FIRE GAS PLUMES DURING THE 1927 YALTA EARTHQUAKES

Abstract

In the Black Sea near Yalta in 1927 there were massive methane outbursts, accompanied by flames over the water. The fire was associated with methane emissions that entered through tectonic faults. The faults were caused by seismic movements. The article analyses the depth structure of the focal zones and the nature of the seismic process and assesses the nature of the manifestations of the fires. The main factor is thought to be methane, which rises from the earth’s crust during earthquakes. The electric spark discharges generated by friction and collision of the earth’s crust ignited methane gas. The massive gas emissions of millions of cubic meters that can be called gas plumes have been fixed. The spatial and temporal direction of the fire phenomena has been established. The main fire outbreaks over the water extended in two directions. The first, the Sevastopol­Evpatoria zone, stretches submeridionally to the coast and follows the Mykolayiv fault system. The second one is the Yalta­ Alushta zone with north-eastern extension. It is associated with tectonic faults within the Circum­Black Sea region, fault zone. This fault zone is active even at present, as indicated by seismicity, the structure of the consolidated crust and sedimentary strata, bottom topography forms, etc. Analysis of geological and geophysical materials, and seismicity of the northern Black Sea region, indicate that the fire events during the Yalta earthquakes in 1927 were caused by massive methane ejections as a result of a powerful mantle gas-fluid flow into the dissolved zones of the crystalline basement along the tectonic faults of different scales within the Odessa­Sinop and Circum Black Sea fault zones. Earthquakes triggered the activation of tectonic faults in benthic sedimentary horizons for the migration of focused deep-seated gas-fluid streams.