[1] Based on analysis of data from a trans-Mexico temporary broadband seismic network centered on Mexico City, we report that the subducting Cocos Plate beneath central Mexico is horizontal, and tectonically underplates the base of the crust for a distance of 250 km from the trench. It is decoupled from the crust by a very thin low viscosity zone. The plate plunges into the mantle near Mexico C...

Exhumation has been recognized as an important problem in tectonics and can be achieved by normal faulting, ductile thinning, and erosion. The exhumation of ultrahigh-pressure (UHP) rocks is the most challenging and least understood aspect of the exhumation problem. In this review, we focus on a variety of geologic settings with the goal of characterizing exhumation rates and maximum depths of ...

The junction of the Aleutian Island and the Kamchatka peninsula defines a sharp turn in the boundary of the Pacific and North American plates, terminating the subduction zones of the northwest Pacific. The regional pattern of shear-wave birefringence near the junction indicates that trench-parallel strain follows the seismogenic Benioff zone, but rotates to trench-normal beyond the slab edge. A...

We found that repeated slow slip events observed on the deeper interface of the northern Cascadia subduction zone, which were at first thought to be silent, have unique nonearthquake seismic signatures. Tremorlike seismic signals were found to correlate temporally and spatially with slip events identified from crustal motion data spanning the past 6 years. During the period between slips, tremo...

S U M M A R Y Receiver functions from teleseismic events, recorded by stations around the Gulf of California, are used to map the upper-mantle seismic discontinuities. We observe a mean transition zone thickness comparable to the global average for most of the region. A low-velocity layer is detected above the 410 discontinuity that varies in thickness along the Gulf of California. The 660 disc...

[1] Aseismic deformation transients can emerge as a natural outcome of the rate and state friction processes revealed in laboratory fault-sliding experiments. When that constitutive formulation is applied to model subduction earthquake sequences, transients can arise spontaneously for certain effective stress ( s) variations with depth. We show that if interstitial fluids are present and pore p...

Quantifying the precise thermal structure of subduction zones is essential for understanding the nature of metamorphic dehydration reactions, arc volcanism, and intermediate depth seismicity. High resolution twodimensional (2-D) models have shown that the rheology of the mantle wedge plays a critical role and establishes strong temperature gradients in the slab. The influence of threedimensiona...

We compute S-velocity profiles of the crust across the Messina strait (Italy), the tear zone at the southern end of the Ionian subduction zone. Separating Sicily from Calabria, the Messina Strait hosted some of the strongest earthquakes to ever occur in Italy. Here, the motion of the Ionian slab with respect to Sicily creates a complex tectonic setting characterized by lithospheric tearing. We ...