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

Solar for Summer Only Enclosure

Summer Only Solar Panels

10W or 20W of solar power are usually sufficient for summer only experiment depending on a typical seismic station load.

EarthScope EPIC's Polar Group uses both the Suntech STP010 (10W) and the STP020 (20W).  They are both efficient, monocrystalline silicon solar panels and have strong frames.  A mount was designed in house and manufactured specifically for these panels to attached them directly to our  “summer only” enclosures.

Solar Equipment for Year Round Polar Programs

Low Power Solar Panel System

This solar panel system uses three Suntech STP020S  (20W) Monocrystalline Silicon solar panels mounted in a triangle to take advantage of the 24 hours a day solar insolation.   With the combination of cold temperature and solar reflection off the snow, this system produces close to 40W worth of solar power all day long in clear conditions.  This is more than adequate for most seismic recorder configurations.

This solar panel system is also very simple and quick to install in snow.  All that is needed is to have the base of the solar system buried in two feet or more of well compacted snow.  No guying is necessary.  Only one solar cable is needed to connect to a junction box located on the post.

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 EarthScope EPIC Polar Program.

Accelerometers

EPIC Accelerometers: Kinemetrics FBA-2 Episensor Features:

Strong-motion sensors are accelerometers, and are designed to measure the large amplitude, high-frequency seismic waves typical of large local earthquakes. These seismic waves result in the strong ground motion we feel during a large earthquake. Strong ground motion is often to blame for the structural damage that occurs during an earthquake. The data seismologists record with strong motion sensors is used to improve the design of earthquake resistant buildings and to understand earthquake-induced geologic hazards like liquefaction and landslides. The range of motions of interest for strong-motion applications includes accelerations from 0.001 to 2 g and frequencies from 0 to 100 Hz or more.

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Broadband Vault Construction

 

Download Diagram of Vault (jpg)

Construction of the vault for broadband seismometers has a direct impact on data quality. Before construction can begin there are two other important considerations as well; location, and setting. A short discussion of these topics precedes the construction details because you should really pick the right site before going to all the work of building a vault. It takes a long time to find good sites which balance the competing requirements of low noise, access, security, position within the array, power, permission, etc. Finding one site per day is fairly productive.

Cold-rated Guralp CMG-3T Sensor

The Cold-rated Guralp CMG-3T seismometer is described in detail in the Polar section article "Sensors for Year Round Polar Programs".

Equipment Certification

All equipment, especially dataloggers, 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.  EPIC makes every effort to ensure that all equipment are operating to the manufacturers specifications, and that all on-board consumables (such as betteries, etc) are fresh.

This article contains links to pages on procedures and metrics employed in the routine certification of:

Sensors Dataloggers
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Offloading Data

Data that is recorded locally, as opposed to telemetered must be offloaded and stored.  The actual procedures for offloading data depend on type of DAS and the type of media that the data is recorded on.  Offloading should be done as soon as possible after visiting the site in order to secure the data.  If possible offloading and data review should be done close enough to the site so that, if a problem is detected, the site can be revisited.

In general the offload procedure is as follows.

1. Verify that there is the expected amount of data on the media.  If there is not the expected amount of data there may be a problem at the site.

2.  Offload the data.

3.  Verify that the size of the offloaded data corresponds to the amount of data that was on the media.

4.  Review the data for indications of station problems and for data integrity.

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