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\fBData Report
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for
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The 1988-89 PASSCAL Basin and Range
.br
Passive-Source Seismic Experiment 
.br
Part II:  Small Aperture Array Data\f
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\fIsubmitted by
Thomas J. Owens and Daniel E. McNamara
University of South Carolina
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for the
PROJECT SCIENCE TEAM\f
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\fB*** PASSCAL DATA REPORT #90-002 ***\f
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ABSTRACT
.sp
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This report describes the data from the
1988-89 PASSCAL Basin and Range Passive Source Seismic Experiment,
collected by the small aperture array
consisting of 13 REFTEK digital recorders with
12 3-component 1 Hz seismometers and one
3-component intermediate period seismometer.
A total of 53 seismic events with known locations,
and many smaller local events without locations
are included in this data distribution.
Data formats, auxiliary information, calibration
information, and organization of the distribution
data tape are discussed.
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.NH
Introduction
.PP
The 1988-89 PASSCAL Basin and Range Passive Source Seismic Experiment
consisted of two deployments.
The Large Aperture Array of 7 PASSCAL data recorders
was deployed from August 17, 1988 until April 29, 1989.
The Large Aperture Array used 3-component mid-period
sensors, and each site operated independently
in a triggered mode.
A Small Aperture Array, consisting of the Lawrence
Livermore National Laboratory (LLNL) Configurable Seismic Monitoring
System (CSMS), was deployed from August 1988 through
October 1988.
The Small Aperture Array used primarily 3-component short-period 
sensors, and operated in a continuous recording mode
with digital telemetry to a central recording site.
.PP
The study area was in the region of the Stillwater Range
in Nevada (see Figures 1 and 2), and was chosen to coincide
with the center of the crossing refraction profiles
of the 1986 PASSCAL Basin and Range Lithospheric
Experiment.
This location was chosen so that a comparison of
lithospheric modeling techniques, principally
receiver function modeling, and refraction and reflection
modeling, could be compared in a coincident study area.
.PP
The experiment team consisted of a field crew,
and project scientists.
The field crew, Randy Kuehnel and Thom Morin, deserve
a great deal of credit for the success of the field
operation.
Their consistent dedication and effort
made both array deployments operate as
smoothly as possible, and aided greatly in the
preliminary data processing.
The project scientists consisted of
T.J. Owens, D. McNamara (University of Missouri, 
now at University of South Carolina),
G.E. Randall, K.F. Priestley (both at University of Nevada-Reno),
and G. Zandt (at the LLNL Institute for Geophysics and Planetary
Physics).
.PP
The instrumentation for the Small Aperture Array
consisted of the LLNL CSMS system, with 13
continuously recorded digitally telemetered 
stations. The short-term, small-aperture array consisted
of four three-station sub-arrays located about a central 
recording site. This central site was co-located with a station
from the large aperture array (FNC)(Figure 2), and operated with
mid-period (Kinemetrics SV-1 and SH-1) seismometers.
The  remaining 12 stations used short period (Geotech
S-13) 3-component seismometers.
Time information was derived from an OMEGA clock
at the central recording site, and rebroadcast
to synchronize the field sites.
The field sites used digital telemetry via radio
links to pass the 100 sample per second 
data to the central recording site,
where data was continuously recorded onto either
optical disk or 8 mm tape for later demultiplexing
and analysis.
.PP
The Small-Aperture Array was centered on the Large-Aperture
Arrays FNC site (Figure 2; Table 1) and was located on the eastern 
side of the Buena Vista Valley on a westward dipping alluvial 
fan of Quaternary age. This deposit is characterized by poorly 
sorted, unconsolidated sands, silts and gravels derived
from the adjacent Stillwater Range. Bedrock was estimated 
to be at a depth of no less than 30 meters (Johnson, 1977).
.PP
This data report summarizes the data available
from the Small Aperture Array.
The Large Aperture Array has been previously described
in Part I of this report. 
A complete Large Aperture Array data report 
and digital data is available from the 
IRIS Data Management Center in PASSCAL
Data Report #90-001 (Owens and Randall, 1990).
The standard distribution tape for this experiment is trace data
for located seismic events.  Supplementary raw data for
unlocated events is also available to interested researchers.
.NH
Description of Data Distribution
.PP
The Small-Aperture Array data has been provided to IRIS in one
set which is a tar file of a UNIX file structure.  The contents of
distribution is described below.  The entire data distribution
totals just over 277 Mbytes in size.
.PP
All of the trace data in this data distribution is in SAC format. 
SAC is an acronym for "Seismic Analysis Code", a general purpose
software package for the manipulation of seismic data developed at
Lawrence Livermore National Laboratory (LLNL).  It is available
through IRIS or LLNL.  
We primarily used trigger times from the LAA and the
Quick Determination of Epicenters (QDE)
listings obtained through the toll-free modem number of the
National Earthquake Information Center (NEIC)
to determine appropriate time windows for the SAA.  
Local and regional
events not found in the QDEs were often found in the Nevada
Regional Catalog distributed by the Seismological Laboratory of
the University of Nevada-Reno.
Time windows ranging from three to fifteen minutes, depending on
the nature of the event, were read from the 8 mm tapes.
Due to hardware imcompatibilities, data recorded on optical
disk early in the experiment were never recovered.
.PP
We were able to identify most seismic events using this method,
however many smaller local events or mine blasts could not be
assigned a location from either catalog.  These were retained and
are distributed
as the "Raw Data Distribution" described
below.  All events with known locations were assigned an event
number and trace data from these events make up
the primary data distribution.  
This data is termed the "Numbered Event Data" and is
described in the next section.
.NH 2
Numbered Event Data
.PP
A total of 47 separate seismic events with known locations make
up the numbered event data.  
We used the same event numbers used by Owens and Randall in Part I
of this report.  Two events (215 and 216) were added to
the master event list.
These events are listed in chronological order in Table 2.
Our numbering scheme for the LAA was as follows:
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center, tab(|);
ll.
001-299|P-wave triggers
701-999|Teleseismic S-wave Triggers
301-599|Other Teleseismic Body Wave Triggers
.TE
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.PP
In the cases of an S-wave trigger, the event number assigned was
the P-wave trigger number plus 700 and for the other teleseismic
triggers, the event numbers assigned were the P-wave trigger
number plus 300.  For example the Tonga Islands event of 10/08/88
triggered some sites on the P-wave, and S-wave.  These
were assigned event numbers 053, 753 respectively.
For the SAA teleseismic data, we were able to extract both P-wave
and S-wave windows for several events and we followed the same
numbering scheme for these events.
For the SAA data, we attempted to extract sufficiently long
windows to include all useful phases for local and regional
events.
.PP
The numbered event trace data is distributed using the following
file naming convention:
.ce
$EVT.saa/STA.C$
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Where $EVT$ is the assigned event number, column 1 in
Table 2; $STA$ is the station name, column 1
in Table 1; $C$ is the component identifier, $z$ for Vertical
component (positive up), $n$ for North component (positive north),
or $e$ for East component (positive east).
.PP
The trace data amplitudes are given in units of volts.  The
event and station latitude, longitude, and depth or elevation as
well as the proper component orientations have been entered into
the proper SAC header fields.  The numbered event data
distribution is organized in the following UNIX directory
structure:
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center, tab(|);
ccc
ccc
rnl.
Directory|Size|Description
Name|(Mb)|of Contents
=
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NV88_SAA/|277.1|Main Directory
.sp .5
\./calb|19.2|Calibration Traces
\./tele|100.8|Teleseismic events
\./others|61.6|Local and Regional Events
\./tele.std|49.5|Standardized teleseismic data
\./unlocated|42.2|Unlocated trace data
\./data_report|3.8|text and figures of this report
.TE
.ls 2
.NH 3
Teleseismic Data
.PP
A typical event recorded by the Small Aperture Array
is plotted in Figure 3.  The
NV88_SAA/tele.std directory contains the teleseismic traces
standardized to a sampling rate of 100 samples/sec and a record
length of 210 sec.  In tele.std,
the mean of each trace has been removed and a
Hanning taper applied to the first and 
last 7.5 sec of each trace.  Also,
for each event, the traces at all stations recording the event have been
synchronized to a common reference time to allow for more accurate
array analysis.  Some low signal-to-noise ratio traces and events
with other quality control problems have been discarded from this
directory.  This directory contains the data used in the research
portion of this study. 
The NV88_SAA/tele directory contains teleseismic events saved at
their original record length without the processing described above.   
.NH 3
Local/Regional Data
.PP
The NV88_SAA/others directory contains all of the trace data for
non-teleseismic events recorded by the Small-Aperture Array.
Figures 4 and 5 show typical regional and local events.
Each trace has the original sampling rate and record length.  Since we
have not used this data in our research to date, we have not made
thorough attempts to cull low signal-to-noise ratio events or
other events with data quality problems from this data set. 
.NH 2
Calibration and Quality Control
.PP
The Geotech S-13 seismometers are moving-coil electromagnetic sensors
with an nominal free period of 1 Hz.
The Kinemetrics SV-1/SH-1 sensors are moving-coil electromagnetic seismometers
with a nominal natural period of 5 seconds.
Damping resistors were added to the seismometer
circuit to obtain a nominal damping of 0.7 critical.
The data streams were filtered by the local REFTEK 97 digitizer
with a 6-pole Butterworth lowpass anti-aliasing filter with a
corner at 22.5 Hz and an analog 1-pole high pass filter with
a corner at 1 Hz.  The high pass filter could be selected or
omitted by digital commands from the CSMS central recording trailer,
but was routinely applied during this experiment.
A calibration procedure could be activated simultaneously at all
sensors from the central recording trailer.
This involved digital commands to activate the calibration coils
and inject current steps into them periodically.
This was done 9 times during the deployment.
Each calibration is contained in a separate subdirectory of the
NV88_SAA/calb directory in our data distribution.
The subdirectories are named with the Julian day and time at
which the calibration was executed with the suffix .c 
appended to indicate a calibration event.
.PP
We have not included estimated system responses for each
calibration with this data distribution.  The 0.1 Hz high
pass filter has been extremely difficult to model accurately
using our existing codes which perform time domain iterative
least squares fits of the calibration pulses (as described in
Part I of this report).  This prevents us from getting an
accurate estimate of the free period and damping for the 1 Hz
seismometers at the present time.
.PP
The telemetry process occasionally introduced spikes into the
recorded data streams.  In addition if the CSMS software detected
corrupt time stamps, then a spike with a value of 32768 counts was
put in the data stream to flag the potential problem.  This latter
type of spike is often associated with a visible tear in the
continuity of the data.
Since individual applications will determine the significance of
these data quality problems as well as the most appropriate method
of removing or avoiding these glitches, we have not attempted to
remove them from the data distributed here.  We have found that
the "rglitch" command in SAC is effective in removing single spikes
of the type that can occur in this data set.
.NH 1
Raw Data Distribution
.PP
Since events for which no catalogued location exists may still be
of interest to other researchers, we have included
them with our data distribution in a directory called
NV88_SAA/unlocated.  
In this directory, individual events are in subdirectories named
by the Julian day and time of the start of the data window.
.NH 1
Data Report Format
.PP
We have included in the directory NV88_SAA/data_report a
complete version of the text in UNIX troff format and the figures
in PostScript format.  On our Sun Microsystems workstations, the
data report may be printed using:
.ce
eqn nv88_saa.txt | tbl | ptroff -ms
.ce 0
.PP
The Figures may be printed on a PostScript printer using:
.ce
lpr figure*.ps
.ce 0
.NH 1
Acknowledgements
.PP
The CSMS equipment was provided by LLNL through internal
funding to George Zandt of LLNL-IGPP.
Sally Owens carefully read the data from the 8 mm field tapes
and did initial event identification and quality control work.
Technical, logistical and administrative assistance by
Brenda Bowman, Diane DePolo, Dan Ewert, Craig Johnston, Wally Nicks,
Sally Owens, Don Rock, and Jay Zucca was valuable.  
This project was supported by IRIS grants to the 
University of Missouri-Columbia, the University of South Carolina, 
and the University of Nevada-Reno.  
T.J. Owens was also supported by the UMC Research Council during
the Fall of 1988.  
.NH 1
References
.PP
Johnson, M., Geology and mineral deposits of Pershing County, Nevada,
Bulletin 89, Nev. Bur. Mines & Geology, 1977.
.NH 1
Data Distribution
.PP
The Data referenced in this report may be obtained through:
.DS
IRIS Data Management Center
8701 Mopac Blvd., Suite 205
Austin, TX 78759
Telephone: (512) 471-0403, 0404, or 0405
.DE
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center, tab(|);
c s s s s
c s s s s
c s s s s
c c c c c
c c c c c
l n n n l.
TABLE 1
=
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Small Aperture Array
Station Locations
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Station Name|Latitude|Longitude|Elevation
|(Deg. N)|(Deg. W)|(meters)
.sp .5
=
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ctr|40.096|117.885|1487
a1|40.087|117.868|1585
a2|40.082|117.830|2085
a3|40.073|117.851|1762
b1|40.088|117.934|1387
b2|40.087|117.906|1466
b3|40.065|117.908|1597
c1|40.119|117.914|1341
c2|40.125|117.887|1402
c3|40.106|117.897|1414
d1|40.075|117.995|1439
d2|40.133|117.974|1242
d3|40.160|117.932|1414
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center, expand, tab(|);
csssssss
csssssss
cccccccc
cccccccc
ccnnnnnl.
TABLE 2
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Event Locations
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=
Evt|Date|Origin|Latitude|Longitude|Depth|Mb|Region
ID||Time|(Deg)|(Deg)|(Km)
_
.sp
001|08/17/88|015911.1|7.658S|107.264E|58|6.0|JAVA.
007|08/17/88|170000.0|37.297N|116.307W|0|5.4|SOUTHERN NEVADA. "KEARSARGE"
008|08/26/88|215323.1|38.810N|118.069W|20||Near Lovelock, NV
009|08/27/88|012517.7|11.303N|141.455E|33|5.2|WEST CAROLINE ISLANDS
215|08 27 88|020530.6|39.530N|118.470W|13|2.4|Nevada Local
010|08/27/88|163017.6|15.838S|172.144W|33|6.0|SAMOA ISLANDS REGION
216|08 30 88|023033.4|37.890N|116.081W|0.05|3.3|Nevada Local
011|08/30/88|122824.9|37.540N|118.353W|5||CALIFORNIA-NEVADA BORDER REGION.
012|08/30/88|180000.1|37.086N|116.069W|0|5.0|SOUTHERN NEVADA. "BULLFROG"
013|08/30/88|190345.0|37.086N|116.069W|0||BULLFROG COLLAPSE? OT/Location estimated
014|08/31/88|164516.0|31.789N|115.796W|5|4.9|BAJA CALIFORNIA. ML 5.1 (PAS).
015|09/01/88|165252.3|17.065N|99.265W|33|5.0|GUERRERO, MEXICO
016|09/02/88|102748.5|54.030N|161.491E|47|5.1|NEAR EAST COAST OF KAMCHATKA
017|09/05/88|061318.7|18.532N|70.391W|33|5.5|DOMINICAN REPUBLIC REGION.
018|09/07/88|115325.4|30.336N|137.364E|499|6.0|SOUTH OF HONSHU, JAPAN
718|09/07/88|115325.4|30.336N|137.364E|499|6.0|SOUTH OF HONSHU, JAPAN *** S-WAVE 
019|09/13/88|005845.9|29.806N|138.364E|447|5.8|SOUTH OF HONSHU, JAPAN
020|09/14/88|035957.4|49.801N|78.791E|0|6.1|EASTERN KAZAKH SSR
021|09/14/88|221407.6|23.387S|67.945W|124|5.8|CHILE-ARGENTINA BORDER REGION
022|09/15/88|184803.2|1.404S|77.896W|189|5.8|ECUADOR. 
722|09/15/88|184803.2|1.404S|77.896W|189|5.8|ECUADOR. *** S-wave 
023|09/16/88|000652.9|22.952S|175.413W|33|4.9|TONGA ISLANDS REGION
024|09/16/88|021614.9|20.362S|178.364W|500|5.2|FIJI ISLANDS REGION
025|09/16/88|024535.8|20.170S|177.770W|500|4.7|FIJI ISLANDS REGION
026|09/16/88|062729.0|17.785S|169.065E|33|4.9|VANUATU ISLANDS
027|09/17/88|062014.6|29.900N|114.100W|10|4.4|BAJA, CA from NEIC via phone
028|09/17/88|152353.7|44.910N|152.945E|43|5.3|KURIL ISLANDS REGION
029|09/19/88|025630.7|38.432N|118.320W|5|4.5|CALIFORNIA-NEVADA BORDER REGION.
030|09/19/88|032215.8|38.461N|118.341W|5||CALIFORNIA-NEVADA BORDER REGION.
032|09/19/88|185837.7|23.003S|175.508W|33|5.4|TONGA ISLANDS REGION
033|09/19/88|210145.8|38.478N|118.111W|5||CALIFORNIA-NEVADA BORDER REGION.
034|09/20/88|001609.1|38.937N|118.063W|5||CALIFORNIA-NEVADA BORDER REGION.
035|09/21/88|095851.8|46.129N|152.142E|38|5.9|KURIL ISLANDS
042|09/26/88|082321.4|35.402N|140.864E|45|5.9|NEAR E COAST OF HONSHU, JAPAN 
045|09/30/88|003014.8|41.535N|121.627W|5||NORTHERN CALIFORNIA. ML 4.1
046|09/30/88|004004.4|41.534N|121.598W|5||NORTHERN CALIFORNIA
047|09/30/88|214501.1|19.356S|177.555W|548|5.4|FIJI ISLANDS REGION
747|09/30/88|214501.1|19.356S|177.555W|548|5.4|FIJI ISLANDS REGION *** S-WAVE 
048|10/01/88|094324.5|35.305S|106.059W|10|5.6|EASTER ISLAND CORDILLERA
049|10/02/88|160930.0|27.100N|110.100W|10|4.7|GULF OF CALIFORNIA from NEIC via phone
050|10/03/88|004557.8|10.227S|161.243E|130|5.5|SOLOMON ISLANDS
051|10/04/88|003410.7|41.420N|121.593W|5||NORTHERN CALIFORNIA. ML 3.2
053|10/08/88|044624.4|18.693S|172.429W|33|6.7|TONGA ISLANDS REGION
753|10/08/88|044624.4|18.693S|172.429W|33|6.7|TONGA ISLANDS REGION *** S-WAVE 
054|10/08/88|211420.1|36.098N|117.860W|6||CALIFORNIA-NEVADA BORDER REGION.
055|10/08/88|212606.3|36.098N|117.860W|6||CALIFORNIA-NEVADA BORDER REGION.
058|10/10/88|071921.2|23.161S|171.969E|33|5.6|LOYALTY ISLANDS REGION
059|10/10/88|182030.0|28.344S|177.670W|57|6.5|KERMADEC ISLANDS REGION
759|10/10/88|182030.0|28.344S|177.670W|57|6.5|KERMADEC ISLANDS REGION *** S-WAVE 
060|10/11/88|133005.1|40.279N|125.632W|10|3.6|OFF COAST OF NORTHERN CALIFORNIA 
061|10/13/88|140000.0|37.089N|116.049W|0|5.9|SOUTHERN NEVADA. *** "DALHART" 
062|10/13/88|161807.8|37.089N|116.049W|0|4.3|SOUTHERN NEVADA. *** "DALHART COLLAPSE" 
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Figure Captions
.sp
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Figure 1.  Basemap of Nevada.  Heavy lines show the locations of the
1986 PASSCAL Basin and Range Active-Source Seismic Experiment.  The 
1988-89 Passive-Source Experiment was located in an area with a radius
of 20 km around the intersection of the 1986 lines.
.sp
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Figure 2.  Expanded map of stations locations.  Boxes are the stations
of the Large Aperture Array, diamonds are the stations of the Small
Aperture Array, and small triangles are the sites of the 1986 Active
Source Experiment.
.sp
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Figure 3.  P-wave trigger for Event 024 recorded by the Small
Aperture Array.
.sp
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Figure 4.  Trigger for Event 011, regional event from the  
California-Nevada border region, recorded by the Large Aperture Array.
Station d3, bottom trace, was known to have some timing problems.
.sp
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Figure 5.  Trigger for Event 215, a local Nevada event,
recorded by the Large Aperture Array.