The viscosity of basaltic magma; an analysis of field measurements in Makaopuhi lava lake, Hawaii

Abstract

The methods of rotation viscometry have been applied in the fieldto a tholeiitic lava at 1130 degrees to 1135 degrees C containingabout 25 percent crystals and 2 to 5 percent gas bubbles, using astainless steel spindle inserted through the lava crust. The resultsagree well with the Bingham model. Yield values in the lava are 1200and 700 dynes cm (super -2) , and the plastic constants are 6500and 7500 poises. Laboratory studies in silicone fluid show gas bubblesenhance plastic behavior. In general, lavas must be treated as non-Newtonianfluids; the conditions that may cause different types of fluid behaviorin tholeiitic lava are outlined.