Self-induced magma fractures, or dikes, are believed to be the dominant mechanism by which basaltic melts propagate through the lithosphere and the Earth's crust. Theoretical modeling and field observations help us to understand the essential physics of magma migration from its source to its final destination in the upper lithosphere.

Currently, most of the Earth's mafic volcanism occurs at the mid-ocean ridges and "hot spots" (e.g., basaltic shield volcanoes such as those of Hawaii and Galapagos islands). From the geological record we also know about the third type of mafic volcanism - the so-called flood basalt events - that occurred more or less periodically in the past and generated massive outpourings of mafic lavas covering tens of thousands of square kilometers of the Earth surface in a relatively short time (a few million years or less). It has been suggested that these flood lavas may be a cause of mass extinctions that wiped out much of life on Earth many times in the past. In collaboration with Prof. Allan Rubin of Princeton University I developed theoretical models of heat and mass transfer during the emplacement of giant dike swarms that are believed to be the feeder conduits for flood basalts.

Figure below illustrates one possible scenario of the emplacement of a giant dike swarm in which dikes propagate down a topographic slope generated by a buoyant mantle plume head.

Mantle plumes are now generally believed to be the ultimate source of the flood magmatism, although the subject remains controversial. Our calculations suggest that the exceedingly large dike widths observed in the field (up to hundreds of meters and more) could be produced by massive thermal erosion of the host rocks during dike emplacement and may be indicative of very large magma flow rates (rather than very high excess magma pressures). This may explain some intriguing field observations of an apparent non-dilatant emplacement of at least several giant dikes around the world.

For more details please see these papers:

• Fialko, Y., Y. Khazan, and M. Simons, Deformation due to a pressurized horizontal circular crack in an elastic half-space, with applications to volcano geodesy, Geophys. J. Int., 146, 181-190, 2001 (download PDF)
• Fialko, Y., M. Simons, and Y. Khazan, Finite source modeling of magmatic unrest in Socorro, New Mexico, and Long Valley, California, Geophys. J. Int., 146, 191-200, 2001 (download PDF)
• Fialko, Y., and M. Simons, Deformation and seismicity in the Coso geothermal area, Inyo County, California: Observations and modeling using satellite radar interferometry, J. Geophys. Res., 105, 21,781-21,794, 2000 (download PDF)
  

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