The following digital data sets are available from the
- 1933 - 1986 North and
Central American Earthquakes - a
collection of 1,477 mostly three-component station recordings from about 500 earthquakes.
These data represent all of the available North American and Hawaiian records written by
Studies - recordings collected by the NSMP from non-earthquake
Terminology, processing software, data formats, and download
- Uncorrected vs Corrected data - the term
"uncorrected" indicates that a digitized (or digitally recorded) time series has
received no processing that involves any hypotheses as to the character or frequency
content of the ground motions or recording instruments. An "uncorrected"
analog-recorded time series has been corrected only for uneven film transport with time
and for transverse motion of the film as it moved longitudinally through the recorder; it
has been shifted to have zero mean; and it has been translated from digitization units to
units of cm/sec/sec (ordinates) and seconds (abscissas). The "correction"
process applies bandpass filters (removing noise contamination) and instrument correction
(removing the effects of frequency-dependent instrument response) to a time series. For a
more complete discussion of the processing steps for corrected data see DATA PROCESSING].
- The first line of each data file contains an integer in the
first column followed by text that indicates what type of data are contained in the file:
"1 UNCORRECTED ACCELEROGRAM" (sometimes referred to as Vol 1), "2 CORRECTED
ACCELEROGRAM" (Vol 2), "3 CORRECTED VELOCITY" (Vol 3), "4 CORRECTED
DISPLACEMENT" (Vol 4), "5 RESPONSE SPECTRA" (Vol 5), or "6 FOURIER
AMPLITUDE SPECTRA OF CORRECTED ACCELERATION" (Vol 6).
- Software, named "BAP", that will
correct the time series is also available from the NSMP web site.
- SMC data
format - a general description of the SMC data format currently used for NSMP
- Download Instructions: Compressed data files
from different earthquakes but from the same station have the same names. Download files
from different earthquakes to different directories to avoid overwriting. You will
need a program that decompresses and "unzips" the data.
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This page was last modified on March 19, 2014.