Active tectonics

Crustal earthquakes and the seismic cycle

I am interested in the use of InSAR to study active crustal deformation produced by both tectonic and volcano-tectonic processes. Geodetic data can provides critical information not available by point source seismic inversions like the complexity of fault slip in the Earth’s surface, evidence for complex rupture geometries and the role of magmatic fluids in aseismic deformation. InSAR also provides insights on large scale mechanisms of deformation across orogens.

Interferograms that span the seismic cyle of the Pichilemu fault (black lines) in Central Chile. This fault ruptured in two Mw 7.0 eqarthquakes triggered by the Mw 8.8 Maule megathrust earthquake in 2010. Thr first interferogram shows no interseismic strain accumulation three years before the earthquake, the second and third interferograms show the coseismic rupture imaged by L-band ALOS and C-band ENVISAT data, and the last two interferograms show stress-driven afterslip triggered by the coseismic rupture during a time span of 3 months.

Relevant publications

Fully joint inversion of the 2016 Mw 7.6 Chiloé earthquake.
Bravo, F., Peyrat, S., Delgado, F., Fuentes, M., Derode, B., Pérez, A., Campos, J., Geophysical Journal International, 2022, ggac411, doi:10.1093/gji/ggac411

Volcano-tectonic interactions at Sabancaya volcano, Peru: eruptions, magmatic inflation, moderate earthquakes, and fault creep
MacQueen, P., Delgado, F., Reath, K., Pritchard, M., Lundgren, P., Milillo, P., Bagnardi, M., Macedo, O., Aguilar, V., Lazarte, I., Machacca, R., Miranda, R. Journal of Geophysical Research. 2020, doi.org/10.1029/2019JB019281. Special issue on Creep on continental faults and subduction zones: Geophysics, geology, and mechanics.

Deformation and seismicity near Sabancaya volcano, southern Peru, from 2002 to 2015
Jay, J.A., Delgado, F.J., Torres, J.L., Pritchard, M.E., Macedo, O., Aguilar , V. Geophys. Res. Lett.. 2015, 42, 2780–2788. doi: 10.1002/2015GL063589.

Volcano-tectonic interactions

TerraSAR-X wrapped (a) and unwrapped (b) interferogram of the July 17 2013 Mw 5.8 earthquake NW of Sabancaya volcano (black triangle) in Southern Peru. InSAR shows that the earthquake is of tectonic origin, a curved normal fault with a strike slip component. These details, like the non-planar fault, cannot be inferred by point source models such as those calculated by global earthquake networks like from USGS or GCMT, highlighting the value of having high spatial resolution measurements of ground deformation. The geodetic focal mechanism is in agreement with the seismic moment tensor for both the geometry and the seismic moment, and shows that there is no evidence for either volcano-induced deformation or magma injection. The interferogram also shows triggered slip on smaller faults N of Sabancaya, as well as residual atmospheric noise. Wrapped (c) and unwrapped (d) and 2013/11 - 2016/12 TerraSAR-X mean velocity calculated from InSAR time series that show ~4-5 cm of uplift produced by a deep inflating source beneath Hualca Hualca volcano. The inflation likely triggers aseismic afterslip in the fault responsible for the July 2013 Mw 5.9 earthquake, which is better observed in the wrapped interferogram.

Francisco Delgado

Active tectonics

Crustal earthquakes and the seismic cycle

Relevant publications

Volcano-tectonic interactions

Relevant publications