Volcanic sounds: Investigation and analysis

Abstract

Volcanic sounds were tape‐recorded on ten occasions during the decade 1950–1960. Analyses of the recordings show that underwater sounds from Bárcena volcano in the north‐eastern Pacific, in November 1952, possessed frequencies in a strong harmonic progression with an apparent fundamental frequency of about 50 cps, little energy above 550 cps, and a pulse duration of 1 to 2 sec. Airborne sounds of explosions in Mihara Yama, O Shima volcano, Japan, in January 1954 had an apparent fundamental frequency of 16 to 17 cps, a strong harmonic progression, and a pulse duration of 0.5 to 1 sec. Less violent explosive activity of the same volcano in September 1950 produced essentially broad‐band acoustic energy, with sound durations of 1 to 2 sec. Recorded airborne sounds of Izalco volcano, El Salvador, in 1956, were similar to those from O Shima in 1950, but had longer pulses. Capelinhos volcano, Azores, in 1958 generated the following airborne sounds: crater explosions had maximum energy below 50 cps and little energy above several hundred cycles; eruptions of liquid lava from the crater produced broad‐band sonic energy; and almost all energy of pressure waves or flashing arcs was below 50 cps. It is suggested that the quality of recorded sounds is related to the types of volcanic activity defined by Lacroix and in this paper: Hawaiian eruptions tend to be acoustically quiet; strombolian activity is characterized by broad‐band sounds that may show a fundamental frequency and harmonics of small intensity; and vulcanian eruptions are denoted by a marked fundamental frequency and strong harmonics of relatively large intensity. Peléan activity has not been recorded. Recording instrumentation and analytical procedure in which sound pressure level‐frequency and frequency‐time methods were used are briefly discussed as an aid to those wishing to make similar investigations.

An overview of volcano infrasound: From hawaiian to plinian, local to global

“…each have characteristic acoustic signals as well, as first documented by Richards (1963). In this section we describe the typical infrasound signals associated with the predominant types of volcanic activity, as well as the models used to explain them.…”

“…The first tape recordings of volcanic sounds were apparently made by the NHK Broadcasting Bureau of Japan (Snodgrass and Richards, 1956). In 1952, a program of volcanic acoustics was initiated by James Snodgrass at the Scripps Institution of Oceanography, leading to a decade's worth of underwater and airborne acoustic recordings of volcanic sounds (Richards, 1963), however, the sonobuoy-based recording systems had a poor frequency response below 50 Hz. Richards (1963) provided a table summarizing the results of their investigations, which describes acoustic signals recorded from various idealized styles of volcanic activity.…”

“…In 1952, a program of volcanic acoustics was initiated by James Snodgrass at the Scripps Institution of Oceanography, leading to a decade's worth of underwater and airborne acoustic recordings of volcanic sounds (Richards, 1963), however, the sonobuoy-based recording systems had a poor frequency response below 50 Hz. Richards (1963) provided a table summarizing the results of their investigations, which describes acoustic signals recorded from various idealized styles of volcanic activity. We have attempted to provide an update of the table by Richards as Table 1, incorporating recent advances in volcano acoustics and infrasonics (Section 4).…”

Nature, wavefield properties and source mechanism of volcanic tremor: a review

“…11) prompted researchers to investigate the possibility of a common link between the two phenomena. Even though it has been well known that volcanic eruptions can generate pressure disturbances in the atmosphere with a frequency that can range between 10 33 and 20 Hz (Richards, 1963), until recently there was no systematic recording of temporal variations of these signals near erupting volcanoes. Nowadays the installation of very sensitive microphones that record air-pressure waves with high resolution is an important supplement to the seismic monitoring of active volcanoes (Stromboli-Ripepe et al, 1996 ; Pavlof-Garce ¤s and Hansen, 1998; ArenalGarce ¤s et al, 1998; Sakurajima-Garce ¤s et al, 1999 ; Karimsky/Sangay-Johnson and Lees, 2000; Mt.…”

Acoustic Noise from Volcanoes: Theory and Experiment

“…Wilcox reported 1 1 distinct sounds associated with activity at Paricutin including a deep throaty roar resulting from the rush of vapours at a small vent and a low growl from intermittent emission of a similar vent (Foshag & Gonzalez 1956, p. 363-364). Richards (1963) studied airborne and submarine noise from 10 volcanic events and found that the characteristics of recorded sounds were related to the type of volcanic activity producing them. For example he found that Hawaiian-type eruptions tend to be acoustically quiet, strombolian activity is characterized by broad-band noise with a moderately well-developed fundamental frequency and harmonics of small intensity, and vulcanian eruptions by a marked peak fundamental frequency and very well-developed harmonics.…”