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:
- first column: epicentral distance [deg]
- second column: minutes of travel time
- third column: seconds of travel time
(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.)
eof.