Cali has Volcanos too. Mt. Shasta and Mt. Lassen are the main two but there are numerous Cinder Cones in the southern Cascades of Northern California. The only Volcanic area I am aware of in the Sierras is Mammoth Mountain and the Long Valley Super Caldera area.There are actually 4 plates that meet at Japan.
Most volcanoes just ooze, some just steam a little. Explosions like Mt. St. Helens are much less common.
The link I posted is really cool and real time so it updates. When you zoom in or out or move the map the list of quakes in the left column will just list those in the screen area. Another interesting thing is that most but not all quakes are along the edges of the major plates. The others are on fault lines like the New Madrid fault. I wonder if those that aren't along plates and faults like those that are in Oklahoma may be from gas fracking.
Another thing that will help you are these links. Ring of fire is so interesting.
http://vulcan.wr.usgs.gov/Glossary/PlateTectonics/Maps/map_plate_tectonics_world.html
http://fionamariecarter.wordpress.com/2011/04/27/5es-explore-plate-tectonics/
http://www.learner.org/interactives/dynamicearth/plate.html
This is a very cool site.
http://blogs.discovermagazine.com/imageo/
One of the stories tells of a 68 million metric ton February landslide in Alaska that was the largest on earth since 2010.
One of the things I love about Costa Rica is it's so active geologically. It's only the size of West Virginia but has 6 active volcanos and 61 inactive or extinct ones. It's along the ring of fire so geologically it is changing rapidly. Two of the active volcanos, Irazú and Poás, you can drive right up to the craters. Three others you can hike to. The summit of it's most famous, Arenal, is closed to tourists because of the danger but it's been quiet for 4 years.
When I was at Arenal you could see the lava flow at night and rocks blown out during the day from an adjacent mountain.
On a clear day (very rare there), from the rim of Irazú you can see both the Atlantic and Pacific from the same spot. Poás erupted a couple times just last month.
http://www.volcanodiscovery.com/costa_rica.html
The smallest Mountain range in the World is not far from Ron's house.
The Sutter Buttes is a extinct volcano that erupted and weathered down long ago to become the smallest range in the world.