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Science for Planet Earth
[email protected]/~braile
April 2010
A Decade of Earthquake Monitoring with an Educational Seismograph
Larry BrailePurdue University
SSA Meeting 2010
The AS-1 Seismometer
The AS-1 Seismometer
• Inexpensive (~$600); easy to set up and use• Demonstrate how a seismograph works• “Make your own earthquake”• Monitor earthquakes – local (~M3+), regional
(~M5+), worldwide (~M6.5+)• Connects to IRIS data archiving and analysis
software (written by Alan Jones) on Windows computer; maintain EQ catalog
• Display, filter and analyze seismograms• Calculate epicenter-to-station distance from S-P
times; calculate magnitude
Oil Damping Mechanism
Mass (plus magnet)
Magnet and Coil
Boom
SpringHinge
Magnetic Damping
MechanismMagnetic Damping
Mechanism
The WLIN AS-1 seismometer was installed in basement of home in West Lafayette, Indiana on January 1, 2000 and immediately recorded an earthquake (~M5) from Quebec.
Objectives:
Support the IRIS Seismographs in Schools (SIS) program and use of the seismograph by educators.
Monitor earthquakes and provide sample and comparison data.
Experience with AS-1 and software; test and evaluate seismograph, software and recordings and suggest improvements.
The AmaSeis software to operate the AS-1 was written by Alan Jones. AmaSeis provides display, filtering, analysis and archival.
Calibrated the AS-1 (for calculating magnitudes) with assistance of Bob Hutt (USGS), Tim Long (GT), Alan Jones (Binghamton), John Lahr (USGS).
Ten Years of Recording with the AS-1 Seismometer
Experience with the AS-1 seismograph - Noise Levels
Low NoiseJune 6, 2008
Sept. 6, 2008 - Microseisms
Tropical Storm Hanna off coast of N and S Carolina
AS-1 Seismograph - Approximate Maximum Distance of Recording versus Magnitude
25
55
110
140
180
105
75
020406080
100120140160180
3.5 - 4.0
4.1 - 4.5
4.6 - 5.0
5.1 - 5.5
5.6 - 6.0
6.1 - 6.5
6.6 - 7.0
>7.0
Magnitude Range (Mw)
Ap
pro
xim
ate
Max
imu
m
Dis
tan
ce (
Deg
rees
)
AS-1 Seismograph – Approximate Distance of Recording versus Magnitude
Comparison of WLIN AS-1 seismogram with SFIN (about 10 km from WLIN) STS 2 seismogram for 2010 Haiti earthquake
WLIN AS-1 vertical component, low pass filtered twice with 10 s period cutoff
EarthScope SFIN vertical component, low pass filtered with 10 s period cutoff
Example of WLIN Station Earthquake List
WLIN AS-1 Seismograph 24-hour screen display for August 15-16, 2007
Example seismograms (local, regional, global, phases, recent, significant events)
AmaSeis 24-hour seismograph display – M8.1 Samoa Islands earthquake, September 29, 2009
AmaSeis seismogram display – M8.1 Samoa Islands earthquake, September 29, 2009
AmaSeis seismogram display, ~20 s period surface waves – M8.1 Samoa Islands earthquake, September 29, 2009
AmaSeis 24-hour seismograph display – M4.0 Mt. Carmel, Illinois earthquake, April 21, 2008
AmaSeis seismogram display – M4.0 Mt. Carmel, Illinois earthquake, April 21, 2008
AmaSeis seismogram display – M7.9 Kuril Islands earthquake, November 15, 2006
AmaSeis seismogram display – M7.9 Kuril Islands earthquake, November 15, 2006 – High pass filtered with 2 s period cutoff to see aftershocks
M6.3 Argentina deep focus (570 km) earthquake, Sept. 3, 2008
PpP P
PS
M6.3 Argentina deep focus (570 km) earthquake, Sept. 3, 2008
M6.3 Argentina deep focus (570 km) earthquake, Sept. 3,
2008 – AmaSeis Travel Time curve display
P pP
PP
S
AmaSeis seismogram display – M4.9 N. Utah earthquake, April 16, 2010
AmaSeis seismogram display – M6.0 Wells, Nevada earthquake, Feb. 21, 2008
M6.0 Wells Nevada earthquake, Feb. 21, 2008 – AmaSeis Travel Time curve
display
P S
AmaSeis seismogram display – M4.6 Evansville, Indiana earthquake, June 18, 2002
M4.6 Evansville, Indiana earthquake, June 18, 2002, AmaSeis Travel Time curve display
Actual epicentral distance = 2.59 degrees
Time (minutes)
AmaSeis seismogram display – M8.8 Chile earthquake, February 27, 2010
AmaSeis seismogram display – M7.2 N. Baja earthquake, April 4, 2010
Comparison of calculated earthquake to station distance and distance estimated from S – P times
N = 169; Standard Deviation = 1.89 degrees
MS Magnitudes: N = 270; Standard Deviation = 0.25 magnitude units.mb Magnitudes: N = 520; Standard Deviation = 0.26 magnitude units.mbLg Magnitudes: N = 34; Standard Deviation = 0.35 magnitude units.
Comparison of AS-1 and USGS Magnitudes
Comparison of AS-1 and USGS Mw Magnitudes
AS-1 mb, MS and mbLg magnitudes correlate well with M (Mw, moment magnitude) except for the largest earthquakes
Use of real and relevant scientific data, observing in real time
Students and teachers operate seismograph and record their own data
Real time monitoring – display in classroom
Analyze and interpret seismograms and obtain accurate information about earthquakes from the seismograms – phases, epicentral distance, earthquake magnitude
Connect to other discovery and learning activities (seismic waves, Earth structure, plate tectonics, seismicity, earthquake hazards)
WLIN data online – can be used with AmaSeis on any Windows computer (does not need to be connected to a seismometer) – Data files:http://web.ics.purdue.edu/~braile/edumod/as1lessons/as1lessons.htm (see #13), EQ List: http://web.ics.purdue.edu/~braile/edumod/as1lessons/InterpSeis/EqList.xls
Key aspects of earthquake recording with an educational seismograph and the Seismographs in Schools program
Thanks to John Lahrfor assistance, innovations
and insights for the educational seismology
program, his many other contributions to Earth
science education, and for being a great friend and
colleague!
Science for Planet Earth
[email protected]/~braile
April 2010
References and Resources
This PPT: http://web.ics.purdue.edu/~braile/ppt/ssa.ppt
IRIS Seismographs in Schools: http://www.iris.edu/hq/sis Using AmaSeis Tutorial:
http://web.ics.purdue.edu/~braile/edumod/as1lessons/UsingAmaSeis/UsingAmaSeis.htm
AS-1 Reosurces (See Number 13 for link to WLIN AS-1 continuous data and Excel spreadsheet earthquake list): http://web.ics.purdue.edu/~braile/edumod/as1lessons/as1lessons.htm
Interpreting Seismograms Tutorial: http://web.ics.purdue.edu/~braile/edumod/as1lessons/InterpSeis/InterpSeis.htm