The GEOICE project was a collaborative instrumentation development effort funded by NSF and undertaken by Central Washington University, New Mexico Tech, and the Incorporated Research Institutions for Seismology (IRIS). Born out of a desire to facilitate additional seismic exploration of polar regions, the GEOICE project developed a multi-modal pool of seismic equipment for deployments in harsh polar environments, with the signature capability of recording the seismic wavefield with minimal aliasing. The completed instrumentation set is available as a community resource which expands on the IRIS PASSCAL Polar instrument pool. A significant amount of effort was put into testing the new equipment pool by the staff at the IRIS PASSCAL Instrument Center. Over the past several years this included both testing at the facility, as well as field testing of sensors, data loggers, and power systems in Alaska and Antarctica. The final equipment pool consists of 10 posthole polar-rated broadbands, 55 compact posthole polar-rated broadbands, 65 next-generation polar-rated dataloggers, and 200 all-in-one nodal-style high-frequency seismometers. Through a combination of design and form-factor, this pool will expand on and improve the instrumentation needed to perform high-quality seismic investigations of Earth’s ice-covered regions with reduced logistics and power requirements, while enabling spatially dense observations over a very wide frequency range. This new instrumentation can be used to study a variety of phenomena in ice-covered regions, recording signals from the solid Earth, glacier movement, liquid water flow and other relevant signals. Thus, these instruments will be a key tool for making observations of the interaction of the solid Earth with the cryosphere and atmosphere to better understand how drivers such as climate change impacts these systems.

Over recent years, remote sensing of sea ice has advanced at a rapid pace. However, there are inherent limitations in the ability of existing space and airborne sensors to observe changes in the properties of near-shore sea ice, especially over short (hourly) time scales. This information is of critical importance to the livelihood of local communities and to meteorologists who depend on knowledge of near-shore ice conditions for weather prediction. The use of near-real-time data from coastal seismic arrays promises to advance coastal ice observations by measuring the amplitude of background seismic noise, known as microseism. The microseism signal is generated by interactions between oceanic waves, the ocean floor, and the shoreline. Previous studies have shown that along polar coastlines the microseism is modulated by the presence of sea ice. In this feasibility study, we explore the use of power spectral density (PSD) measurements from the Utqiagvik station of the EarthScope Transportable Array (TA) to provide information about sea ice conditions off the northern coast of Alaska. PSD signals are compared with daily estimates of near-shore ice extent and concentration within the Beaufort and Chukchi seas. These are derived from satellite passive microwave radiometer data as well as visible and short-wave infrared imagery from the Moderate Resolution Imaging Spectroradiometer (MODIS) and Visible Infrared Imaging Radiometer Suite (VIIRS) instruments. The amplitude of microseism at a frequency near 1 Hz is statistically correlated with ice coverage to determine if microseismic signals from a coastal station can be used to reliably identify particular ice events, including the onset date of summer melt, fast-ice breakup and formation, and the development of near-shore flaw-leads and polynas. Data from the Utqiagvik TA station is compared with observations from other northern coastal stations to determine if sea ice related microseismic signals are consistent across a range of geological and topographical environments. The expansion of the EarthScope TA seismic network to the Arctic coastline since 2011 presents a developing approach to sea ice observation. In the future it may complement established remote sensing techniques to provide a more complete picture of coastal ice conditions as they evolve.

The motivation and objective of the EarthScope Transportable Array (TA) is to record earthquake signals and image the structure of the North American plate, however the observations collected by this National Science Foundation funded project have enabled unanticipated discoveries, innovative data analysis techniques, and ongoing investigations across many disciplines in the Earth and space sciences. The Transportable Array utilized a survey approach to collect data in which high-quality stations were systematically installed in a dense geospatial grid. From the very beginning of the deployment, this strategy allowed for data-driven discovery, such as using seismic data to map out extensive travel time curves for acoustic waves in the atmosphere (Hedlin et al., 2010). While the emplacement of the seismic sensors was kept uniform along with the core components for power and communications, the Transportable Array station design evolved over time to include additional barometric pressure and infrasound sensors and, eventually, meteorological sensors measuring external temperature, wind, and precipitation. As the array rolled across the Lower 48 and the TA became more recognized outside of seismology, collaborations were forged and strengthened with researchers in the infrasound and meteorological communities. Along with standard approaches using direct measurements, inventive techniques were used to apply environmental data for observing tectonic phenomena as well as applying seismic data for observing environmental phenomena. The value of integrated scientific infrastructure became even more apparent with the Transportable Array deployment in Alaska and western Canada, with autonomous and telemetered stations occupying sites within large swaths of previously unmonitored and inaccessible terrain. The majority of Alaska TA stations collect weather data and a subset also include a detached soil temperature probe. As a result, data collected by the Alaska Transportable Array have been used to observe throughout the ‘spheres: the lithosphere (earthquakes, volcanoes, landslides), the cryosphere (sea ice), the hydrosphere (precipitation, fire preparation), the atmosphere and biosphere (weather forecasting, storm systems, bolides), and even into the magnetosphere (space weather).

Geohazards, including earthquakes, volcanic eruptions, floods, and landslides, cause billions of dollars in U.S. economic losses, loss of life, injuries, and significant disruption to lives and livelihoods on an annual basis. The ability of the geoscience community to respond rapidly after a hazardous event or at the signs of precursors to these events, provides critical data to understand the physical processes responsible for these destructive events. The Seismological Facility for the Advancement of Geoscience (SAGE) is an NSF-funded facility operated by the Incorporated Research Institutions for Seismology (IRIS). As a part of the SAGE award, IRIS will implement an expanded capability to facilitate rapidly responding to geohazards with geophysical instrumentation. After several years of gathering community input, IRIS is ready to begin procurement of a new suite of instrumentation for rapidly responding to geohazard events. During the past year, staff at the IRIS/PASSCAL Instrument Center have conducted instrument testing and evaluation to inform the preferred mix of instrumentation for the new rapid response equipment pool—which is expected to include broadband and nodal seismometers, digitizers, and infrasound sensors. This effort has been guided by recommendations from a recent Rapid Response Community Whitepaper, with ongoing oversight from the PASSCAL Standing Committee. A copy of the whitepaper, as well as recordings and presentations from hosted gatherings have been posted to IRIS’ Rapid Response to Geohazards webpage (www.iris.edu/rapid). With testing and evaluation complete, IRIS is looking ahead to procuring instruments and associated equipment over the next year, followed by acceptance testing and integration at the IRIS/PASSCAL Instrument Center. Concurrently, IRIS is working with community governance to formalize new policies and procedures that will outline how this new community resource can most effectively and efficiently be used for geohazard-related observations. Beginning in 2023, PIs will be able to schedule and use this equipment from the IRIS/PASSCAL Instrument Center. We look forward to presenting further details on the above-mentioned activities during the AGU Fall Meeting.

Over the past third of a century the Incorporated Research Institutions for Seismology (IRIS) has facilitated observational seismology in many ways. At the beginning of IRIS in 1984, and with the support of the National Science Foundation and in partnership with the US Geological Survey, IRIS embarked on deploying the Global Seismographic Network (GSN). Key characteristics of the GSN are its use of high-performance digitizers, very broad band seismometers, strong motion accelerometers, and high frequency sensors to provide multi-decadal observations across a wide frequency band and dynamic range. The IRIS Portable Array Seismic Studies of the Continental Lithosphere (PASSCAL) program has also operated since 1984. PASSCAL’s extensive inventory of seismic equipment has been used by scientists to make observations on every part of the globe. The number and breadth of observations made with this equipment has fueled thousands of research papers and contributed to the education of hundreds, if not thousands, of students. More recently, the IRIS-operated EarthScope Transportable Array (TA) provided a breakthrough in the systematic collection of data using an array of unprecedented size. The success of the TA has ushered in a new era of “Large N” seismology, focused on dense spatial coverage of sensors to reduce aliasing and provide more complete recording of the full wavefield. The TA highlighted the power of survey mode data collection, where systematic, spatially-dense, and high-quality data fuel data-driven discovery, as opposed to deployments made to test a specific hypothesis. Key future directions in observational seismology include an increasing emphasis on wavefield measurements. Deploying instruments in large numbers requires reductions in the size, weight, and power of units, as well as a focus on dirt-to-desktop data management strategies that merge data and metadata while minimizing human intervention with the data flow from the sensor in the dirt to the scientist’s desktop. Other critical frontiers include pervasive seafloor observations to enable studies of key structures like subduction zones, more accessible satellite telemetry to enable ubiquitous sensing of the environment, and new sensing technologies such as MEMS and Distributed Acoustic Sensing.