Too early to speculate on the eruption phases.
EM results should give the first view of the geological structures below. You can think of EM as an interpretation but nothing beats drilling in regards to certainty of structure. It is a large kimberlite so the key is to take samples from as many different areas as possible which they will do with the outer rim sampling.
Also keep an eye on the multi-purpose drill rig they ordered.
If it has wide-core capability, that is a big bonus. Wide-core capability means they can also take samples from the central areas of the kimberlite as well where the Pyroclastic Kimberlite (PK) sits deeper.
Wide-core capability means they can attack the kimberlite on 2 fronts.
They can use excavators to bulk sample the shallower areas at the outer rim. And they can use wide-core drilling to sample from the deeper central zone of the kimberlite.
