Abstract
We have studied the electric \(\vec {E}\) and magnetic \(\vec {B}\) fields by displaying the arrival directions through a 2D image named spectral-directionalogram (SD-gram). This technique maps electromagnetic field directions in time and frequency space. We tested the method through modeling experiments. An exclusive case is explained theoretically. In addition, method is applied on the two field data sets. One was acquired on the land and other in the ocean. The land data, is studied for the 50 Hz and harmonics. The frequencies are continuous in the direction during a time range, while splittings are observed during the other. In the second example, we have used marine electromagnetic data. The spectrogram suggests two anomalies, one close to 1 Hz and the other having a broad spectral range between 1 to 0.08 Hz. We hypothesize two possible causative sources, microseisms and degassing of a mud volcano. Out of these two choices, one can be easily falsified using the SD-gram. These examples highlight the usefulness of the technique in the data analysis. Moreover, the electromagnetic noise caused by the ocean waves have different spectral damping characteristics compared to those of plane waves. Therefore, we are proposing a new damping relation for the ocean, where dispersion is a dominant case.
Similar content being viewed by others
References
Baba K (2005) Electrical structure in marine tectonic settings. Surv Geophys 26(6):701–731
Bendat J, Piersol A (2011) Random data: analysis and measurement procedures. Wiley series in probability and statistics. Wiley
Bhatt KM (2011) Motion induced noise in marine electromagnetic data. Ph.D. thesis, Technical University Braunschweig, Braunschweig, Germany
Bhatt KM (2014) Microseisms and its impact on the marine-controlled source electromagnetic signal. J Geophys Res 119(12):8655–8666. https://doi.org/10.1002/2014JB011024
Bhatt KM, Hördt A, Heinstein T, Barnawal V (2010) Spectral-directionalogram: representing the directions of the registered frequencies in time. In: 20 international electromagnetic induction workshop, Giza, Egypt
Calvert W (1985) De 1 measurements of AKR wave directions. Geophys Res Lett 12(6):381–384. https://doi.org/10.1029/GL012i006p00381
Chave AD (1983) On the theory of electromagnetic induction in the earth by ocean currents. J Geophys Res 88(B4):3531–3542. https://doi.org/10.1029/JB088iB04p03531
Cohen L (1989) Time-frequency distributions-a review. Proc IEEE 77(7):941–981
Constable S (2010) Ten years of marine CSEM for hydrocarbon exploration. Geophysics 75(5):75A67-75A81. https://doi.org/10.1190/1.3483451
Evtushenko YG (1985) Numerical optimization techniques. Springer, Berlin
Gabor D (1946) Theory of communication. J Inst Electric Eng (Lond) 93(3):429–457
Green PE, Kelly EJ, Levin MJ (1966) A comparison of seismic array processing methods. Geophys J Int 11:67–84
Jackson JD (1998) Classical Electrodynamics, 3rd edn. Wiley, New York
Kedar S, Longuet-Higgins MS, Webb F, Graham N, Clayton R, Jones C (2008) The origin of deep ocean microseisms in the north Atlantic ocean. Proc R Soc Math Phys Eng Sci 464:777–793
Knight WC, Pridham RG, Kay SM (1981) Digital signal processing for sonar. Proc IEEE 69(11):1451–1506
Longuet-Higgins MS (1948) Sea wave and microseisms. Nature 162:700
Longuet-Higgins MS (1950) A theory of the origin of microseisms. Philos Trans R Soc A 243(857):1–35
Løseth LO (2011) Insight into the marine controlled-source electromagnetic signal propagation. Geophys Prospect 59(1):145–160
Manoj C, Kuvshinov A, Neetu S, Harinarayana T (2010) Can undersea voltage measurements detect tsunamis? Earth Planets Space 62(3):353–358
Park C (2015) 2d discrete Fourier transform on sliding windows. IEEE Trans Image Process 24(3):901–907
Rodney AV, Coates FW (1990) Underwater acoustic systems. Macmillan Education Limited, London
Rost S, Thomas C (2002) Array seismology: methods and applications. Rev Geophys 40(3):1008. https://doi.org/10.1029/2000RG000100
Sanford TB (1971) Motionally induced electric and magnetic fields in the sea. J Geophys Res 76(15):3476–3492
Toh H, Satake K, Hamano Y, Fujii Y, Goto T (2011) Tsunami signals from the 2006 and 2007 Kuril earthquakes detected at a seafloor geomagnetic observatory. J Geophys Res 116(B2):1–10
Tuncer TE, Yasar TK, Friedlander B (2009) Chapter 4—Narrowband and wideband DOA estimation for uniform and nonuniform linear arrays. Academic Press, Boston
Wassermann J (1997) Locating the sources of volcanic explosions and volcanic tremor at Stromboli volcano (Italy) using beam-forming on diffraction hyperboloids. Phys Earth Planet Inter 104(1–3):271–281
Webb S, Cox C (1982) Electromagnetic fields induced at the seafloor by Rayleigh-Stoneley waves. J Geophys Res 87(B5):4093–4102
Weidelt P (2007) Guided waves in marine CSEM. Geophys J Int 171(1):153–176
Welch PD (1967) The use of fast Fourier transform for the estimation of power spectra: a method based on time averaging over short, modified periodograms. IEEE Trans Audio Electroacoust 15(2):70–73
Acknowledgements
The corresponding author (KMB) is thankful to KMS Technologies-KJT Enterprises Inc. and NGRI for the data sets. Prof A Hördt contribution is significant and can not be thanked in words. The data is having the DOI 10.6084/m9.figshare.13032989. Thanking director NGRI, Dr. V M Tiwari, for the graceful permission to publish the work. Financial support of MLP0001-28-FBR-01 is highly acknowledged. We are thankful to the reviewers for the constructive comments.
Author information
Authors and Affiliations
Corresponding author
Additional information
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
About this article
Cite this article
Bhatt, K.M., Manglik, A. Oceanic EM damping and spectral splitting by the SD-gram. Mar Geophys Res 42, 32 (2021). https://doi.org/10.1007/s11001-021-09454-w
Received:
Accepted:
Published:
DOI: https://doi.org/10.1007/s11001-021-09454-w