Each figure is a plot of one of the raw digital data files. All components of each record are plotted. The absence of the traces of components 2 and 3 signifies that only the vertical component was recorded by the instrument at that time.
The upper right hand corner label in large letters is the computer file specification. The three characters to the right of the period are the three-character instrument code. The first 8 characters of the specification are time of instrument trigger starting with Julian day. Because of the limit to the number of characters used in a computer filename, the time in seconds of the arrival is abbreviated to a letter representing one of the twenty 3-second intervals into which 60 seconds is divided. The 8th character is a letter denoting the 3 second interval: "A" = 0 - 2 seconds; "B" = 3 - 5 seconds, etc. The 9th character (character immediately to the left of the period) specifies motion/component information. Components 1 - 3 are the three components of acceleration, components 4 - 6 are the three components of velocity, etc. Where the three components of an arrival are referred collectively, the component/motion number will either be the first or last component of that motion, i.e., three components of velocity will be "4" or "6". The labels of the heading information refer to the following parameters.
Time = | The time of the first sample of the record. |
EVN = | The instrument count of the current event since last reset. |
DUR = | The duration of the record in seconds. |
S.R. = | The sampling rate in samples per second. |
SER = | The serial number of the instrument. |
LAT = | Station Latitude in degrees and decimal minutes. |
LON = | Station Longitude in degrees and decimal minutes. |
ELV = | Station elevation in meters. |
DIREC = | The orientations of the three orthogonal components measured in degrees. The number to the left of the "/" denotes the angle of orientation of the component measured from the zenith, and the number to the right of the "/" denotes the horizontal azimuth measured clockwise from North. |
TRNDUC = | The transducer type either "VEL" or "FBA". |
COIL = | The coil or motor constant of the transducer in volts per unit of motion. |
FO = | The natural frequency of the transducer in hertz. |
DAMP = | The damping coefficient of the transducer. |
FC, AAF = | The corner frequency of the instrument anti-aliasinq low-pass filter. The instrument C9V has a corner of 70 Hz and is labeled 50 Hz in error. |
ORDER, AAF = | The order of the Butterworth anti-aliasing filter. Order = 5 is equal to 30 dB per octave roll-off above the corner frequency. |
SEC: = | The time in seconds of the origin of the time-axis as plotted. This time may be greater than the seconds value indicated in the heading of the first recorded sample if several of the initial samples have been skipped for plotting convenience. |
CLK. CORR. = | The clock corrections in seconds to be subtracted from the times indicated on the plot to yield true time. True Time = Record (Labeled) time - Clock correction. |
[ The Appendix figures are not available online ]