Abandoned Coal Mines
This site is a fairly complete mine list for Eastern Ohio and Western Pennsylvania counties.
EM-DAT: The International Disaster Database
This World Health Organization site lists natural and technological disasters all over the world from 1909 to the present.
National Oceanographic Data Center (NODC)
Everything you ever wanted to know about the oceans has been gathered on this data-rich site.
Ohio Geological Survey
Find out everything about Ohio geology at this site, which offers data, interactive maps and event calendars.
USGS Geology Division
Offers historical and real-time information on earthquakes, volcanic eruptions, landslides and other geology topics.