California straddles the boundary between two of the Earth's tectonic plates. As a result, it is broken by numerous earthquake faults. Taking into account the earthquake histories and relative rates of motion on these many faults, the Uniform California Earthquake Rupture Forecast (UCERF) study concludes that there is a probability of more than 99% that in the next 30 years Californians will experience one or more magnitude 6.7 or greater quakes, potentially capable of causing extensive damage and loss of life. This book provides an overview of the implications, risk, detection, warning and research into a major earthquake in California within the next 30 years.