Hi look at the bottom of this page which lists some of the benefits http://revisionworld.com/gcse-revision/geography/tectonic-activity/volcanoes

Years after the eruption the lava flow from the volcano can fertilise soil, another advantage is you can start using geothermal energy and maybe hot springs or geysers are created e.g.yellow-stone national park, this can be a tourist destination/ attraction

Hope that helped :)