We just had an earthquake swarm along the subduction zone trench offshore of the Solomon Islands. Here is the USGS earthquake page for this Mw 6.8 subduction zone earthquake.
This map shows the modeled shaking intensity for this earthquake. Bouganville Island likely experienced MMI IvV. From the USGS page, “Felt indoors by many, outdoors by few during the day. At night, some awakened. Dishes, windows, doors disturbed; walls make cracking sound. Sensation like heavy truck striking building. Standing motor cars rocked noticeably.”
This map shows the slab contours (an estimate of the subduction zone plate interface). These contours are estimated by Hayes et al., (2012).
This region has been active in the past couple of years. There have been compressional, extensional, and transform earthquakes since 7/7/2013. This map shows the earthquake epicenters (blue dots), their moment tensors, magnitudes and date of rupture. Here is my page regarding the earthquakes from April 2014. This is the USGS tectonic poster for the region that I used as a background. I placed black arrows to show the relative plate motion across the tectonic plate boundaries adjacent to these earthquakes.
Here is a primer for those who would like to understand focal mechanisms better (from the USGS). Normal earthquakes are extensional, reverse earthquakes are compressional, and strike-slip earthquakes are the result of shear.
- Baldwin, S.L., Fitzgerald, P.G., and Webb, L.E., 2012, Tectonics of the New Guinea Region, Annu. Rev. Earth Planet. Sci., v. 40, pp. 495-520.
- Hayes, G. P., D. J. Wald, and R. L. Johnson (2012), Slab1.0: A three-dimensional model of global subduction zone geometries, J. Geophys. Res., 117, B01302, doi:10.1029/2011JB008524.
- Tregoning, P., McQueen, H., Lambeck, K., Jackson, R. Little, T., Saunders, S., and Rosa, R., 2000. Present-day crustal motion in Papua New Guinea, Earth Planets and Space, v. 52, pp. 727-730.