Multi Channel

On Friday, November 1st 2013, a group of students and teachers from Bethesda, Maryland's Lycée Rochambeau/ French International School visited the IRIS/PASSCAL facility on Socorro NM for some hands-on demonstrations of how seismic measurements are used to "see" geological strata underground.  The class, led by instructor Marc Roux, head of the Biology and Geology Department, were assisted by PASSCAL scientists Greg Chavez and Michael Johnson during the deployment of a long string of geophones and a multi-channel data acquisition system.  The students then used heavy hammers to produce active source tremors, and then were able to see the seismic responses in real time.  The class assembled in the PASSCAL conference room to hear PASSCAL scientists/data specialists Dr. Wallis Hutton and KatyLiz Anderson discuss how such measurements can be used to find the depth of subsurface structures like the Moho.  The visit was capped with a tour of the PASSCAL facility, led by scientist/software engineer Dave Thomas. (Photo: student Salomé Carcy; credit: Dr. Wallis Hutton)

Currently, the only controlled active source available from PASSCAL is the PEG 40Kg Propelled Energy Generator, manufactured by R.T. Clark Companies, Inc. PASSCAL has purchased its first fully automated PEG-40Kg system in 2011. The system is light weight, and highly portable, and is designed to easily mount onto a truck or SUV hitch. Seismic energy is produced when  a large hammer mass weight is propelled by an elastomer band (i.e. a very large rubber band) onto an impact plate, producing an impact frequency range of 10-250Hz. The source is controlled with a hand held motor controller,  and can operate in single cycle or continuous cycle mode. The device is powered by a 12V large capacity battery (car battery).  The PEG-40Kg was received, assembled, and field-tested by  PASSCAL staff on June 23rd-28th, 2011.

A datalogger (also know as data acquisition system or DAS) is piece of electronic equipment which converts an input into a digital time series representation. Immense care should be taken when setting up and programming a datalogger. It is highly recommended that only experienced users program their own dataloggers and all others should consult a PASSCAL staff member for assistance.

While specific procedures and programming details will vary between the various types of dataloggers, there are several things that hold true when working with any datalogger.

The datalogger should be:

GEODE 24-CHANNEL IN-FIELD SEISMOGRAPH.

System consists of one 24-channel Geodes, with two built-in high-speed connections to interface with other Geodes and a PC-compatible controller or the StrataVisor NZ seismograph.

Suitable for reflection, refraction, downhole, crosshole, surface wave, and tomography surveys, and seismic monitoring.

PASSCAL has been upgrading its pool of Multi-Channel Dataloggers in recent years to include multiple ES-3000 Geodes and a 60 Channel Strata View NZXP. These upgrades are also compatible with all of PASSCAL's Multi-Channel Cable System, which were originally purchased for use with the Geometrics StrataVisor NX. These  Units employ a new concept in portable exploration seismographs. They combine the ruggedness and high signal quality of a distributed system with the convenience and cost effectiveness of personal computer-based control devices. See Geode and Stratavisor Dataloggers for more Details.