Polar Programs

POLENET Project

The Polar Earth Observing Network (POLENET) is a large international, multidisciplinary project which is a core activity of the International Polar Year (IPY) 2007-2009.  The project combines Seismic and GPS instrumentation at remote sites in Antarctica.  The data collected during the POLENET experiment will enable new studies of the inner earth, tectonic plates, climate, and weather.  U.S. POLENET projects are supported by the National Science Foundation. PASSCAL supports the U.S. seismic portion of POLENET by providing specialized cold-hardened, equipment, field support, and training for University based field teams.

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:

Antarctica Shipping

The PASSCAL Instrument Center arranges shipping for equipment used by Antarctic experiments.  PASSCAL can also arrange for shipment of your equipment along with the PASSCAL equipment to the Antarctic. Please contact passcal [at] passcal [dot] nmt [dot] edu if you wish to have your equipment included with your PASSCAL equipment Antarctic shipment.

For further information on the United States Antarctic Program logistics and shipping, visit http://www.usap.gov/logistics/#IntercontinentalAirliftSchedule

Seismic Sensor Vaults

The type of seismic sensor vault and the amount of sophistication it requires, is dependent on the type of seismometer.  A geophone does not require a “vault” per se, it can be buried in dirt or snow and be kept reasonably level in the process. A sensitive broadband seismometer requires a quiet, temperature stable and level vault.  In the Antarctic two main styles of vaults are used for broadband seismometers:  the rock vault and the snow vault.

The Rock Vault

In rocky environments where digging is nearly impossible, a weatherproof enclosure with a rigid bottom, typically aluminium, is secured to the ground.  The seismometer is then set inside, oriented properly and leveled.

To reduce noise caused by wind, and to thermally stabilize the vault and protect the instrument from flying debris, a double walled dome is placed on top of the vault and anchored to the ground as well.

Cold Rated Guralp CMG-3T

The Guralp CMG-3T seismometer is a 3-axis broadband instrument that has a flat response to ground velocity between 120s and 100Hz.  It has been tested to operate down to -55C and only draws 0.3W of power.

PASSCAL's Polar program has purchased the cold-rated 3Ts (with active logic high) for broadband experiments in Antarctica.  When powered and locked, the reported mass positions will be '0'.  This does not mean that the instrument is dead or unpowered.  Once the 'unlock' command is initiated, first the lock/unlock and then the centering motors should run and finally result in meaningful mass position readouts.

The CMG-3T has a low tilt tolerance and is sensitive to temperature changes, it therefore requires a well established and well thermally isolated vault.

Quanterra Q330

To record seismic data during the extremely cold Polar nights, the IRIS PASSCAL Polar Group relies on the Quanterra Q330 digitizer due to its exceedingly low temperature tolerance.   The Q330 is a 24 bit, 3 or 6 channel digitizer. In addition to its very low temperature tolerance, its very low power consumption makes it ideal for year round experiments in the Antarctic deep field.

 

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.

Scenic Antarctic Photos