# The frequency of large [[earthquakes]] (more than 6.99 on the Richter scale) doubles roughly every 40 years,<ref>http://www.earth.webecs.co.uk/</ref> rendering long-term stability impossible. Large earthquakes have increased by more than 20% in only the last decade.<ref>http://earthquake.usgs.gov/earthquakes/eqarchives/year/eqstats.php</ref> | # The frequency of large [[earthquakes]] (more than 6.99 on the Richter scale) doubles roughly every 40 years,<ref>http://www.earth.webecs.co.uk/</ref> rendering long-term stability impossible. Large earthquakes have increased by more than 20% in only the last decade.<ref>http://earthquake.usgs.gov/earthquakes/eqarchives/year/eqstats.php</ref> |