Materials of the International Conference
50th Anniversary of the International Geophysical Year
and Electronic Geophysical Year

16-19 September 2007 • Suzdal, Russia

Ground-based electromagnetic (EM) observations and monitoring of volcanoes and earthquakes

J. Zlotnicki1, J. L. Le Mouël2, A. Gvishiani3, R. P. Singh4, M. Rodkin3, G. Vargemezis5, Sh. Bogoutdinov3, S. Agayan3, and A. Senthilkumar1

1UMR 6524, CNRS-OPGC, Clermont-Ferrand, France

2Laboratoire de Gèomagnètisme, I.P.G.P., France

3Geophysical Center, Russian Academy of Sciencrs, Moscow, Russia

4Indian Institute of Technology, Kanpur, India

5Aristotèles Laboratory, University, Thessaloniki, Greece

Abstract

Earthquakes and volcanic eruptions, as well as their induced effects (lahars, mud flows, tsunamis, landslides, etc), belongs to the highest catastrophic natural events. In a few decades, hundreds of thousands people are killed, and about twice more are injured. These events cost billions of dollars, and break down the economy and the societal tissue for months to years. Most of the countries on Earth are concerned by at least one of these events. A lot of efforts are done to understand the mechanisms generating earthquakes and volcanic eruptions, to draw hazards maps, and hopefully to forecast these catastrophes. The studies in electromagnetism (EM) have enough progressed to be considered as a promising methodology. The main periods are recalled hereafter. Up to about fifteen years, researches and monitoring systems have been progressively developed in each country with local human and technical capabilities. Studies started with visual observations, followed in the 1940's by manual and repeated measurements. It is only in years 1970 and later that autonomous and self-recording analog sensors were progressively set on the field. Only a few numbers of sensors were operating on the field in regard to the scale of the hazard zones to monitor (~10 km2 to ~1000 km2). Data processing was performed by hand from paper's records. This time consuming task only allowed to process slow sampling measurements. PC computers completely changed the way to work in the years 1980, although their memory and their mass storage were insufficient at the beginning. Digital sensors appeared, data transmission was implemented up to local observatories where data were collected and processed. At that time, observations became more and more accurate, reliable and better controlled. During this period a lot of findings were done and national teams were led to compare their observations. This fruitful period prompted teams to start international cooperation's. The internationalization of researches on common topics partly suppressed the lack of man power in national teams, and improved the value of the researches. Hence, different methods started to be combined, and jointed data processing became a key issue to analyze in detail natural phenomena. For example, in 1994, several electromagnetic methods were associated to monitor the unrest of Miyake-jima volcano, in Japan. Different types of signals progressively appeared and increased, till the 2000 eruption, and combined data processing allowed building a coherent model of the volcano unrest. If some requirements are satisfied (enough sensors on the field, on-line data and processing, real-time analysis) eruptions would be most often forecast. Finally, after 2000, huge power increase of PC computers, use of Internet links for communication and data transfers have produced a new step in observing natural hazards. Monitoring systems become very powerful and high frequency data acquisition systems allow to process the complete domain of EM signals (up to tens of kHz). Adding satellite data, as Demeter mission, monitoring natural hazards overcome national researches; individual international teams bring their specific skill into a common project. As example, teams from France, Russia, India, and Greece started to build a Virtual EM laboratory for better understanding and monitoring volcanic eruptions and earthquakes. In particular, a great effort will be done on Earthquakes for which the forecast is not achieved at present.

Citation: J. Zlotnicki, J. L. Le Mouël, A. Gvishiani, R. P. Singh, M. Rodkin, G. Vargemezis, Sh. Bogoutdinov, S. Agayan, and A. Senthilkumar (2007), Ground-based electromagnetic (EM) observations and monitoring of volcanoes and earthquakes, in: Materials of the International Conference '50th Anniversary of the International Geophysical Year and Electronic Geophysical Year', GC RAS, Moscow, doi:10.2205/2007-IGY50conf.

© 2007 Geophysical Center RAS and authors


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