Summer Only

The Geophysical Earth Observatory for Ice-Covered Environments (GEOICE) project was a NSF collaborative Major Research Instrumentation (MRI) program that expanded the PASSCAL Polar group’s observational capabilities and logistical efficiencies. GEOICE developed a rapidly deployable, dense footprint seismic observatory system for operation in ice-covered areas. The GEOICE project was a collaborative effort between Central Washington University (CWU), Incorporated Research Institutions for Seismology (IRIS) and the Portable Array Seismic Studies of the Continental Lithosphere (PASSCAL) Instrument Center at the New Mexico Institute of Mining and Technology.

PASSCAL's strategy for designing cold-hardened seismic systems is driven by the need to maximize heat efficiency and minimize payload while maintaining continuous recording throughout the Polar winter. Our design is for a basic 2W autonomous system. Power is provided by a primary Lithium Thionyl Chloride battery pack and is backed by a secondary, solar charged AGM battery pack. Station enclosures are heavily insulated and rely on instrument generated heat to keep the dataloggers within operating specification. Although insulated, broadband sensors are operated close to ambient temperature.

This checklist is a list of items to consider while preparing for a new field project.  It is aimed at providing a list of things to think about while making preparations for and assessments of possible seismic sites. This checklist is also appropriate for the initial installations and for the removal of the equipment at the end of the project. These guidelines are fairly general but focused for polar regions.  It applies more to the Arctic and Sub-arctic regions rather than Antarctica, because for Antarctic projects, a lot of these issues are dealt with by the US Antarctic Program.

  

Site Assessment: Climatic conditions:Wind, snow, temperature, altitude, ... Access: On foot: conditions (all year, seasonal), roughness of terrain, safety, man power, ... By wheeled/tracked vehicle: conditions (all year, seasonal), roughness of terrain, ... By fixed wings aircraft: airstrip conditions (all year, seasonal), typical weather conditions,cost, availability, safety, permitting, ... By helicopter: landing zone conditions, typical weather conditions, cost, availability, safety, permitting, ... By boat:land base vs. ship base, ease of access to land, protection from storms, issues of accidental introductions of rats and other non-native species to protected islands, cost, availability, safety, ... Permitting (Public land, private land, restricted land, fees, monitored access, limited access to certain dates, etc). Type of ground: Rock, mud, snow, ice, vegetation, sand, gravel, etc. Hazards to the equipment: Wildlife: Bears (very destructive!), rodents, foxes, cows, etc. Humans: Theft, vandalism, etc. Hazards to crew personnel: Climatic conditions. Access (steepness of terrain, crevasses, isolation, volcanic area, etc). Wildlife (Bears, moose, etc). Humans (locals with guns, etc). Site Installation: Dates: Choice of dates to simplify logistics and installation. Take into account climatic conditions. Personnel, transport and equipment availability. Maximize data return. Minimize cost. Permitting: For land use. For access. For use of vehicle or aircrafts Transport: Personnel:customs issues, ... Equipment:customs issues, potential HazMat, ... Housing: Food: Contingencies:Things rarely all go as planned. Site Removal and Equipment Regrograde: Permitting:land reclamation requirements. Transport:Methods, customs issues, potential HazMat, scheduling. Returning equipment to PASSCAL Instrument Center:

For summer only deployments, either short-period seismometers and geophones or broadband seismometers are typically installed. In the case of short-period sensors or geophones, a “vault” is not required and the instrument is often buried in the snow at a shallow depth and reasonably leveled.  If broadband seismometers are used, a vault needs to be built to hold the instruments. This involves more work as the sensors have to be accurately oriented, leveled and protected from wind noise and thermal changes.  For a detailed description of broadband seismic vaults for polar environments, see the Specialized Polar Equipment section.

Your choice of seismic sensor for Polar research will depend on your scientific targets. PASSCAL has a wide range of both passive and active seismic sensors appropriate for controlled source, local or regional seismicity, ice dynamics or teleseismic studies. A comparison of our sensors can be found here.

Short Period Sensors

These are typically used for controlled source experiments, short term, local seismicity or ice studies.  The instruments available are the Sercel L-28 and L-22.  The L-28 is a 4.5Hz 3 component geophone while the L-22 is a 2Hz 3 component seismometer.

Refraction Technology RT-130

The Reftek RT-130 is a 24bit, low power, robust and very portable seismic data recorder.  It is well suited for deployment in harsh climate environment and is easy to program and retrieve data in the field.  It can have 3 or 6 channels and records data on Compact Flash (CF) cards.

Here are several documents regarding summer-only equipment for Polar Projects. Batteries DAS Power Sensors Solar Station Enclosure Vaults

The Polar Program of IRIS/PASSCAL is dedicated to supporting with seismological research in the Arctic and Antarctic.  As opposed to traditional seismic stations installations around the world, instrumenting the Arctic or Antarctic require special consideration due to the extreme nature of the climatic conditions, temperature being the primary challenge.

Summer Only Solar Panels

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

IRIS PASSCAL'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.

For summer only deployments, special and costly, heavy insulation is not needed since the temperature at that time of the year remains high enough that the electronic equipment and batteries will continue to operate normally without a heat source.

The PASSCAL Polar Group's summer only enclosures are made of molded,  heavy-duty, lightweight polyethylene on the outside and have closed cell foam liner inside, cut to accommodate the equipment and batteries.  They were designed with portability in mind and their outside dimensions are 24 in x 21 in x 11 in.

To ease deployment, the case was designed to contain all the equipment necessary as long as the sensor is an L28 or smaller.  At the site, only the seismometer needs to be installed and the solar panel needs to be mounted on top of the case.