In January 2022, the Hunga Tonga-Hunga Ha’apai volcano erupted with record-breaking force, devastating the island, triggering evacuations, and resulting in fatalities. The sudden eruption left scientists searching for ways to better predict such events. Recently, researchers identified a seismic wave precursor—a subtle Rayleigh wave signal that traveled across Earth’s surface about 15 minutes before the eruption. This wave, detected by seismometers located over 466 miles away in Fiji and Futuna, was imperceptible to humans yet detectable by seismic equipment, providing a vital clue that an eruption was imminent. This seismic wave precursor offers new possibilities for enhancing volcanic early warning systems, potentially granting the critical minutes needed to prepare for eruptions.
Volcanologist Mie Ichihara of the University of Tokyo, a co-author of the study, emphasizes the importance of early warnings for disaster mitigation, especially for island volcanoes, which can generate deadly tsunamis. While traditional early warning systems exist for earthquakes, tsunamis, and other natural disasters, volcanic eruptions often lack detectable signs. The Hunga Tonga-Hunga Ha’apai eruption had no visible surface indicators, making the Rayleigh wave the only identifiable seismic wave precursor preceding the event. Typically used in earthquake detection to determine parameters like epicenter and magnitude, Rayleigh waves could potentially be repurposed to monitor volcanic activity, allowing for improved real-time alerts.
This eruption, which produced a plume reaching 36 miles into Earth’s mesosphere within 30 minutes, was the largest recorded plume in history, surpassing the 1991 Mount Pinatubo eruption. Unlike earthquakes, volcanic eruptions rarely produce surface-traveling waves without any accompanying surface disturbances. However, the 2022 Rayleigh wave was detected before any visible eruption activity, making it a unique seismic wave precursor for volcanic eruptions. According to the research team, this wave likely originated from a fracture in the oceanic crust near the caldera of the volcano. This fracture allowed magma and seawater to enter the magma chamber, causing the land above to collapse and setting off the eruption.
Based on these findings, the researchers suggest that seismic stations, even hundreds of miles from a volcano, could detect eruption indicators in advance. While this approach wasn’t previously considered feasible in real time, Ichihara and her colleagues now see potential for using distant seismic data to detect future eruptions. Such a method could be especially useful for underwater or remote island volcanoes, where direct monitoring is challenging. These findings represent a step toward more accurate early warning systems, which could provide essential minutes of notice for evacuations and safety measures in high-risk areas.
The significance of this research extends beyond volcanic eruptions. Recent advancements in disaster prediction, such as using magnetic fields to detect tsunamis, show that innovative approaches to data analysis can reveal previously unnoticed warning signs. The 2022 eruption underscores the value of continued research into seismic signals for predicting natural disasters. By improving our understanding of seismic wave precursors, scientists hope to enhance early warning systems, potentially saving lives and mitigating the impacts of future eruptions, particularly for vulnerable island communities. This study’s insights mark progress in the ongoing effort to prepare for the unpredictable nature of volcanic activity.