Three-dimensional volcano-acoustic source localization at Karymsky Volcano, Kamchatka, Russia

Abstract

We test two methods of 3-D acoustic source localization on volcanic explosions and small-scale jetting events at Karymsky Volcano, Kamchatka, Russia. Recent infrasound studies have provided evidence that volcanic jets produce low-frequency aerodynamic sound (jet noise) similar to that from man-made jet engines. Man-made jets are known to produce sound through turbulence along the jet axis, but discrimination of sources along the axis of a volcanic jet requires a network of sufficient topographic relief to attain resolution in the vertical dimension. At Karymsky Volcano, the topography of an eroded edifice adjacent to the active cone provided a platform for the atypical deployment of five infrasound sensors with intra-network relief of ~600 m in July 2012. A novel 3-D inverse localization method, srcLoc, is tested and compared against a more common grid-search semblance technique. Simulations using synthetic signals indicate that srcLoc is capable of determining vertical source locations for this network configuration to within ±150 m or better. However, srcLoc locations for explosions and jetting at Karymsky Volcano show a persistent overestimation of source elevation and underestimation of sound speed by an average of ~330 m and 25 m/s, respectively. The semblance method is able to produce more realistic source locations by fixing the sound speed to expected values of 335-340 m/s. The consistency of location errors for both explosions and jetting activity over a wide range of wind and temperature conditions points to the influence of topography. Explosion waveforms exhibit amplitude relationships and waveform distortion strikingly similar to those theorized by modeling studies of wave diffraction around the crater rim. We suggest delay of signals and apparent elevated source locations are due to altered raypaths and/or crater diffraction effects. Our results suggest the influence of topography in the vent region must be accounted for when attempting 3-D volcano acoustic source localization. Though the data presented here are insufficient to resolve noise sources for these jets, which are much smaller in scale than those of previous volcanic jet noise studies, similar techniques may be successfully applied to large volcanic jets in the future.

Seismic Envelope‐Based Detection and Location of Ground‐Coupled Airwaves from Volcanoes in Alaska

“…† For example Johnson and Dudgeon (1992). ‡ Szuberla et al (2009) and Rowell et al (2014). § Zhang et al (2010) and Haney (2010).…”

Capturing the Acoustic Radiation Pattern of Strombolian Eruptions using Infrasound Sensors Aboard a Tethered Aerostat, Yasur Volcano, Vanuatu

“…Eruption directivity, where the energy and mass may be preferentially discharged from the conduit, has important hazardous consequences prompting public interest and research. Several examples of such directivity effects have been documented from visual (Lube et al, ), seismic (Kanamori & Given, ), infrasound (Jolly et al, ; McKee et al, ; Rowell et al, ), and GPS observations (Fournier & Jolly, ). Observed features of infrasonic records include seismoacoustic energy coupling and wave conversion (e.g., Johnson & Aster ; Ichihara et al, ), excitations from secondary source features such as jet turbulence (e.g., Matoza et al, ; Rowell et al, ), or distorted frequencies that may be ascribed to Doppler effects (Jolly et al, ).…”

“…Several examples of such directivity effects have been documented from visual (Lube et al, ), seismic (Kanamori & Given, ), infrasound (Jolly et al, ; McKee et al, ; Rowell et al, ), and GPS observations (Fournier & Jolly, ). Observed features of infrasonic records include seismoacoustic energy coupling and wave conversion (e.g., Johnson & Aster ; Ichihara et al, ), excitations from secondary source features such as jet turbulence (e.g., Matoza et al, ; Rowell et al, ), or distorted frequencies that may be ascribed to Doppler effects (Jolly et al, ). Eruption directivity effects may be associated with hazardous surge events (Lube et al, ), ballistics impact on infrastructure (Fitzgerald et al, ; Tsunematsu et al ), and lateral blasts (Kanamori & Given, ; Kieffer, ); hence, the rapid recognition of such events from real‐time seismoacoustic systems may someday improve response capabilities for emergency managers.…”

Volcano Infrasound and the International Monitoring System

“…This allowed Kim and Lees (2014) to locate a series of ten typical explosions at Sakurajima within a tight cluster (<100 m radius) at the base of the active crater, consistent with thermal infrared source vent locations. In a similar manner, Rowell et al (2014) illustrate the difficulties in resolving the altitude of high-frequency jetting sources when time delays generated by topography are not accounted for.…”