Seismic precursors to the Whakaari 2019 phreatic eruption are transferable to other eruptions and volcanoes

Abstract

Volcanic eruptions that occur without warning can be deadly in touristic and populated areas. Even with real-time geophysical monitoring, forecasting sudden eruptions is difficult, because their precursors are hard to recognize and can vary between volcanoes. Here, we describe a general seismic precursor signal for gas-driven eruptions, identified through correlation analysis of 18 well-recorded eruptions in New Zealand, Alaska, and Kamchatka. The precursor manifests in the displacement seismic amplitude ratio between medium (4.5–8 Hz) and high (8–16 Hz) frequency tremor bands, exhibiting a characteristic rise in the days prior to eruptions. We interpret this as formation of a hydrothermal seal that enables rapid pressurization of shallow groundwater. Applying this model to the 2019 eruption at Whakaari (New Zealand), we describe pressurization of the system in the week before the eruption, and cascading seal failure in the 16 h prior to the explosion. Real-time monitoring for this precursor may improve short-term eruption warning systems at certain volcanoes.

Association Between Injection and Microseismicity in Geothermal Fields With Multiple Wells: Data‐Driven Modeling of Rotokawa, New Zealand, and Húsmúli, Iceland

“…The time series feature engineering techniques used in this paper were initially developed for anomaly detection in industrial steel casting (Christ et al., 2016). They have since been used to study seismic tremor in subduction zones (Rouet‐Leduc et al., 2018) and volcanic tremor prior to eruptions (Ardid et al., 2022; Dempsey et al., 2020). Here, we are exploring whether they may be useful in an induced microseismicity setting.…”

Phreatic and Hydrothermal Eruptions: From Overlooked to Looking Over

“…Teleseismic waves from the M6.7 earthquake in Chile in 2014 triggered seismicity and a small phreatic eruption in the Tatun volcano group of Taiwan ~ 200 s afterwards (Lin 2017). A M5.9 earthquake located ~ 10 km NE of Whakaari/White Island occurred on November 24, 2019, about three weeks prior to the deadly eruption on December 19 (Ardid et al 2022).…”

“…Such signals may reflect periods of pressurisation. At Whakaari/ White Island, some of the phreatic and hydrothermal eruptions were preceded by tremor episodes during which seismic amplitude increased from 2 to 5 Hz (Chardot et al 2015;Dempsey et al 2020;Ardid et al 2022). Seismic velocities and attenuation can also change preceding the eruptions (Mordret et al 2010;Saade et al 2019;Yates et al 2019).…”

Automated Eruption Forecasting at Frequently Active Volcanoes Using Bayesian Networks Learned From Monitoring Data and Expert Elicitation: Application to Mt Ruapehu, Aotearoa, New Zealand

“…The model also had 58 false positive alerts for the period with 5 eruptions, highlighting the need for care if using such methods for automated alerting and warning. In a follow-up study, Ardid et al (2022) describe a seismic precursor signal for gas-driven eruption derived through correlation analysis of 18 well-recorded eruptions in New Zealand, Alaska and Kamchatka. They related the signal to formation of a hydrothermal seal that enables rapid pressurisation.…”

“…This results in a build-up of pressure in the conduit below the seal and can led to eruption when that seal fails, e.g. Raoul Island and White Island (Ardid et al, 2022). Sealing also results in decreased gas flux, as observed in the lead up to the 2007 eruption, as well as a change in lake chemistry as cations that make up alunite/natroalunite seals (e.g., K and to a lesser extent Na) are depleted from the crater lake solution (Christenson et al, 2010).…”