The 2007 Mw 7.7 Tocopilla Earthquake

The 2007 Mw 7.7 Tocopilla earthquake was the first large (M>7) earthquake occurring inside the seismic gap left behind by the 1877 M~9 earthquake. It caused two casualties and significant damage to the coastal communities north of Antofagasta. It was also the first large earthquake recorded by the newly installed IPOC observatory. The event ruptured an approximately 130 km piece of the deepest part (approx. 30-55 km depth) of the seismogenic plate interface [Motagh et al., 2010; Peyrat et al., 2010; Schurr et al., 2012]; a region though to be characterized by specific frictional properties [Béjar-Pizarro et al., 2013; Schurr et al., 2012]. The shallower, unbroken part of the plate interface poses still a significant seismic hazard.

The Task Force Earthquake of the GFZ German Research Centre for Geosciences installed a dense temporary seismic network to record aftershocks following the event [Fuenzalida et al., 2013]. Approximately one month after the mainshock, a large aftershock broke vertically through the subducted oceanic plate [Fuenzalida et al., 2013; Ruiz and Madariaga, 2011]. The data is archived at the GFZ Seismological Data Archive (GEOFON) with the network code Y3.

The central South American subduction zone and the IPOC seismic network. Red squares indicate sites of broadband/strong motion seismographs that were operating at the time of the 2007 Tocopilla earthquake. Filled circles show background seismicity from 01/01/1970–13/11/2007 colored according to depth. Historical earthquake rupture regions are sketched as ellipses. MP – Mejillones Peninsula. Figure modified from Schurr et al. [2012].

References

Béjar-Pizarro, M., A. Socquet, R. Armijo, D. Carrizo, J. Genrich, and M. Simons (2013), Andean structural control on interseismic coupling in the North Chile subduction zone, Nature Geoscience, 6(6), 462-467, doi.org/10.1038/ngeo1802

Fuenzalida, A., B. Schurr, M. Lancieri, M. Sobiesiak, and R. Madariaga (2013), High-resolution relocation and mechanism of aftershocks of the 2007 Tocopilla (Chile) earthquake, Geophysical Journal International, 194(2), 1216-1228, doi.org/10.1093/gji/ggt163

Motagh, M., B. Schurr, J. Anderssohn, B. Cailleau, T. R. Walter, R. Wang, and J.-P. Villotte (2010), Subduction earthquake deformation associated with 14 November 2007, Mw 7.8 Tocopilla earthquake in Chile: Results from InSAR and aftershocks, Tectonophysics, 490(1-2), 60-68, doi.org/10.1016/j.tecto.2010.04.033

Peyrat, S., R. Madariaga, E. Buforn, J. Campos, G. Asch, and J. P. Vilotte (2010), Kinematic rupture process of the 2007 Tocopilla earthquake and its main aftershocks from teleseismic and strong-motion data, Geophysical Journal International, 182(3), 1411-1430, doi.org/10.1111/j.1365-246X.2010.04685.x

Ruiz, S., and R. Madariaga (2011), Determination of the friction law parameters of the Mw 6.7 Michilla earthquake in northern Chile by dynamic inversion, Geophysical Research Letters, 38(9), n/a-n/a, doi.org/10.1029/2011gl047147

Schurr, B., G. Asch, M. Rosenau, R. Wang, O. Oncken, S. Barrientos, P. Salazar, and J. P. Vilotte (2012), The 2007 M7.7 Tocopilla northern Chile earthquake sequence: Implications for along-strike and downdip rupture segmentation and megathrust frictional behavior, Journal of Geophysical Research: Solid Earth, 117(B5), n/a-n/a, doi.org/10.1029/2011jb009030