The pumice raft-forming 2012 Havre submarine eruption was effusive

- Havre magma entered the ocean before fragmenting.
- Clasts were produced by quenching buoyant magma in the ocean.
- Buoyant >1 m diameter pumice blocks floated to the ocean surface.
- Clasts with enough isolated porosity and trapped gas floated in a raft while the rest sank.