GPS observations in Costa Rica from 1994-1997 reveal a complex pattern of motion consistent with the superposition of seismic cycle and secular plate margin deformation. In the south, velocity vectors are consistent with motion of the Panama Block plus postseismic deformation following the 1991 Limon earthquake, and interseismic strain due to partial locking of the Middle America Trench (MAT) t...

Although most models of thrusting assume that the hangingwall is actively displaced up thrust ramp while footwall remains passive, it has been suggested this could be an oversimplification and may also deform. Despite this, there are relatively few detailed investigations thrusts where deformed, perhaps reflecting issues with space accommodation if moves downwards to deeper levels. Furthermore,...

Pore pressure plays a key role in the generation of earthquakes subduction zones. However, quantitative constraints for its determination are quite limited. Here, we estimate subsurface pore by analyzing transient upwelling flow drilling mud from borehole C0023A International Ocean Discovery Program (IODP) Expedition 370, Nankai Trough off Cape Muroto. This upward provided first direct evidence...

The character of the incoming plate subducting at convergent margins and the processes affecting it as it passes below the shallow forearc may play a major role in the nature and extent of hazardous intraplate seismicity as well as the magnitude of volcanism and the chemistry of lavas produced in the overlying volcanic arc. The fate of incoming sediments and ocean crust and of their associated ...

[1] A >500-km-long east-west trending metamorphic belt in the Qiangtang terrane of central Tibet consists of tectonic melange that occurs in the footwalls of Late Triassic–Early Jurassic domal low-angle normal faults. The melange is comprised of a strongly deformed matrix of metasedimentary and mafic schists that encloses lesser-deformed blocks of metabasites, Carboniferous–Triassic metasedimen...

[1] Subduction zone plate boundary megathrust faults accommodate relative plate motions with spatially varying sliding behavior. The 2004 Sumatra-Andaman (Mw 9.2), 2010 Chile (Mw 8.8), and 2011 Tohoku (Mw 9.0) great earthquakes had similar depth variations in seismic wave radiation across their wide rupture zones – coherent teleseismic short-period radiation preferentially emanated from the dee...

The Legs Lake shear zone is a crustal-scale thrust fault system in the western Canadian Shield that juxtaposes high-pressure (1.0+ GPa) granulite facies rocks against shallow crustal (< 0.5 GPa) amphibolite facies rocks. Hangingwall decompression is characterized by breakdown of the peak assemblage Grt + Sil + Kfs + Pl + Qtz into the assemblage Grt + Crd + Bt ± Sil + Pl + Qtz. Similar felsic gr...