Abstract:
THE MASSIVE MAUNA LOA LAVA FLOW OF JUNE 1950 BURIED ABOUT A MILE OF THE MAINBELT HIGHWAY ON HAWAII TO DEPTHS UP TO 60 FT. THE INITIAL TEMPERATURE OF THE LAVA WAS 950 C. HEAT LOSS BY THERMAL RADIATION FROM THE SURFACE WAS OF IMPORTANCE ONLY DURING THE INITIAL PERIOD OF A FEW WEEKS. THEREAFTER THE RATE OF COOLING BECAME DEPENDENT ON THE RATE OF HEAT CONDUCTION FROM THE INTERIOR TO THE SURFACE. COMPUTATIONS OF TEMPERATURES AT DIFFERENT DEPTHS FOR VARIOUS PERIODS OF COOLING FROM 1/2 YEAR TO 5 YEARS WERE MADE BY THE THEORY OF HEAT CONDUCTION. RISING HOT GASES TEND TO EQUALIZE THE TEMPERATURE WITHIN A CRACK TO ABOUT THE TEMPERATURE OF THE LAVA AT THE DEPTH TO WHICH THE CRACK EXTENDS. ON THIS BASIS, THE HOTTER CRACKS WITH THE TEMPERATURES OF 700 F ARE BELIEVED TO EXTEND DOWN TO A DEPTH SOMEWHERE BETWEEN 6 1/4 AND 12 1/2 FT. IN ORDER TO EXPEDITE THE WORK OF RECONSTRUCTION, IT SEEMS BEST TO DEPEND PRIMARILY ON BORROW MATERIAL FOR GRADING OPERATIONS, LIMITING EXCAVATIONS TO A MAXIMUM OF APPROXIMATELY 6 FT. FOR SUCH SHALLOW CUTS, THE TOP HALF PROBABLY CAN BE MOVED BY BLADING WITH A BULLDOZER (BECAUSE OF THE FRAGMENTAL NATURE OF THE SURFACE) AND THE BALANCE LOOSENED BY MUD-CAPPING. /AUTHOR/
Supplemental Notes:
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