Plate boundaries are constantly shifting and moving land causing friction. This firction can shake the ground causing devastating damage to civilizations around the world.
Earthquakes
Earthquakes occur all the time around the world. Most of them are small and undetectable, but every once in a while tension will build between two plates at their boundary and when that tension breaks it releases a massive amount of enrgy causing an earthquake.
Both of the images above were taken from the 1989 earthquake in San Francisco. The quake killed 52 people, and caused an estimated 6 billion dollars worth of damage.
Tsunamis
Tsunamis can occur when large amounts of water are displaced by the shaking of an earthquake. When the water displace it creates a wave short in heaight as it travels across the open ocean. When it approaches land it will swell into a big wave, but it is better described as a sudden rise in sea level.
Tsunami Damage
The devastation seen above is the damge from the 2004 Indian Ocean Earthquake. The earthquake created a tsunami which killed just under just under 187,000 people and 43,000 people and 43,000 people missing.
Volconoes
Volcanoes can be found at convergent, and divergent plate boundaries. When volcanoes erupt it will have different effects on the land around it depending on what type of volcano it is. Some damage may occur from magama flows, flying debris, hot ash, or lahars (a flow of water saturated debris flowing down the slope of the mountain.
A picture of Mt. St. Helens in Washington before its first eruption, and during one of its recent eruptions.