NWT RESEARCH DATABASE

Regions: Inuvialuit Settlement Region, Gwich'in Settlement Area

Tags: physical sciences, geology, seismology, tectonic movement

Objective(s): To deploy ground motion sensors (~270 total) throughout Alaska and western Canada.

Project Description: This project consists of a large deployment of ground motion sensors (~270 total) throughout Alaska and western Canada; 28 located in Yukon Territory and 5 in the Northwest Territory. Each station senses the ground movement from distant earthquakes and sends data via satellite or radio modem to a central receiving point in San Diego. The purpose of collecting these data is to study deep geologic structure of the earth, dynamics of tectonic motion, earthquake hazard, as well as induced seismicity related to human activity (disposal wells and carbon sequestration). This project images the deep structure of the earth, from depths of about 5km to the core of the earth but is primarily tuned to study the structure of the mantle (50-600 km beneath the surface) and to study plate tectonics and processes that create mountains. The instruments are spread too far apart (85km) to provide detailed imaging commonly used for exploration for oil and gas (whose drills go less than 4km deep) - though the technique applied is similar. One of the main objectives of the project is to improve the understanding of the active tectonics and geologic history of the North American continent. The Transportable Array (TA) will create images of the deep structure of the earth, from depths of about 5 km to the core of the earth. The instruments are spread too far apart to provide detailed imaging commonly used for exploration for oil and gas (whose drills go less than 4 km deep). The seismometers record earthquakes that occur locally, regionally, and throughout the world. The unique value of data produced from this array is due to the large area covered, and to the dense, regular spacing of hundreds of high-quality seismometers. Data from these stations are open and freely available and distributed to hundreds of researchers worldwide. The data help scientists gain new insights into earthquake processes and source characteristics, expand the understanding of earthquakes and lower crustal processes, and improve earthquake and tsunami warning systems for hazard mitigation. The general design and construction of the TA stations will be uniform for all site locations across the state. Slight variations may be required for individual sites based on local and environmental conditions. The typical Transportable Array station will occupy a footprint not to exceed 20 x 20 feet (6 x 6 meters), with a low physical profile. The equipment does not produce any noise or motion. To protect the sensor and reduce interference from surface noise, the seismometer will be placed in a PVC or steel cased hole 3 to 15 feet (1 to 5 meters) below the surface of the ground. The holes will either be augured or downhole hammered, and will be approximately 6 inches (15 cm) in diameter. Ground conditions at the site will dictate the hole depth and creation technique. At most TA stations, the electronics and power system will be housed in an above ground-insulated enclosure. The most common enclosure is a grey hut, measuring approximately 5’x5’x7’H (1.5x1.5x2H meters) and made of fiberglass that can be painted to blend in with the form, line, and color of the surrounding. Solar panels are mounted directly to the hut. The alternate station configuration consists of boxes/containers, which are secured to a frame, and anchored to the ground; this frame will also serve as the mount for the solar panel. Data is made publicly available through the Internet in real-time. Different displays of the data are geared towards public, education, and science users. Region specific outreach and teaching materials are available upon request, while more general resources are available at iris.edu. At the end of the project the research team will provide a summary of the work completed as well as significant findings from outside studies. Data is made publicly available through the Internet in real-time. Different displays of the data are geared towards public, education, and science users. Region specific outreach and teaching materials are available upon request, while more general resources are available at iris.edu. The fieldwork for this study will be conducted from January 12, 2018 to December 31, 2018.