> The total energy created by a PBH roughly equals the energy produced by the detonation of one tonne of TNT, but this energy is the total energy it deposits along its path through the Earths diameter, not the energy it produces on impact. So don’t expect a magnificent explosion, we’d be lucky to see a spark as it hits the ground.
It looks at pairs of seismic events that trace line through the earth and are timed correctly.
> Two sets of reports were found in the 1993 database that fit all the criteria for a linear source. The model and residuals (observed minus predicted arrival times) for the first event are given in Table 1. The RMS residual is 0.73 sec. This RMS value would indicate a good fit for a well-located earthquake.
A physics stack exchange answer about it: https://physics.stackexchange.com/a/55184
The most relevant part:
> The total energy created by a PBH roughly equals the energy produced by the detonation of one tonne of TNT, but this energy is the total energy it deposits along its path through the Earths diameter, not the energy it produces on impact. So don’t expect a magnificent explosion, we’d be lucky to see a spark as it hits the ground.