Scientists are launching a new project to study an underwater fault system that triggered a massive tsunami 80 years ago, affecting Hawaii, Alaska, Washington, and Oregon. The event was caused by a relatively small earthquake off the coast of Alaska, but its exact mechanism remains unclear. A team from Michigan State University (MSU) is preparing an expedition to measure the vibrations of tectonic plates in the Alaskan–Aleutian subduction zone, a region where one tectonic plate slides beneath another. The team will place waterproof sensors called seismometers on the ocean floor near Alaska. These sensors will be powered by batteries for 15 months and will use atomic clocks to precisely time the vibrations they record. The data will be retrieved later for analysis. This project is supported by a National Science Foundation grant and marks the first of its kind since January 2025, with MSU collaborating with the University of Hawaii. The 1946 tsunami was unusual because it was generated by a relatively small earthquake, and scientists still don't fully understand how it happened. While the new sensors won't reveal what occurred 80 years ago, they can provide insights into how the fault system is behaving today. This information can help assess the risk of future earthquakes or tsunamis in the region. Songqiao "Shawn" Wei, an associate professor at MSU, explained that while predicting earthquakes remains a challenge, understanding this area will improve the U.S. Geological Survey's risk maps, which in turn can influence building codes and safety measures. Earthquakes occur when tectonic plates, which make up the Earth's outer layer, get stuck and build up pressure until they suddenly slip, releasing energy that causes shaking. Scientists use this energy to study the Earth's interior, but collecting such data is difficult because it requires being in the right place at the right time. Wei places seismometers in known earthquake-prone areas, like Alaska and the Marianas, and leaves them for months or even years. Over time, the sensors record all the vibrations, which Wei later analyzes. However, studying underwater faults is more complicated than studying those on land, where solar panels and GPS can be used to power and track instruments. To study underwater faults, Wei's team must carefully map the ocean floor before deploying the seismometers, looking for smooth, flat areas to avoid damaging the sensors. Once deployed, a flotation system ensures the sensors descend slowly to the ocean floor. Deploying a single sensor can take hours. Understanding these risks is crucial because undersea earthquakes can displace water, creating tsunamis that grow as they reach shallow coastal waters. By studying how the Pacific and North American plates interact today, Wei's team hopes to better assess future earthquake risks. Wei is also interested in a phenomenon called slow earthquakes, where fault movement occurs over days or weeks instead of seconds, releasing energy without violent shaking. He is investigating whether slow earthquakes are connected to the 1946 event and why they seem to occur only in this part of the Aleutian subduction zone. The seismic data collected will allow him to "see" beneath the seafloor, similar to how a CAT scan reveals the inside of the human body. He is particularly interested in water trapped deep within the Earth and how it might affect the friction between tectonic plates, potentially influencing whether an earthquake stops or grows larger. Wei's team plans to launch their next research cruise in 2028, with the instruments left on the ocean floor for about 15 months. The data collected could help answer fundamental questions in earthquake science, and as Wei notes, "Earth is always way more complicated than our human labs."