Abstract
I use template matching and precise relative relocation techniques to develop a high-resolution earthquake catalog for the initial portion of the 2019 Ridgecrest earthquake sequence, from 4 to 16 July, encompassing the foreshock sequence and the first 10+ days of aftershocks following the Mw 7.1 mainshock. Using 13,525 routinely cataloged events as waveform templates, I detect and precisely locate a total of 34,091 events. Precisely located earthquakes reveal numerous crosscutting fault structures with dominantly perpendicular southwest and northwest strikes. Foreshocks of the Mw 6.4 event appear to align on a northwest-striking fault. Aftershocks of the Mw 6.4 event suggest that it further ruptured this northwest-striking fault, as well as the southwest-striking fault where surface rupture was observed. Finally, aftershocks of the Mw 7.1 show a highly complex distribution, illuminating a primary northwest-striking fault zone consistent with surface rupture but also numerous crosscutting southwest-striking faults. Aftershock relocations suggest that the Mw 7.1 event ruptured adjacent to the previous northwest-striking rupture of the Mw 6.4, perhaps activating a subparallel structure southwest of the earlier rupture. Both the northwest and southeast rupture termini of the Mw 7.1 rupture exhibited multiple fault branching, with particularly high rates of aftershocks and multiple fault orientations in the dilatational quadrant northeast of the northwest rupture terminus.
High-resolution multibeam bathymetry of the northern Mid-Atlantic Ridge at 45–46° N: the Moytirra hydrothermal field
