Volcanologist.
a marine vulcanologist
A Botanist
A paleontologist would generally study paleontology.
The type of investigation would be fieldwork.
Oceanogarphers study the oceans geography, but there are many other types of jobs that study things such as fish and volcanoes under the waves.
meteorologist
geologists
A geologist studies natural hazards such as volcanoes and earthquakes.
a physicist
Geologist - specifically a 'Vulcanologist'
biologist means who study about life and a scientist who study about every thing
zoologists