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.

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 EPIC:

Vault Equipment Drawings Vault Double wall UV resistant polyethylene shell 2" thick indexed phenolic sensor base 3" thick polystyrene insulation Trillium 240 or Guralp T3 seismometers Detailed Drawings 3" Thick Insulation 2" Thick Indexed Phenolic Base Double Wall UV Resistant Polyethylene Shell

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.