The International Space Station's orbit took it directly over Matua Island northeast of Japan just after the central volcano erupted. There had been clouds over the site, but the initial explosion blew a circular hole in the cloud deck allowing a view of the ground. The plume rose straight through the hole, and water vapor that was forced upward cooled forming a new cloud at the top of the plume.
Credit: NASA/JSC Gateway to Astronaut Photography of Earth