Earthquake along the New Britain trench (Solomon Isles and Papua New Guinea)

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.

Here is a map of the region with the recent swarm.

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.

This map shows the general plate boundaries on the region (Tregoning et al., 2000).

This map shows the relative age of these oceanic plates of the region (Baldwin et al., 2012).

This map shows plate velocities and euler poles for different blocks. Note the counterclockwise motion of the plate that underlies the Solomon Sea (Baldwin et al., 2012).

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.

References:

  • 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.
Category(s): College Redwoods, earthquake, education, Extension, geology, plate tectonics, subduction, Transform

5 Responses in other blogs/articles

  1. […] July and August of 2010. Further to the southeast, there was a flurry of seismic activity in 2014. Here is a page I put together about that swarm. There were some other earthquakes even further to the south that I […]

  2. […] July and August of 2010. Further to the southeast, there was a flurry of seismic activity in 2014. Here is a page I put together about that 2014 swarm. There were some other earthquakes even further to the south […]

  3. […] 2014/12/06 nearby to the east, not New Britain […]

  4. […] 2014.12.06 M 6.8 […]

  5. […] posted about the tectonics of this region during some earthquakes from 2014/12/06. For that post, I found a generalized tectonic map of the region from Baldwin et al. […]

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