Reference Data

Travel times from printed tables are used as reference, rather than the output of other software. This has the advantage that these tables are publicly available to everybody, so everybody can repeat the validation with precisely the same reference data without further discussion of additional errors which may be introduced by using different compilers or different hardware. The disadvantage is that printed tables usually contain travel times for a limited number of focal depths and epicentral distances only, and with a relatively large roundoff error.

Since I have typed the reference data files by hand, I include these files into the TTBOX distribution in order to make it possible to identify typing errors (which, to my best knowledge and after several tests, do not exist) and to make my validation procedure fully transparent. The path to the data directory will be returned by MKTTBOXDATA once TTBOX is installed.

The following travel time data files are given in the data directory of the TTBOX distribution:

iasp91_P_0km.txt
P travel times as given in the IASP91 booklet by Kennett (1991) on pages 6 to 12 for epicentral distances in the range 0° to 99° for focal depth 0km.
Format:
(this is the format required by MKTTBOXVALID)
iasp91_S_0km.txt
S travel times: 0km focus, Epicentral distance 0° to 99°.
iasp91_PKPab_0km.txt
PKPab travel times for epicentral distances 145 to 180 deg and 0km focus from the IASP91 booklet
iasp91_PKPbc_0km.txt
PKPbc travel times for epicentral distances 145 to 155 deg and 0km focus from the IASP91 booklet
iasp91_PKPdf_0km.txt
PKPdf (PKIKP) travel times for epicentral distances 114° to 180° and 0km focus from the IASP91 booklet.
iasp91_SKSdf_0km.txt
SKSdf (SKIKS) travel times for epicentral distances 104° to 180° and 0km focus from the IASP91 booklet.
iasp91_PcP_0km.txt
PcP travel times for epicentral distances 0° to 98° and 0km focus from the IASP91 booklet.
jb_P_0km.txt
P travel times from Jeffreys & Bullen (1940) for distances 0° to 99° (only integer distances) and 0km focus.
jb_S_0km.txt
S travel times from Jeffreys & Bullen (1940) for distances 0° to 100° (only integer distances) and 0km focus.
jb_PcP_0km.txt
PcP travel times from Jeffreys & Bullen (1940) for distances 0° to 98° (only integer distances) and 0km focus.

JB files are given as comparison between the two standard models IASP91 and JB: It is a minimum requirement that travel times computed by TTBOX differ from IASP91 by less than the difference between these standard models. It should be possible to distinguish these models by comparing their travel times.

The following files contain travel times computed with programs onset and TauP Toolkit (see section on Results of other Software for details). The data therein were also be tested against the IASP91 Booklet by Kennett (1991), which still serves as reference.

onset_times_0km.txt
P, PKPdf, S and SKSdf travel times computed with onset. This file contains the epicentral distance (degrees) in the first column, P and PKPdf travel time in the second column (times are P up to 98° and PKPdf from 125° onwards), ellipticity correction for P in the third column, S and SKSdf travel times in the fourth (times are PS up to 98° and SKSdf from 125° onwards), and ellipticity correction for S in the fifth column. The ellipticity corrections have to be subtracted from the travel times to get the spherical traveltimes which alone should be compared with TTBOX times. All travel times in the file are in seconds and valid for a surface focus. Both source and station were assumed to be at the equator.
These data were computed on a Sun Ultra 5_10 under Solaris 5.8.
TauP_times_P_0km_web.txt
P travel times computed by the TauP Toolkit. This file contains epicentral distance (degrees) in the first column and P travel times (seconds) in the second column. Times were calculated using the web interface at http://www.le.ac.uk/gl/pdt/teaching/java/TauP/taup.html. If the toolkit produced more than one time for a certain distance, the first was copied.
These data were computed using a Suse Linux PC with SunJava2-1.3.1.
TauP_times_PKP_0km_web.txt
raw data file from which files for PKPab and PKPbc were constructed (TauP Toolkit does not distinguish PKPab and PKPbc)
TauP_times_PKPab_0km_web.txt
PKPab travel times computed by the TauP Toolkit. This file contains epicentral distance (degrees) in the first column and PKPdf travel times (seconds) in the second column. Times were calculated using the web interface at http://www.le.ac.uk/gl/pdt/teaching/java/TauP/taup.html. If the toolkit produced more than one time for a certain distance, the first was copied.
These data were computed using a Suse Linux PC with SunJava2-1.3.1.
TauP_times_PKPbc_0km_web.txt
PKPbc travel times computed by the TauP Toolkit. This file contains epicentral distance (degrees) in the first column and PKPdf travel times (seconds) in the second column. Times were calculated using the web interface at http://www.le.ac.uk/gl/pdt/teaching/java/TauP/taup.html. If the toolkit produced more than one time for a certain distance, the first was copied.
These data were computed using a Suse Linux PC with SunJava2-1.3.1.
TauP_times_PKPdf_0km_web.txt
PKPdf travel times computed by the TauP Toolkit. This file contains epicentral distance (degrees) in the first column and PKPdf travel times (seconds) in the second column. Times were calculated using the web interface at http://www.le.ac.uk/gl/pdt/teaching/java/TauP/taup.html. If the toolkit produced more than one time for a certain distance, the first was copied.
These data were computed using a Suse Linux PC with SunJava2-1.3.1.

(The TTBOX results shown in the following sections were computed on Intel XEON architecture with MatLab 6.1.0.450 (R12) under Suse Linux.)


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