The sliced ICEMELT broadband data, Department of Terrestrial Magnetism, Carnegie Institution of Washington.
These tapes contain sliced SAC files for earthquakes recorded on the ICEMELT experiment. The data were recorded on STS-2 seismometers owned by The Department of Terrestrial Magnetism, Carnegie Institution of Washington. The experiment PIs were Sean Solomon and Ingi Th. Bjarnason (Ingi Bjarnason is now at the Science Institute, University of Iceland). The data was orginally recorded on reftek disks, but the continuous data were converted to SEGY using the program ref2SEGY, and then sliced and converted into SAC data with earthquake information in the header. This dataset only contains the sliced SAC data and the SEGY triggered data, although DTM still has copies of the original continuous data.
The directories under "slicedata.1, slicedata.2, etc." contain directories called akud, bre, etc. These directories are named by the station. Each directory contains subdirectories containing sliced earthquake data in SAC format. The data is in a directory named by the julian day of the earthquake (e.g., slicedata.1/bre/94042). The sac files in the julian day directories are named after the starting time of the earthquake, e.g.:
slicedata.1/bre/94042/21.17.31.bre.1.sac
slicedata.1/bre/94042/21.17.31.bre.2.sac
slicedata.1/bre/94042/21.17.31.bre.3.sac
The channels marked .1.sac are vertical, .2.sac are north, and .3.sac are east.
There is also a directory called "nolock". This contains SAC data for periods when the GPS clock was found to be not operating, thus the absolute timing is not accurate.
The log files from reading the continuous tapes using ref2SEGY are in iceroot. For example, iceroot/akud/94322-95047 contains the log file (I0660.log) from the period covering 94322-95047. These directories also contain the SEGY triggered data. The .02 channel is the triggered data sampled at 50 sps, in order to record local microearthquakes. The .06 channel is the triggered low-gain channel, at 10 sps. e.g.,
iceroot/akud/94297-94322/R321.06/21.25.12.0660.4
iceroot/akud/94297-94322/R321.06/21.25.12.0660.5
iceroot/akud/94297-94322/R321.06/21.25.12.0660.6
iceroot/akud/94297-94322/R319.02/00.59.58.0660.1
iceroot/akud/94297-94322/R319.02/00.59.58.0660.2
iceroot/akud/94297-94322/R319.02/00.59.58.0660.3
The .4 and .1 channels are vertical, .5 and .2 channels are north, and .6 and .3 channels are east. Note that for the iceroot triggered data for station REYV ONLY, the horizontals will need to be multiplied by -1 (there was a polarity reversal found at reyv, which was corrected in the processing to SAC but is still present in the SEGY data).
The file containing the list of sliced earthquakes is called icemelt.loc.
The station names and locations are as follows:
Station Lat. Long. Elev(m) Location
Iceroot klu 65.7817 -21.5177 010 Kluka,Bjarnarfirdi,Strondum Iceroot bre 66.2896 -16.4253 010 Brekka, Melrakkaslettu Iceroot kaf 63.9465 -17.6862 050 Kalfafell, Fljotshverfi Iceroot akud 65.6859 -18.0999 025 Akureyri Digital DTM broadband iceroot nyd 64.7345 -18.0688 800 Nyidalur iceroot birh 65.0073 -14.6189 150 Birkihlid iceroot skot 65.3412 -17.2467 405 Svartarkot iceroot hoff 64.3967 -15.3404 050 Hoffell iceroot blol 65.2310 -19.7178 490 Blondulon iceroot asbs 65.7047 -14.9171 030 Asbrandsstadir iceroot reyv 64.1271 -21.9040 050 Reykjavmk iceroot hrau 66.1186 -20.0987 000 iceroot mdal 66.1237 -23.2609 030 Middalur iceroot hnjo 65.5626 -24.1531 015 Hnjotur iceroot askj 64.9844 -16.6754 720 Askja iceroot ljop 64.0249 -19.0201 580 Ljotipollur
Tape 1. Created by:
tar cvf /dev/rmt/0cn slicedata.2 slicedata.4 slicedata.5
Tape 2:
tar cvf /dev/rmt/0cn slicedata.1 slicedata.6 slicedata.7 slicedata.8
slicedata.9
Tape 3:
tar cvf /dev/rmt/0cn iceroot nolock slicedata.3
Questions can be addressed to the following people:
Randy Kuehnel, DTM, kuehnel@dtm.ciw.edu
Cecily Wolfe, DTM, cecily@dtm.ciw.edu