MVO Researches Cooling of Pyroclastic Deposits
Drs. Henry Odbert and Adam Stinton are currently working on an ongoing research project to study the cooling of pyroclastic deposits in order to estimate how long they take to cool to ambient temperatures. They have found that the top surface of pyroclastic deposits cools within weeks, but that the inside can remain hot for a long period of time. This is important because hot pyroclastic deposits can be hazardous, with the potential to seriously burn or even cause small explosions when it comes into contact with water.
Temperatures at the top of pyroclastic deposits can be measured with a thermometer or remotely using a thermal infrared camera. Temperatures on the inside of deposits are not so easy to measure. In order to do so, a deep hole must be dug in order to access deep into the deposit – a process that can involve considerable work. Pictured below is a team of MVO scientists, staff, and volunteers recently digging such a trench at Trants in pyroclastic deposits from the 11 February 2010 dome collapse. Measurements from this excursion show that the deposits are still hot with a temperature of 125 C at a depth of 3 m (the deposit is approximately 12 m thick in this area). Temperature measurements have been made a number of times since the deposits were emplaced. Analyzing these measurements using a thermal conduction computer model suggests that it will take many years for the core of the deposit to reach ambient temperatures.
