Abstract

Gravimetry as a geophysical technique can be applied in various fields of geosciences. Typically it is used in exploration for mineral resources, geoengineering, basic geological research, archaeology, etc. In this paper the focus is concentrated on discovering unknown maar structures and monitoring of volcanic activity in Greek volcanic islands of Nisyros and Santorini (Thira). Maar structures may not be simply visible in morphology and gravity surveys proved that they are characterized by striking negative gravity anomalies of about 2 to 5 mGal. Six till then unknown maars were discovered in the western Bohemian Massif in Central Europe.<br /> Mass changes in the intrusive system of volcanoes may be reflected in gravity monitoring data. The author performed such repeated observations of gravity field in the two Greek islands. It turned out that in both cases the data show certain unrest of the volcanic system, while especially in Thira an extensional process related to the new Kolumbo submarine volcano seems to continue.