Watching the San Andreas

Yesterday's M4.8 earthquake by the Salton Sea in southern California [right, USGS] following a series of smaller events in the previous week, has seismologists wondering if this could be a foreshock for something larger.

[below, Mohawk Valley (113A) seismometer records aftershocks of yesterday's M4.8 event on the southern San Andreas fault, including a M3.6 event at 07:51 UTC]

The series of recent small earthquakes are on the southern tip of the San Andreas fault, suggesting that a larger event would rupture from south to north, with the energy focused into southern California. We expect a north to south rupture would send more energy across Arizona.