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Detection of earthquake precursor using electromagnetic wave propagation fluctuation

We proposed a method of earthquake precursor detection using radio wave propagation changes.

 

Radio wave propagation changes daily as shown in Fig. 1 when reflected from the ionosphere. But it is often observed that it changes differently as shown in Fig. 2 a few days before earthquake occurrences.

Fig. 1 Normal daily change of radio wave propagation when reflected from the ionosphere.

Fig. 2 Abnormal change of radio wave propagation is observed before earthquake.

We paid special attention to the propagation change patterns of waves in the LF, MF, and VHF bands transmitted from broadcasting stations, standard radio stations, and radio beacon stations, and developed a detection system that compares the measured daily waves with normal daily wave patterns using pattern recognition methods.

 

The developed algorithm gives an earthquake precursor evaluation value day by day using the correlation values. In addition, we took account of consider the effect of the solar activity and a geomagnetism fluctuation on the evaluation values.

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Fig. 3 Algorithm for detecting electromagnetic wave propagation fluctuation.

We analyzed the Great East Japan Earthquake (March 11, 2011)  with this system.

 

Evaluation values from Aug. 2010 to Apr. 2011 are shown in Figures 4 to 6. A high evaluation value means a larger propagation change. 

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We confirmed the validity of the system. As a result, all precursors of big earthquakes of magnitude more than 7 on the Richter scale were detected and 70% of precursors of earthquakes of magnitude from 5 to 7 were detected.

Fig. 4  Evaluation values in Aug. 2010.

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Fig. 5  Evaluation values from Jan. to Feb. in 2011.

Fig. 6  Evaluation values from Mar. to Apr. in 2011.

Red arrow shows the occurrence of the Great East Japan Earthquake (March 11, 2011) . Red dotted line is considered the precursor of the earthquake. 

Papers:

  1. Yuta Nakamura, Masayoshi Tanaka, Study on Earthquake Precursor Detection using LF-band Radio Wave Propagation Change， IEICE， general conference， B-1-15,p15，2012.03.  Ref. pdf

  2. Masayoshi Tanaka, Yuta Nakamura, Study on Earthquake Forecast using Electromagnetic Wave Propagation Fluctuation -Propagation Fluctuation before and after Great Eastern Japan Earthquake-, Proceeding of Academic Conference of Nihon University, College of Industrial Technology, OS-1, pp1263-1266, 2011, ISSN 2186-5647. ⇒ Ref. pdf (English)

  3. Yuta Nakamura, Masayoshi Tanaka, Study on LF-band Radio Wave Propagation Change before and after Eastern Japan Earthquake, IEICE， society conference， B-1-3,p3，2011.09.  Ref. pdf

  4. Yuta Nakamura, Masayoshi Tanaka, A study on precise detection of LF and VHF band radio wave propagation change for earthquake forcasting, IEICE， General Conference, B-1-38,p.38(2011) Re.f pdf

  5. Yuta Nakamura, Masayoshi Tanaka :長波の電波伝搬変動を用いた地震予知の研究，第43回日本大学生産工学部学術講演会,2-12,pp39(2010)

  6. 金井紳太郎,田中將義 :第40回日本大学生産工学部学術講演会,2-27(2007)

  7. 宮澤達博,田中將義 :第40回日本大学生産工学部学術講演会電気電子部会講演概要,2-28(2007)

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