The first second of volcanic eruptions from the Erebus volcano lava lake, Antarctica—Energies, pressures, seismology, and infrasound

Abstract

[1] We describe a multiparameter experiment at Erebus volcano, Antarctica, employing Doppler radar, video, acoustic, and seismic observations to estimate the detailed energy budget of large (up to 40 m-diameter) bubble bursts from a persistent phonolite lava lake. These explosions are readily studied from the crater rim at ranges of less than 500 m and present an ideal opportunity to constrain the dynamics and mechanism of magmatic bubble bursts that can drive Strombolian and Hawaiian eruptions. We estimate the energy budget of the first second of a typical Erebus explosion as a function of time and energy type. We constrain gas pressures and forces using an analytic model for the expansion of a gas bubble above a conduit that incorporates conduit geometry and magma and gas parameters. The model, consistent with video and radar observations, invokes a spherical bulging surface with a base diameter equal to that of the lava lake. The model has no ad hoc free parameters, and geometrical calculations predict zenith height, velocity, and acceleration during shell expansion. During explosions, the energy contained in hot overpressured gas bubbles is freed and partitioned into other energy types, where by far the greatest nonthermal energy component is the kinetic and gravitational potential energy of the accelerated magma shell (> 10 9 J). Seismic source energy created by explosions is estimated from radar measurements and is consistent with source energy determined from seismic observations. For the generation of the infrasonic signal, a dual mechanism incorporating a terminally disrupted slug is proposed, which clarifies previous models and provides good fits to observed infrasonic pressures. A new and straightforward method is presented for determining gas volumes from slug explosions at volcanoes from remote infrasound recordings.

Application of the Monopole Source to Quantify Explosive Flux during Vulcanian Explosions at Sakurajima Volcano (Japan)

“…Although most volcanic vents possess length scales of tens of meters to hundreds of meters the compact volcano source designation is reasonable for many strombolian or small vulcanian eruptions where principal acoustic radiation possesses wavelengths of hundreds of meters (Fee and Matoza, 2013). For example, Johnson et al (2004), Johnson et al (2008), and Gerst et al (2013) used the monopole source to quantify explosive gas emissions at Mount Erebus (Antarctica). They inferred gas burst outfluxes from the 40 m diameter lake on the order of 10 3 m 3 during ∼1 s eruptions.…”

“…We modify the double integration method used at Mount Erebus (e.g., Johnson et al, 2004;Gerst et al, 2013), and apply it to the considerably larger Sakurajima vulcanian explosions (see examples in Fig. 1).…”

Mass eruption rates in pulsating eruptions estimated from video analysis of the gas thrust-buoyancy transition—a case study of the 2010 eruption of Eyjafjallajökull, Iceland

“…Real-time monitoring systems based on Doppler radar (e.g., Vöge and Hort 2009;Gerst et al 2013), optical (e.g., Taddeucci et al 2012;Valade et al 2014), infrasound (see e.g., Johnson and Ripepe 2011;Ripepe et al 2013), and electrical methods (Büttner et al 2000) provide information that would allow near real-time estimates of the mass eruption rate. Existing methods, however, are affected by considerable uncertainties, with large variations between different estimates for the same eruption (for Eyjafjallajökull, see e.g., Woodhouse et al 2013;Ripepe et al 2013, Bursik et al 2012Gudmundsson et al 2012).…”

Autonomous thermal camera system for monitoring the active lava lake at Erebus volcano, Antarctica

“…5). Although detailed studies have been made of these events using other techniques (Gerst et al, 2013;Jones et al, 2008), little has yet been learned of how they influence the pulsatory behaviour of the lake. Previous thermal camera systems on Erebus did not record the majority of the bubble events since their capture rate was too slow.…”