Geology Reports⌕ Search
Home/Archive/USGS

USGS · 70198343

Shallow degassing events as a trigger for very-long-period seismicity at Kilauea Volcano, Hawaii

Matthew R. Patrick·David C. Wilson·David Fee·Tim R. Orr·Don Swanson
View original source ↗Export metadata ↓

Also available from

Abstract

The first eruptive activity at Kīlauea Volcano’s summit in 25 years began in March 2008 with the opening of a 35-m-wide vent in Halema‘uma‘u crater. The new activity has produced prominent very-long-period (VLP) signals corresponding with two new behaviors: episodic tremor bursts and small explosive events, both of which represent degassing events from the top of the lava column. Previous work has shown that VLP seismicity has long been present at Kīlauea’s summit, and is sourced approximately 1 km below Halema‘uma‘u. By integrating video observations, infrasound and seismic data, we show that the onset of the large VLP signals occurs within several seconds of the onset of the degassing events. This timing indicates that the VLP is caused by forces—sourced at or very near the lava free surface due to degassing—transmitted down the magma column and coupling to the surrounding rock at 1 km depth.

Explore related subjects

Bulletin of VolcanologyArticle

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Matthew R. Patrick, David C. Wilson, David Fee, Tim R. Orr, Don Swanson. 2011-05-12. Shallow degassing events as a trigger for very-long-period seismicity at Kilauea Volcano, Hawaii. https://doi.org/10.1007/s00445-011-0475-y

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related USGS reports

USGS2026

Examples of eruption response teams from the Alaska Volcano Observatory

During times of eruption response, volcano observatories need to organize themselves differently than during normal operations. The number of formal operational roles grows to ensure that critical responsibilities are covered, including management of all activities at the observatory as well as increased staffing to ensure proper surveillance of data and issuance of timely notices and warnings. The scope and approach differ for each observatory and, in fact, for different eruptions. The Alaska Volcano Observatory (AVO) maintains an extensive monitoring program and issues forecasts and warnings about volcanic eruptions and unrest in Alaska. Since 2000, AVO has used formal roles to perform these duties and has implemented a variety of team approaches to respond to larger eruptions. For the Augustine (2006) and Redoubt (2009) eruptions, management scaled from 3 up to ~ 8 people in a command team to cover all aspects of the response. During these and other eruptions (e.g., Okmok, 2008), an operations room was staffed continuously to cover real-time responsibilities pertaining to monitoring and issuing alerts while the command team focused on overall management. More recently, such as for Bogoslof in 2016–2017 and Shishaldin in 2019 and 2023, AVO used a virtual real-time response team to handle warning tasks and variations of an Observatory Volcanic Event Response Team (OVERT; Moran et al. 2024) to manage overall observatory response activities. In 2025, AVO employed a formal OVERT for the first time to oversee its response to unrest at Mount Spurr. Frequent implementation, nimble scaling, constant evaluation, flexibility, and good communication make the team approach effective. We present examples of several response teams used over the last 25 years, and lessons learned from them, in the hope that these will be helpful to other observatories facing crisis responses. These examples may also allow stakeholders and the public to better understand how observatories work.

Alaska↗
USGS2026

Timescales of cumulate mobilization and mixing for the 1868 A.D. eruption of Mauna Loa, Island of Hawai‘i

The deadly 1868 A.D. eruption of Mauna Loa’s lower Southwest Rift Zone (Island of Hawai‘i) included a M7.9 earthquake and associated tsunami and landslides, demonstrating the severe hazards posed by Earth’s largest active subaerial volcano. To better understand the relationship between intense seismic activity, dike emplacement, magma storage, transport histories, and mobilization of olivine cumulates at Mauna Loa, we examine compositional zoning of olivine in the 1868 lava flows. Samples range from basalt (< 10% olivine) to picrite (30–40% olivine). The olivine cargo is heterogeneous (Fo 78.2–89.2 ; forsterite = [Mg/(Mg + Fe) × 100]) but dominated by ~ Fo 89 cores that lie above the Fe-Mg equilibrium field of host glasses. Crystal rims < Fo 80 are due to post-eruptive modification in slow cooling lava flows. Minor element compositions fall within the range of other Mauna Loa olivine erupted in the past 200 years. Olivine crystals exhibit both normal and complex Fo zoning patterns that yield timescales of diffusive re-equilibration that range from 3 to 258 days, with 72% of crystals recording 71 days or less. These timescales correspond to magmatic priming of the summit reservoir system ~ 2 months prior to the eruption and the M7.9 earthquake likely facilitated the transport of the crystal-rich summit-derived magmas downrift shortly prior to eruption. If the recently proposed faster Fe-Mg diffusion coefficient is used, timescales instead range from < 1 day to 25 days, with most recording 1 week or less. In this scenario, most of the olivine zoning would have to have been generated after the M7.9 earthquake perturbed the system.

Hawaii↗
USGS2026

Geochemistry of the 2022 Mauna Loa eruption: A comparison with earlier historical summit reservoir eruptions, with implications for magma supply and recharge

On November 28th, 2022, following a record historical repose period of 38 years, Mauna Loa erupted about 145 × 10 6 m 3 of lava and tephra over a 15-day period. The eruption was confined to the summit caldera region and the upper Northeast Rift Zone and is remarkably homogeneous in composition in both time and space. In these respects, it is typical of prior shallow summit reservoir magma bodies, recently estimated to be at a depth of around 1–2 km beneath the caldera. In contrast with these earlier magma bodies, which typically contain 6.7–7.1% MgO and are perched at the low-MgO end of olivine-control trends, the 2022 lava and tephra are more evolved with 6.24 + / − 0.03% MgO. This implies a temperature difference of around 11 °C with the prior 1984 magma. The simplest explanation is that over 38 years, cooling and crystallization of the remaining 1984 magma body has significantly exceeded magma recharge, giving rise to the evolved 2022 magma. The problem with this model is that we know from a variety of geophysical observations that in those 38 years, Mauna Loa has been erratically inflating, with heightened periods since around 2000 attributed to magma recharge. To reconcile these differences, we suggest instead that the 1984 magma cooled and crystallized much more extensively, from 1166 °C to around 1106 °C, co-crystallizing plagioclase, clinopyroxene, pigeonite and subsequently enstatite instead of pigeonite. At this point, the residual 1984 magma would have an MgO content around 4.2% and been about 50% solidified. Subsequent recharge and mixing by dominantly reservoir magmas, derived from a deeper 3–4-km intermediate magma reservoir, eventually produced the 2022 magma.

Hawaii↗