How Low-Cost Sensors Are Revolutionizing the Study of Earth's Most Dangerous Natural Phenomena

From Hollywood to Hard Science: The Evolution of Hazard Sensing

Thirty years ago, the blockbuster movie Twister dramatized a group of scientists risking their lives to chase tornadoes in the name of research. While the film’s portrayal included exaggerated sensationalism and special effects, it accurately depicted the concept of using distributed, low-cost sensors to study natural hazards. Today, this approach is known as "large-N" sensing—a method that deploys tens to hundreds of sensors across wide areas to collect critical data.

Advancements in Seismology and Infrasound Science

Large-N sensing has led to significant breakthroughs in seismology and infrasound science. These networks have enhanced our understanding of seismic ground motion and provided insights into volcanic eruption dynamics [e.g., Rosenblatt et al., 2022; Anderson et al., 2023]. The key advantages of these systems include:

• Robust spatial sampling: Capturing data from multiple locations simultaneously.
• Signal extraction from noise: Isolating weak signals amidst environmental interference.
• Detection of small signals: Identifying subtle changes in hazardous environments.
• Remote sensing capabilities: Monitoring natural hazards in inaccessible or dangerous locations.
• Redundancy for sensor protection: Safeguarding equipment from risks like lava flows, wildfires, severe weather, or even animal interference.

Boise State University’s Pioneering Research

Since 2013, researchers at Boise State University’s (BSU) Department of Geosciences have leveraged low-cost, large-N sensing technology to study infrasound from geophysical phenomena [e.g., Slad and Merchant, 2021]. Over the past decade, their work has produced scientific successes across diverse environments and continues to advance.

The Science Behind Infrasound Sensing

Infrasound refers to low-frequency sound waves below the threshold of human hearing (less than 20 Hertz). Violent natural processes such as landslides, volcanic eruptions, earthquakes, avalanches, and meteors generate infrasound. While these events may also produce audible sound, the subaudible band is often far more energetic in terms of sound intensity. Additionally, infrasound has long wavelengths that can travel long distances with minimal attenuation, making it ideal for remote sensing of natural phenomena.

The Birth of the Gem Infrasound Logger

The BSU research team sought to develop affordable infrasound sensing solutions after discovering the high cost of commercial data logging systems—the devices that record and store sensor data. These systems can be significantly more expensive than the infrasound transducers (sensors) themselves. The financial incentive to create a cost-effective alternative became urgent after the team lost critical instrumentation during the 3 March 2015 eruption of Chile’s Villarrica volcano. The eruption produced a 2-kilometer-tall lava fountain, burying the deployed hardware—including seismic and infrasonic sensors and their commercial multichannel data loggers—beneath lava [Johnson et al., 2018].

This loss spurred the development of the Gem infrasound logger, a customized, all-in-one sensor and data logger built using the Arduino open-source electronic prototyping platform. The Gem features a low-power microcontroller and offers a high dynamic range, capable of detecting sound pressures from millipascals to 100 pascals.

"The financial loss from the Villarrica eruption was a turning point. It pushed us to innovate and create a solution that matched the performance of commercial systems at a fraction of the cost."

Future Directions in Large-N Sensing

The BSU team’s decade-long effort demonstrates the transformative potential of large-N sensing in geoscience. By continuing to refine low-cost, high-performance sensor networks, researchers are unlocking new ways to monitor and understand Earth’s most hazardous environments. This innovation not only advances scientific knowledge but also enhances safety and preparedness for communities facing natural disasters.