Katla under the glacier Mýrdalsjökull is an active volcano in the southern part of the Icelandic Highland. “Active” in a geological sense is measured in tens and hundred of years of an interval between eruptions. In the past, Katla has had the habit of erupting at least once-twice every century and has erupted twenty times since the Icelandic settlement in the tenth century. It has been a long time since the interval was as long as the current one. That is why Katla is monitored by the Icelandic Met Office and geologists around the clock all year round.