Very powerful yet in an area without any earthquake risk. Clearly a single blast, as seen in seismometers. Not very deep (10 km). Replicas : simply a succession of less powerful blasts to imitate natural replicas. All countries are able to dig to these depths since long ago : see Kola Superdeep Borehole.
The CTBTO neglects signals that look clearly like nuclear explosions because they are “too deep” but they actually are nuclear tests. Some countries seem to use their volcanic areas because “tornillo” events look like underground nuclear detonations, yet this area in Italy is very far from a volcanic area, it’s an alluvion zone. A quake of 6 on the Richter scale should kill much more than 6 persons. But without S waves it is not deadly. One can look on the EMSC-CSEM website to see this. For instance :
and one “replica” :
A comparison with a normal quake, below ! Here you have a normal P/S ratio.
There are many cases like that (10 to 20 km deep, hugely dominated by P waves, not explained by volcanism) elsewhere in the world. See for instance other cases : Iran, Russia, China. (China seems a very test-prone country) In principle you should have more or less 60% S, 40% P. Of course these are not the sole countries but these links include causality of major fission products leaks which do not seem to happen when other countries do tests. The Italian case is specific in that 6 persons were killed. Their families have the right to know the truth.
Ferrara, nearby, has been striken by a quake due to soil liquefaction in 1570. The initial quake was less powerful (5.6 vs. 6.1 in 2012, which is a significant difference) yet the replicas lasted for months, even years, whereas seismic activity disappeared totally very quickly (in a few weeks) in 2012. A soil liquefaction earthquake would have had replicas during a much longer period, as in 1570.
On why I don’t campaign against nuclear bombs (only against depleted uranium use in warheads), see : https://depleteduranium.org/2017/08/06/why-we-dont-campaign-to-ban-the-bomb-pourquoi-ne-pas-demander-linterdiction-des-armes-nucleaires-tactiques-et-strategiques/