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Here are some of the articles that have been recently posted to the PASSCAL website:

Three-component Node Procurement Update

As a response to the seismological community's desire to deploy a larger number of 3-component nodal seismic systems, the IRIS PASSCAL standing committee has guided IRIS management to procure more nodes for the PASSCAL pool. IRIS already has 73 Magseis Fairfield ZLAND 3-component 5Hz nodes in the pool and these have been subscribed for more than 2 years out. We have now begun the procurement of another 460 Magseis Fairfield nodes for general PASSCAL pool use. We expect to receive these new nodes in the fall of 2018. The new nodes should be ready for general pool usage starting in February, 2019 after evaluation and acceptance is complete (bringing the general node pool to 533 units). Please feel free to include the new nodes in instrument requests for experiments with start dates after February 2019.

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PQL II - Program for Viewing Data

April 21, 2009


PQL II is a program for viewing time-series data in any of four formats: MSEED, SEGY,  SAC, or AH (though, to be honest, PASSCAL staff has not used the AH option). It is the second generation PQL, hence the name PQL II. Both generations of code were written by Richard Boaz and PASSCAL staff supports the code on MAC OS X, LINUX, and Solaris platforms.To install PQL II on your system, you need to go the PASSCAL download page, or directly to PQL II download on PASSCAL's FTP area.

The HELP menus for PQL II are actually helpful. Use them a lot till you get to know the program.

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December 31 2016 Leap Second

Leap Second's effect on PASSCAL RT-130 and Q330



Data time starting at 2017:001:00:00:00 is +1 second from truth for 1-2 minutes (seen in controlled tests) until a clock correction, followed by a gap of 2-40 seconds per channel depending on sample rate.


Data time starting at 2017:001:00:00:00 is +1 second from truth for 15min - 9:42hrs (seen in controlled tests) until a clock correction. Some data (~6secs in tests) around the time correction is mistimed, sometimes 11 years in the future, or missing.

IRIS PASSCAL Data Policy Update

IRIS/PASSCAL has updated our Data Policy. The new Policy, which was published on November 1, 2017,  can be perused here. It details the archiving requirements for data collected with IRIS PASSCAL equipment through the PASSCAL Instrument Center (PIC)

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ref2sac fixes and enhancements

ref2sac incorrectly converts Ref Tek RT 130 data files to SAC. I found and fixed a number of bugs in the Mac OS X PASSOFT release of ref2sac. I added LAT, LON, and ELEV to the SAC files. I set the dependent variable type in the SAC file to UNKNOWN, since the data are in counts, not engineering units. I added an option to create the SAC output files in a single, flat directory structure, with unique file names. Those names include an .R. to identify that they contain raw counts.

Attached are my patched files and a README of the changes, plus several sample data files. (The sample data files should not be redistributed without permission.) The sample data files were converted to SAC using the following commands:

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Sensor Certification


All equipment, especially sensors and cables, are cleaned and comprehensively tested when they arrive at the PIC, regardless of whether the equipment are newly delivered from the manufacturer or being returned from an experiment.  PASSCAL makes every effort to ensure that all equipment are operating to the manufacturers specifications.

This article outlines the procedures undertaken and metrics employed by the PIC to verify that sensors operate within manufacturers specifications.


All sensors returning from a field experiment are subject to the following procedures:

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All files are in .png format with clear backgrounds.

PASSCAL (gradient gray) PASSCAL (legacy, gradient color)   PASSCAL (slide)  


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Grounding when Static is a Problem

Grounding of remotely-powered stations (not AC-powered), for stations where static charge is a problem.

This note concerns only those stations utilizing a remote autonomous power system and solar panels. Systems that will be using AC power should contact the PIC staff for more information on safely using these types of power sources.

Grounding of DAS units should only be attempted in extreme cases where static charge is a problem (for example, failing equipment such as external GPSes). Attempts to ground DAS units can lead to ground loops if not properly done, or even if done to best practices!  It should only be attempted when the sensor itself has been isolated from ground by a non-conducting plate such as a tile or phenolic pad.  Pads which are not part of the original vault design can also cause stability/noise problems, and must be well coupled to the base of the vault or concrete.

PASSCAL SEG-Y Trace Header

 PASSCAL SEG-Y utilizes big endian byte order and sets the various trace headers as outlined below.


PASSCAL SEG-Y Trace Header


Updated Instrument Response for Trillium_120, Trillium_240 (2 Generations) and Taurus

Instrument Response files released from Nanometrics for Trillium 120 and Trillium 240 sensors have been evaluated and updated for Antelope, where they are used to generate dataless and RESP files.