arXiv subjects

Jorge Jara

Publications and source records attributed to Jorge Jara.

2 recordsLinked to original sources

arXiv2024

Seismogenic Potential of the Subduction Zone in Northern Chile

The northern Chile region of the Nazca subduction zone ruptured in an Mw$\sim$8.5--9.0 earthquake in 1877, which induced a tsunami. The various magnitude estimates of this event are based on the evaluation of historical records, seismic intensities, and/or tide gauge information; however, its actual along-strike extent is debated. Based on geodetic data, the previous studies have suggested that this region has the potential for an Mw8.2--8.8 event. We re-evaluate the seismic potential of the region, accounting for the buildup rate of moment deficit along the megathrust, the earthquake magnitude--frequency distribution, and the physics of earthquakes. We combine an improved probabilistic estimate of moment deficit rate with results from dynamic models of the earthquake cycle, testing, in particular, the influence of a potential aseismic barrier near the city of Iquique, which may influence the extent and magnitude of large events in this region. We find that Mw8.8 is the most probable maximum magnitude earthquake in the region, and that the potential barrier likely has a limited impact considering uncertainties. We discuss the effect of the moment deficit rate on the fault, the b-value, and the importance of postseismic processes on our results.

physics.geo-ph↗

arXiv2021

Signature of transition to supershear rupture speed in coseismic off-fault damage zone

Most earthquake ruptures propagate at speeds below the shear wave velocity within the crust, but in some rare cases, ruptures reach supershear speeds. The physics underlying the transition of natural subshear earthquakes to supershear ones is currently not fully understood. Most observational studies of supershear earthquakes have focused on determining which fault segments sustain fully-grown supershear ruptures. Experimentally cross-validated numerical models have identified some of the key ingredients required to trigger a transition to supershear speed. However, the conditions for such a transition in nature are still unclear, including the precise location of this transition. In this work, we provide theoretical and numerical insights to identify the precise location of such a transition in nature. We use fracture mechanics arguments with multiple numerical models to identify the signature of supershear transition in coseismic off-fault damage. We then cross-validate this signature with high-resolution observations of fault zone width and early aftershock distributions. We confirm that the location of the transition from subshear to supershear speed is characterized by a decrease in the width of the coseismic off-fault damage zone. We thus help refine the precise location of such a transition for natural supershear earthquakes.

physics.geo-ph↗