Here is the pulse of heat from a ětypicalî earthquake. The X axis is time after the earthquake in hours and the y axis is the temperature increase above the background value in degrees C.
The most striking aspect of this plot is that in order to see a heat pulse with a large temperature spike, you need to be extremely close to the fault, which means you need to have a very narrow fault zone. Our samples come from a fault with an ultracataclasite zone 5 cm wide, so we can get to within 2.5 cm of the center of the fault zone.
Not only is the length scale a lot shorter than you might expect, but you can also notice how transient the temperature pulse is -- the significant temperature increase occurs in the first hour after the earthquake. You may remember that fission tracks can anneal in as little as 20 minutes, so we should be able to observe this pulse if the magnitude of the pulse is high enough.
