The Features of Dead Band AMT Signal in Chukotka Region
In this paper we analyze the amplitude spectra of the audiomagnetotelluric (AMT) natural-source signal. Special attention is given to the signal in the frequency range from 1 to 5 kHz known as “dead band”. We study the measurements of the base sites that were used during summer fieldwork in 2013, 2014 and 2017 in Chukotka Region (Russian Far East). The area is located above the Arctic Circle. As it has been described by previous researchers, the stable signal in the dead band can be acquired only at nighttime. We would like to point out that in the daytime the local maximum at 2.4 kHz frequency is observed within the dead band in Chukotka. The 2.2 and 2.6 kHz frequencies can be reconstructed by using more than 3 h of daytime data acquisition. These frequencies can be used as the ranging marks. These ranging marks sometimes allow reconstructing the AMT curve by using the relationship between the amplitude and phase. We present a proposal for improving data quality in the dead band during the daytime.
KeywordsMagnetotellurics Magnetovariational profiling EM monitoring Amplitude spectra Dead band
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