Quantitative Assessment of Remote Volcanic Eruption Detectability Using the Korea Infrasound Network

Infrasound has been widely applied to the remote monitoring of explosive volcanic eruptions. Although no active volcanoes are currently present within South Korea, explosive activity in neighboring regions can still generate transboundary hazards that require effective remote monitoring. In this context, we present a quantitative assessment of volcanic eruption detectability using the Korea Infrasound Network (KIN).

The KIN has been operated for more than two decades and was originally established to monitor local and regional acoustic sources and to discriminate between natural and anthropogenic signals. The network consists of Chaparral M2 infrasound sensors, each of which has a flat response from 0.1 to 200 Hz. Since 2011, eight infrasound arrays with apertures ranging from 0.15 to 1.68 km have been fully operational. We evaluate the detectability of eruptions with VEI ≥ 3 that have occurred since 2011, examining detection characteristics as a function of distance, azimuth, and atmospheric propagation conditions. Detection was performed using the Progressive Multi-Channel Correlation (PMCC) algorithm to identify coherent infrasound signals.

Many eruption signals recorded by the KIN extend into frequencies below the nominal flat-response bandwidth and are often obscured by persistent microbarom noise. Despite these limitations, volcanic eruptions were conditionally detected depending on eruption size and atmospheric propagation conditions. The analyzed cases include the 2022 Hunga Tonga–Hunga Haʻapai eruption (VEI 5), the 2020 Taal and 2021 Fukutoku-Oka-no-Ba eruptions (VEI 4), and several VEI 3 eruptions such as Asosan, Kirishimayama, and Raikoke.

Our results indicate that automated eruption detection using KIN is feasible, particularly at the TJIAR array in central South Korea. A long-term PMCC detection catalog spanning approximately 15 years (since 2011) was compiled for TJIAR and compared with independent eruption records from the Tokyo Volcano Ash Advisory Center and the Global Volcanism Program to assess detection reliability. This study represents the first long-term assessment of volcanic infrasound detectability based on the KIN. In addition, low-frequency infrasound sensors (MB3d) with an extended dynamic range were collocated at one of the KIN arrays in 2025 to improve low-frequency detectability. Ongoing work focuses on assessing improvements in eruption detectability through comparisons between legacy and upgraded sensor configurations, with implications for the development of an infrasound-based automated eruption detection and long-term monitoring of explosive volcanic eruptions in East Asia.