new/0802211421WLIN.sac
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The Seismic Waves program showing events that can
be viewed, including the Wells, Nevada earthquake
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The Seismic Waves program showing the Wells,
Nevada earthquake seismograms from the AS-1
stations. The view includes Earth surface, Earth
cross section and seismograms.
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M6.0, February 21, 2008 Wells, Nevada earthquake
shown by large red star. S-P circles (from S-P
times from seismograms analyzed using AmaSeis for
stations PCAZ, UPOR, WLIN and NLNC red
triangles).
-130
-120
-100
-90
-80
-70
-110
50
50
40
40
30
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M4 earthquakes, 1980-2009 (Sept. 15) about
35,000 events.
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20
-130
-120
-110
-100
-90
-80
-70
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Input information (left) for Wells, Nevada
earthquake and location and S-P inferred
distances (radius in km) for seismograph stations
PCAZ, NLNC, UPOR, and WLIN.
Legend (depth of focus scale and magnitude and
data source table) for the seismicity map on
previous slide.
Map produced with IRIS event search
tool http//www.iris.edu/quakes/eventsrch.htm