Infrasound Signals and Their Source Location Inferred from Array Deployment in the L&amp;#252;tzow-Holm Bay Region, East Antarctica: January-June 2015

Takahiko Murayama,Masa-Yuki Yamamoto,Yoshiaki Ishihara,Masaki Kanao

doi:10.4236/ijg.2017.82007

Abstract

Characteristic features of infrasound waves observed in the Antarctic represent a physical interaction relating surface environment in the continental margin and surrounding Southern Ocean. Source location of several infrasound events is demonstrated by using combination of two array deployments along a coast of the Lützow-Holm Bay (LHB), East Antarctica, for data retrieving period in January-June 2015. These infrasound arrays being established in January 2013 clearly detected temporal variations in frequency content and propagation direction of the identified seven large events. Many of these sources are assumed to have cryoseismic origins; the ice-quakes associated with calving of glaciers, discharge of sea-ice, collision between sea-ice and icebergs around the LHB. Detail and continuous measurements of infrasound waves in the Antarctic are a proxy for monitoring regional environment as well as climate change in high southern latitude.

Highlights

“Infrasound waves” are defined as subaudible sounds—pressure waves with frequencies ranging from the cut-off frequency of sound
Characteristic features of infrasound waves observed in the Antarctic represent a physical interaction relating surface environment in the continental margin and surrounding Southern Ocean
These infrasound arrays being established in January 2013 clearly detected temporal variations in frequency content and propagation direction of the identified seven large events

Summary

Introduction

“Infrasound waves” are defined as subaudible sounds—pressure waves with frequencies ranging from the cut-off frequency of sound The infrasound can be effectively used for remote sensing of physical aspects of the Earth’s atmosphere, compared with seismic waves in the same frequency range recorded by a seismometer. Time-space variations in atmospheric pressure are excited by physical interaction between the atmosphere, oceans, cryosphere, and the surface of solid earth. These interactive phenomena are involved in surface environmental variations and their generating sources can be measured by using infrasonic waves in polar region. Two infrasound arrays with different diameters were deployed on the outcrop site at SYO together with the second array on continental ice sheet near the eastern coast of LHB. Plausible source mechanism of these events is discussed regarding surface environmental change, in particular cryosphere dynamics surrounding the LHB

Array Deployments

Analyses and Discussion

Conclusion