The Hertfordshire Oil Storage Terminal explosion and fire has doubtless dominated news in the UK and Europe, though in all honesty it hasn’t gotten major play here in the US. Doubtless that’ll change if it’s found to be a terrorist attack and not an accident, but that’s not actually my point. It occurred to me that this is a relatively high-yield detonation, and I have the means to chart its effects in a basic way.
So, based on the seismic report of a 2.4 magnitude event, I’ve estimated the yield at about four metric tons of TNT (as per the chart found on the Wikipedia‘s Richter scale article, as well as other sources). As you can see on the chart, that gives figures consistent with initial damage reports: the 0.25psi ring extends out to 1.02 kilometers (0.64 miles), which is about where you’d stop seeing widespread window shattering and door displacement.
Remember that the distances shown don’t define the distance out to which a human would be able to feel a blast, and certainly don’t say anything about the distance at which a blast could be heard. And also remember that I’m making a rough estimate of yield based on an initial estimate of the explosion’s seismic magnitude, not to mention I just made a guess as to the exact epicenter.
Still, it’s interesting to be able to chart the event like this. To me, anyway.