Thread: Magnitude calculation for the M8.1 April 1, 2007 Solomon Islands earthquake

The M8.1 April 1, 2007 Solomon Islands earthquake provides a good
opportunity to calculate the MS magnitude from your AS-1 seismogram. Or,
use the WLIN seismogram (shown in the attachment and available for
download at SpiNet, http://www.scieds.com/spinet/). If your station is
in the western US, an mb magnitude can also be calculated. For central
and eastern US stations, the first arrival is P-diffracted (see map of
theoretical travel times at:
http://neic.usgs.gov/neis/eq_depot/2007/eq_070401_aqbk/neic_aqbk_t.html).
The epicenter to station distance for the WLIN station is 115.29
degrees. The magnitude can be calculated directly in AmaSeis or from
the AS-1 online magnitude calculator
(http://web.ics.purdue.edu/~braile/edumod/MagCalc/MagCalc.htm). For the
WLIN seismogram, the MS magnitude is 7.7. The official USGS MS
magnitude is 7.8 calculated by averaging values from 157 stations
(http://earthquake.usgs.gov/eqcenter/eqinthenews/2007/us2007aqbk/).

-Larry Braile


--
Lawrence W. Braile, Professor and Department Head
Department of Earth and Atmospheric Sciences
550 Stadium Mall Drive
Purdue University
West Lafayette, IN 47907-2051
(765) 494-5979 (O), (765) 496-1210 (Fax)
E-mail: braile<at>purdue.edu <braile<at>purdue.edu>
Web page: http://web.ics.purdue.edu/~braile
http://web.ics.purdue.edu/%7Ebraile
Departmental web page: http://www.purdue.edu/eas/
http://www.purdue.edu/eas/
SAGE web page: http://www.sage.lanl.gov/