Sorcery is the direct casting of a spell.
A miracle - the form of Divine Intervention used by sorcery orders - is achieved through appealing to a saint. On this kind of scale, sorcery itself would be ineffective and a direct appeal to a saint for a miracle would also be a tough call. I therefore suspect that the Jrusteli HeroQuested for a miracle.
I'd also be careful about trying to completely apply the RQII DI mechanics (which cover miracles, BTW, and how they differ to divine cult/Pact-based intervention) to a large-scale magical event like this. Resurrecting a large number of people would almost certainly require a combination of HeroQuesting and petitioning a saint for a miracle. It might even have gone something like this:
Jrusteli Provincial Governor: 'Aieee! The bastard Waertagi have drowned an entire city! I need those shipwrights. The navy needs those shipwrights. High Priest, what say you?'
High Priest of True Malkioni Church: 'I'll have a look in the Book... Okay. The 98th canto of Chapter 4,318 says: And lo, the living who serve me and those closest to me shall have remission over the state of Death, for that Erasanchula defied me and I hereby grant permission to my most blessed followers to defy the Erasanchula called Death, for that is its name.'
Jrusteli Provincial Governor: 'What the bloody hell does that mean, then?'
High Priest: 'Well, clearly the most blessed followers are the saints - unless, my lord, you are presuming to be closer to Malkion than say, I, or Saint Xemela...'
Provincial Governor: 'Don't be so bloody stupid. What do you think I am? One of those Loskalmi Hrestoli heretic gits?'
High Priest: 'Of course not, my lord. In that case, the most blessed followers are clearly the saints themselves. Since we need to defy the dominion of Death, we must turn to her most virtuous Lady of Healing, Saint Xemela. I have taken the liberty of reading the Book of Eternal Succour nd Respite which relates her earthly deeds....'
Governor: 'And...?'
High Priest: 'And there is clearly a myth herein where Saint Xemela brought back from the dead the plague victims of Arolanit, defying Death and Malia.'
Governor: 'Ah, so its a HeroQuest eh? Right, summon the Otherworld Explorers...'
High Priest: 'Um, not quite, my lord. Saint Xemela's efforts were considerable for she absorbed the plague into her own being. One would need to petition her on the Saint's Plane and show devotion through a HeroQuest - perhaps a HeroQuest that alleviated her of the sorrow she incurred through resurrecting the plague victims?'
Governor: 'So what you're saying is...'
High Priest: 'Precisely my lord. You are most astute. We need a great deal of praying and a mighty HeroQuest.'
Governor: 'Make it so, priest.'
High Priest: 'I have already written the sermon, prepared the prayers and called for several waertagi sacrifices.'
Governor: 'Brilliant. I'll get the Otherworld Explorers...'
