Exploring Planet Earth

braile@purdue.eduwww.eas.purdue.edu/~braile

Updated October 2011

The AS-1 Seismometer and AmaSeis Software – An Effective Educational Seismograph

Larry BraileDepartment of Earth and

Atmospheric Sciences

Purdue University

IRIS Seismographs in Schools Program

http://www.iris.edu/hq/sis

http://web.ics.purdue.edu/~braile/new/AS1AmaSeis2008.ppt

The AS-1 Seismometer

The AS-1 Seismometer• Inexpensive (~$500); 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

24-Hour Screen Display

Extracted Seismogram

(developed by Alan Jones, SUNY Binghamton, NY)

IRIS AmaSeisSoftware

January 22, 2003, M7.8, Colima, Mexico earthquake recorded on an AS-1 seismograph and AmaSeis software at West Lafayette, IN. Distance = 26.01 degrees. Seismogram was filtered from 0.001 – 0.1 Hz.

.

Maintaining a catalog of recorded earthquakes is a convenient and educational exercise associated with educational seismograph operation. Data entries require observation and analysis of seismograms, retrieving information from the internet and performing simple calculations.

Monitoring Earthquakes

Determine distance from S-P time

Using the AmaSeis travel time curve tool to determine the epicenter-to-station distance from the S-P arrival times. January 22, 2003, M7.8, Colima, Mexico earthquake recorded on an AS-1 seismograph and AmaSeis software at West Lafayette, IN; Distance = 26.01 degrees.

Drawing an arc on the globe for Oaxaca EQ for TUC station.

Comparison of calculated earthquake to station distance and distance estimated from S – P times

N = 169; Standard Deviation = 1.89 degrees

http://web.ics.purdue.edu/~braile/edumod/MagCalc/AS1Results.htm

Calculating Magnitude

Inputs: Distance (degrees), Amplitude (digital units from AmaSeis screen; converted to displacement by the calculator), and wave period (seconds).

Online Earthquake Magnitude Calculator for the AS-1 Seismograph

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

Exploring Planet Earth

AS-1 Seismograph Resources

AS-1 Seismograph Information (Links):http://web.ics.purdue.edu/~braile/indexlinks/as1.htm

View Near Real Time Seismograph Displays:http://www.iris.edu/amaseis/schools/

Teaching Modules and Tutorials:http://web.ics.purdue.edu/~braile/edumod/as1lessons/as1lessons.htm

WLIN Seismograph Earthquake List:http://web.ics.purdue.edu/~braile/edumod/as1lessons/InterpSeis/EqList.xls

WLIN Earthquake data for download (as large as 50MB):http://web.ics.purdue.edu/~braile/new/2004.zip also, 2005.zip, 2006.zip, 2007.zip, 2008.zip, 2009.zip, 2010.zip

Instructions for downloading 2003 (etc.) data to the AmaSeis folder on your computer:http://web.ics.purdue.edu/~braile/edumod/as1lessons/UsingAmaSeis/download2003.htm