M. Rapisarda, Atlantis, Geology of Atlantis, Explosive eruptions

As often happens in science fiction b-movies, flooding at the end of the Ice Age were also accompanied by tremendous volcanic eruptions. When the ice covering a continental plate melts, the lesser weight over the plaque can generate an instability. The continental plates floating on Earth's mantle, can be compared to a row of boats moored side by side. If the occupant of a boat suddenly plunges into the water, the boat starts to oscillate, varying the distance from nearby boats, both in height and length. A similar movement happens among contiguous plates, reassessing after the melting of a glacier. Because of these tensions, the layer of earth's crust along the separation thins and deforms, allowing the underlying magma to reach the surface and generate new volcanoes.

For their part volcanoes, spewing ashes into the stratosphere, interfere with the sunlight reflection and can cause a cooling (or heating) of the atmosphere, originating climate variations. The cause and effect relationship between climate and volcanic eruptions is complicated, but it is well accepted that climate changes have been almost always accompanied by an increase of volcanic activity.

This correlation has been observed during the Quaternary (Bray, 1977), (Hall, 1982) and is valid also in the central Mediterranean (Paterne, Guichard & Labeyrie, 1988). In fact it turned out that climate changes in the last 110,000 years have been coupled with explosive volcanic activity (Zielinski et al., 1996). For example, in the Mediterranean, between 15,000 and 8,000 years ago, in concurrence with the largest changes in sea level, the number of explosive eruptions tripled, reaching a rate of three per millennium (McGuire, 1997). It could not be a coincidence that the beginning of the Holocene has been accompanied, 11,300 years ago, by a terrible eruption, as witnessed by the largest peak of SO4 found in Greenland in the last 110,000 years (Zielinski et al., 1996).

Comparison between Ca2/ time series, a proxy for changing climatic conditions (Mayewski et al., 1994), and volcanic SO4 > 40 ppb from EOF-5 time series for the past 20,000 yr (A). The Younger Dryas interval is noted by YD. Arrows indicate stadial/interstadial transitions that are characterized by a large number of volcanic signals or a very large signal. High Ca2/ concentrations reflect colder climatic conditions, whereas low Ca2/ concentrations reflect warmer climatic conditions. Note changes in scale between each plot for both ion species (adapted from Zielinski et al., 1996).

Bray, J. R. (1977) Pleistocene volcanism and glacial initiation. Science 197, 251–254.

Hall, K. (1982) Rapid deglaciation as an initiator of volcanic activity: an hypothesis. Earth Surf. Process. Landforms 7, 45–51.

McGuire, W. J., R. J. Howarth, C. R. Firth, A. R. Solow, A. D. Pullen, S. J. Saunders, I. S. Stewart & C. Vita-Finzi (1997) Correlation between rate of sea-level change and frequency of explosive volcanism in the Mediterranean. Nature 389, 473-476.

Paterne, M., Guichard, F. & Labeyrie, J. (1988) Explosive activity of the south Italian volcanoes during the past 80,000 years as determined by marine tephrochronology. J. Volcanol. Geotherm. Res. 34, 153–172.

Zielinski, G. A., Mayewski, P. A., Meeker, L. D., Whitlow, S. & Twickler, M. S. (1996) An 110,000-year record of explosive volcanism from the GISP2 (Greenland) ice core. Quat. Res. 43, 109–118.

Explosive eruptions Versione italiana