Time–space variations in infrasound sources related to environmental dynamics around Lützow–Holm Bay, east Antarctica

Murayama, Takahiko; Kanao, Masaki; Yamamoto, Masa Yuki; Ishihara, Yoshiaki; Matsushima, Takeshi; Kakinami, Yoshihiro; Okada, Ken-ichi; Miyamachi, Hiroki; Nakamoto, Masahiko; Takeuchi, Yukari; Toda, Shigeru

doi:10.1016/j.polar.2017.10.001

Cited by 9 publications

(10 citation statements)

References 16 publications

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“…Three infrasound events in 2015 were also identified by using the two arrays deploying at SYO and S16, and the excitation source locations were determined along the coast, inside the sea ice and surrounding the islands [11]. Moreover, the long-term variability of the source location of the infrasound excitation for 8 months in January-August 2015 was investigated by using the same arrays [12]. Plausible source mechanisms of these events were estimated regarding the surface environmental change, in particular, cryosphere dynamics surrounding the LHB.…”

Section: Introductionmentioning

confidence: 99%

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Characteristic Infrasound Events Associated with Sea-Ice Discharges in the Lützow-Holm Bay of Antarctica: April 2016

Murayama¹,

Kanao²,

Yamamoto³

2019

Antarctica - A Key to Global Change

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Infrasound waves detected in Antarctica contain information on the physical interaction among the surface environment at the margin of the continent and surrounding ocean. Time-space variation of source location for infrasound excitation during mid-April 2016 was investigated by using a combination of two arrays deployed along the coast of the Lützow-Holm Bay (LHB), East Antarctica. The infrasound array observations detected temporal variations in distance from the sources and propagation direction. A few tens of infrasound events were identified during 10 days of the period, and many of them located in the northward direction from the array stations were inside the LHB and offshore in the Southern Indian Ocean. Many of the events had predominant frequency content of few Hz, which were higher than microbaroms generated from the ocean. By comparing with MODIS satellite image at the same period, these sources were considered to be the ice-related phenomenon associated with the discharge of fast sea ice from the LHB.

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Section: Introductionmentioning

confidence: 99%

“…Schematic illustration of interdisciplinary physical interaction within multi-spheres in the Antarctic. Several kinds of seismic, infrasonic, and hydroacoustic waves are generated by surface environmental sources (after [12]).…”

Section: Introductionmentioning

confidence: 99%

Characteristic Infrasound Events Associated with Sea-Ice Discharges in the Lützow-Holm Bay of Antarctica: April 2016

Murayama¹,

Kanao²,

Yamamoto³

2019

Antarctica - A Key to Global Change

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“…Figure 8. Power spectral densities of infrasound data recorded at SYO (one of the array sites; C1; [19]) during April 2015. High amplitudes in spectral densities were appeared at stormy days.…”

Section: Discussionmentioning

confidence: 99%

“…On 18 April, an iceberg (the same as of the middle one in Figure 3 The colored circles are the source location estimated by infrasound arrays deploying at SYO and S16 (red triangles) during one day on 18 April (modified after [19]). Colors of the source location circles correspond the source origin time from the beginning of the day (from blue, green, yellow and orange).…”

Section: -19 April 2015mentioning

confidence: 99%

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Seismic Tremors and Their Relation to Cryosphere Dynamics in April 2015 around the Lützow-Holm Bay, East Antarctica

Kanao¹,

Murayama²,

Yamamoto³

et al. 2017

IJG

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Characteristics and statistics of seismic tremors occurring during April 2015 were investigated by using short-period and broadband seismographs deployed at Syowa Station (SYO), in the Lützow-Holm Bay (LHB), East Antarctica. In order to examine a relationship between surface environments in particular cryosphere variation, the MODIS satellite images were utilized for comparison with the detected tremor events. Since a large volume of sea-ice was discharged during the April, together with several large icebergs passed through from the west to the east at northern edge of the fast sea-ice of LHB, it was expected to detect seismic tremors involving cryospehre dynamics. During the month, a total number of 49 tremor events including short duration ice shocks were identified. Majority of the events (N = 39) had their duration times more than 15 minutes, which were divided into both tremors and ice shocks on the basis of experienced definition at SYO. Cryospheric sources recorded by seismic tremors were classified into several origins (collision, calving, crevassing, crashing, etc.): "crevassing events" along the large cracks inside the fast sea-ice in LHB (04 April), "discharge events" of fast sea-ice from the Bay (07 April), "collision events" between iceberg and the edge of fast sea-ice (14 April), "crashing movement" between fragmentation of fast sea-ice and packed sea-ice (18 April), and other origins. In particular, strong amplitude tremors with harmonic overtones were assumed to be occurred independently from whether condition, because these overtone tremors were identified at less stormy days by comparison with infrasound data at SYO.

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Natural and Anthropogenic Sources of Seismic, Hydroacoustic, and Infrasonic Waves: Waveforms and Spectral Characteristics (and Their Applicability for Sensor Calibration)

et al. 2022

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The record of seismic, hydroacoustic, and infrasonic waves is essential to detect, identify, and localize sources of both natural and anthropogenic origin. To guarantee traceability and inter-station comparability, as well as an estimation of the measurement uncertainties leading to a better monitoring of natural disasters and environmental aspects, suitable measurement standards and reliable calibration procedures of sensors, especially in the low-frequency range down to 0.01 Hz, are required. Most of all with regard to the design goal of the Comprehensive Nuclear-Test-Ban Treaty Organisation’s International Monitoring System, which requires the stations to be operational nearly 100% of the time, the on-site calibration during operation is of special importance. The purpose of this paper is to identify suitable excitation sources and elaborate necessary requirements for on-site calibrations. We give an extensive literature review of a large variety of anthropogenic and natural sources of seismic, hydroacoustic, and infrasonic waves, describe their most prominent features regarding signal and spectral characteristics, explicitly highlight some source examples, and evaluate the reviewed sources with respect to requirements for on-site calibrations such as frequency bandwidth, signal properties as well as the applicability in terms of cost–benefit. According to our assessment, earthquakes stand out across all three waveform technologies as a good natural excitation signal meeting the majority of the requirements. Furthermore, microseisms and microbaroms allow a calibration at very low frequencies. We also find that in each waveform technique man-made controlled sources such as drop weights or air guns are in good agreement with the required properties, although limitations may arise regarding the practicability. Using these sources, procedures will be established allowing calibration without record interrupting, thereby improving data quality and the identification of treaty-related events.

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Time–space variations in infrasound sources related to environmental dynamics around Lützow–Holm Bay, east Antarctica

Cited by 9 publications

References 16 publications

Characteristic Infrasound Events Associated with Sea-Ice Discharges in the Lützow-Holm Bay of Antarctica: April 2016

Characteristic Infrasound Events Associated with Sea-Ice Discharges in the Lützow-Holm Bay of Antarctica: April 2016

Seismic Tremors and Their Relation to Cryosphere Dynamics in April 2015 around the Lützow-Holm Bay, East Antarctica

Natural and Anthropogenic Sources of Seismic, Hydroacoustic, and Infrasonic Waves: Waveforms and Spectral Characteristics (and Their Applicability for Sensor Calibration)

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Time–space variations in infrasound sources related to environmental dynamics around Lützow–Holm Bay, east Antarctica

Cited by 9 publications

References 16 publications

Characteristic Infrasound Events Associated with Sea-Ice Discharges in the Lützow-Holm Bay of Antarctica: April 2016

Characteristic Infrasound Events Associated with Sea-Ice Discharges in the Lützow-Holm Bay of Antarctica: April 2016

Seismic Tremors and Their Relation to Cryosphere Dynamics in April 2015 around the L&#252;tzow-Holm Bay, East Antarctica

Natural and Anthropogenic Sources of Seismic, Hydroacoustic, and Infrasonic Waves: Waveforms and Spectral Characteristics (and Their Applicability for Sensor Calibration)

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Seismic Tremors and Their Relation to Cryosphere Dynamics in April 2015 around the Lützow-Holm Bay, East Antarctica