Just Say No to Abuse Declaring War on Terrorism. They are generally found in places where there are heated rocks quite close to the surface.
Geysers are rare.
The problem is the special plumbing. Most geysers are found in the volcanic rock rhyolite, a high silica rock. Fields of rhyolite are rare hence geysers are rare. The site goes on to give a readable explanation of what happens before and during an eruption. There are pictures of six basic type of plumbing systems that a geyser might have.