Precursory signals related to earthquakes are still a matter of debate. Signals prior to volcanic activities are better identified.

Among all the techniques available in these researches, magnetic, electric and electromagnetic (EM) are becoming powerful tools.

Some examples are now well established, but they are often based on a few parameters recorded on sparse equipments long term systematic observations in the frame of multidisciplinary would be a key issue for better understanding Natural Hazards.

Self-Potential signals prior to March 9, 1998 eruption of La Fournaise Volcano. Records at 5 independents electric stations (Zlotnicki et al., 2001)	Total field magnetic sygnals recorded before eruptive events on Merapi volcano (Indonesia)

VEML fills this gap by combining multi-parametric EM techniques and by integrating them with other disciplines (seismology, geodesy, geochemistry, geology and so forth). Researches are based on ground observations, as well as on satellites ones (DEMETER, MOPITT, ASTER …).

The two main volcanic targets are La Fournaise (Reunion Island) and Taal (Philippines) volcanoes.

The two major seismic targets are Corinth gulf rift (Greece) and Tianzhu fault (China).

Further developments could be achieved on Kamchatka (Russia) and Hachijo-jima (Japan) volcanoes.

Magnetic field amplitude as a function of time during the 2 days before and 4 days after the Loma Prieta earthquake ( Fraser-Smith et al., 1990)	Statistical study of the electric field recorded on board of DEMETER satellite (Parrot et al., 2007). Statistical change in the energy of electric field prior to Earthquakes of mag 5.5