I love living in California, but I am always waiting for the next 'big one'.
The app, NewsQuakes, will not predict this, but it will show you the latest quakes in your area. You can see earthquakes that have happened in past day, hour or week. You can see these listed in detail or by push pins on a map. It also includes volcano alerts from around the world.
It has a wealth of interesting video and audio clips from USGS, along with a calendar of upcoming lectures on related subjects in California.
The interface of this app is very smooth and appealing. It works on both the iPhone and the iPad. The iPad app is a full screen version.
For just 99 cents, it is definitely worth adding to your collection.