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

Sercel L-28-3D High Frequency Sensor

  Salient Features:  This 3-channel sensor has a frequency of 4.5Hz, is critically damped at .707 and has a sensitivity of 30.4 V/m/s.  Used for (but not limited to) active source (land and off-shore excitations), glacial movements, local earthquake and aftershock studies. Manufacturer Documents

Download the Brochure to obtain information about the L-28 geophones.

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40Hz High Frequency Sensor

Salient Features:

PASSCAL owns two types of 40Hz vertical geophones.

The 40Hz geophones for the Multichannel Digitizer Systems are manufactured by Sercel and Geospace.  These vertical geophones are critically damped at 0.555 and have a sensitivity of about 21 V/m/s. The 40Hz geophones for the Texan Digitizers these geophones are manufactured by Sercel.  These vertical geophones are critically damped at 0.555 and have a sensitivity of 35.3 V/m/s

Uses primarily include active source studies.

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Array of Arrays: Elusive ETS in the Cascadia Subduction Zone

ETS, or 'episodic tremor and slip', is a recently discovered phenomenon in seismic research. Similar to earthquakes but much smaller in magnitude, ETS events are associated with the subduction zone of some convergent plate boundaries. One such region, the Cascadia subduction zone under the Puget Sound, is the focus of an experiment by Ken Creager's group at the University of Washington (UW), called Array of Arrays.


  How long will it take? Training at the PASSCAL Instrument Center takes an average of 2 days to cover a typical experiment.    The first day involves an overview from the PI, a discussion of proposed logistics, introduction or review of project instrumentation and a practice site installation.  The second day covers station servicing and demobilization, the PASSCAL suite of software for data download and review, and introduction or review of PASSCAL preferred database and data archiving procedures. What can you expect from us?  Training on the hardware that PASSCAL Instrument Center will provide for your experiment.  This will include the Digitizer, Sensor(s), Handheld controllers, and Power Systems.
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August/September 2009 New Mexico Earthquake Swarm in the Central Rio Grande Rift

Courtesy Jana Pursley, NMT

Seismicity in central New Mexico, southwestern United States, is dominated by earthquakes occurring above the mid-crustal Socorro Magma Body (SMB). The SMB is a sill-like feature ≥ 3400 km2 in area, with a top surface at 19-km depth spanning the inner Rio Grande rift half-graben system. Inflation of the magma body at rates of several mm/year, perhaps coupled with shallow transport of aqueous fluids, is the prevailing model for the region’s long-standing and anomalous seismicity. Clustered swarms of small magnitude earthquakes have been noted since the 1860s throughout this region, and have been recorded instrumentally since the early 1960’s (Figure 1, blue squares, Sanford et al., 20021).

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Batholiths Onland 2009 Photo Recap

In July 2009, several IRIS/PASSCAL scientists assisted with the Batholiths Onland project. This large group effort involved over 50 scientists and grad students, for the purpose of making "a seismic refraction and wide-angle reflection survey across the Coast Mountains batholith of British Columbia, Canada."

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Workshop Agenda

PASSCAL Data Archiving Workshop San Francisco, California Gallery Room, Palomar Hotel December 13, 2009 Preliminary Agenda Agenda contents and schedule subject to change. updated 9/18/09

Morning Session: Passive-Source Processing and Data Archiving

Nanometrics Trillium 240 Polar Sensor

Nanometrics Trillium 240

The Nanometrics Trillium 240 is a symmetric triaxial broadband instrument that has a flat response to ground velocity between 240s and 200Hz, and has a low self-noise, below the New Low Noise Model between 100s and 10Hz.  The manufacturer specifications of operating temperatures are between -20C and +50C, but the Trillium 240 has operated reliably for us to temperatures below -60C.  The power consumption at low seismic noise conditions and with the instrument well leveled is about 650mW.  The Trillium has a +/-1deg tilt tolerance, is fairly sensitive to varying temperature, but was designed to be insensitive to atmospheric variations.

The Trillium 240 is well suited for medium to long term experiments in the Arctic and Antarctic supported by the IRIS PASSCAL Polar Program.