The recent events that shook a relatively remote part of the Mojave Desert region of Eastern California provide an acute reminder of the major risk posed by earthquakes in the state. It has been a while now since California experienced a large earthquake, and the main event in this sequence – with a magnitude of Mw7.1, was the most powerful earthquake to occur in the state in twenty years.
Since then, the field of seismology as well as earth scientific measuring capabilities have undergone quite substantial improvements and innovations. Immediately after the start of the sequence, several coordinated efforts from academic, government and engineering organizations resulted in focused field surveys and the installation of additional, more densely spaced instrumentation to monitor seismicity and surface deformation, in and around the epicentral area.
So far, extraordinary amounts of high-quality data have been collected that will undoubtedly provide new insights and understanding of earthquakes in general and earthquake hazard and risk in (Southern) California, in particular. Work on these new data sets has only just started, but what have we learned so far? Here is a summary of observations and interpretations based on various (preliminary) field surveys, reports and briefings.