Arie (Lev) Gilat and Alexander Vol
Based on results of our tectonic-geochemical researches in the western Dead Sea area, which were published only as not easily accessible conference abstracts, proceedings, etc., as well as on new very relevant publications on Plio-Pleistocene mud-volcanism there, we attempt to show that some of the tectonic earthquakes in the area resulted in thermobaric-hydrothermal explosions and fires. This natural mechanism produced breccias with open spaces, concentric and radial fractures, caves and the patina containing micro-particles of soot and metals. Explosions of mini and medium scale have been apparently generated by earthquake-expelled heated to 120-150?C hydrothermal liquid transporting light hydrocarbons and hydrogen-sulfide. When reaching near atmospheric pressure it instantly becomes steam with corresponding volume increases of up to 1700 times. These give rise to the pulverization of hydrothermal stream and the escape of gases, and lower ignition temperatures of hydrocarbons and hydrogen sulfide; sparks ignite volatiles, ionized steam and atmospheric oxygen are oxidizers. Sparking is produced mostly by electricity, resulting from interaction of a high-velocity stream of a wet steam with solids. It is thought that not only Sodom and Gomorrah, but also other historical conflagrations devastating cities immediately after earthquake may have been caused by natural ignition of earthquake-expelled combustible gases. In case of very large volume of expelled gases the fire will appear high above the ground, on the uplifted by its intrusion contact-zone with the atmospheric oxygen; the fire will go down when the gas-stream lessens. Author’s recommendation is that for prevention of major disasters, the construction-sites chosen for important nuclear or chemical plants in areas covered by loose sediments or in the vicinity of rivers should be examined for possible closeness to capable faults. Mapping of the He-outflow intensity is highly recommended. This is especially relevant in areas with known hydrocarbon occurrences and mud-volcanoes.