What are the causes and effects of earthquakes and volcanic eruptions?

For info, readings, videos and ideas on the causes and effects of earthquakes:
The geography site, explains tectonic earthquake and volcanic earthquake.
Earthquake effects covering 'shaking, landslides, liquefaction, and tsunamis'.
Youtube National Geographic.

For info, readings, videos and ideas on the causes and effects of volcanic eruptions:
Volcano world, showing current volcanic eruptions.
Youtube explanation.

For both:
Global change, with clickable maps to check where both earthquakes and volcanos are happening; the Mercalli intensity earthquake scale; and information on melt points of solid rock material.
Slideshare on living with earthquakes and volcanoes (remove the ad and click the up/down buttons to see the slideshow).

There is an overwhelming ton of stuff on earthquakes and volcanoes on the Internet. Find something you never knew before!