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

Station Servicing Common Failures

Murphy was Right!

There is a long litany of things that can go wrong during station servicing, including:

Station Installation Suggested Materials List

Introduction:

One of the worst things that can happen during a deployment, especially a highly remote deployment, is not having the correct tools or supplies.  The following is a minimum suggested list of things to take if you are constructing a station that will house EPIC equipment for more than a few weeks. This list is in addition to the construction materials that will be used to make vaults, enclosures and fences.  Usually this would pertain to passive-source, broadband (or midband) experiments that deploy equipment for 1-2 years and will be visited approximately every three months during that time in order to check the data and the condition of the station.  EPIC will advise if any other specialty tools are required.  Please adjust quantities to provide for all installation teams and number of stations.

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Station Service Procedure

Although EPIC station installations can vary according to the type of equipment being used, servicing is relatively straightforward and similar between station designs and equipment. 

Station servicing has 3 main goals:
• To retrieve waveform data recorded by the station since the previous service;
• To identify and rectify any problems with equipment or damage to the station;
• To refresh consumable items such as compact flash (CF) cards, batteries, etc.

A simple station with easy vehicular access should take around 20 man-minutes to service.

Solar Panels

EPIC has both 30 and 65 Watt solar panels available.

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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.

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".