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The University of Southampton
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Ocean and Earth Science, National Oceanography Centre Southampton

Research project: Active-source seismic refraction across the Sumatra subduction zone

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Historic earthquakes have ruptured distinct segments of the plate boundary megathrust at the Sumatra subduction zone. We use seismic refraction data to derive a velocity model for a  3-D area crossing the plate boundary near Nias and Siberut (Fig. 1). Seismic refraction datasets can shed light on factors controlling rupture segmentation [e.g., Tang et al., 2013].

Objectives

  • Determine the structure and velocities across the areas that ruptured in the 2005 Mw 8.7, 1935 Mw 7.7, and 1797 Mw ~8.7-8.9 earthquakes.
  • Compare velocity structure from different rupture segments and in the transition zones between them.
  • Test hypotheses regarding the causes and processes of segmentation and rupture of megathrusts.
Figure 2
Figure 2
Figure 1
Figure 1

3-D seismic refraction data

3-D refraction data were recorded in 2008 from Nias to Siberut on 47 ocean-bottom seismometers (OBS) using an air gun source (Fig. 2). The area covered was approx. 300 km by 200 km, and 8,400 air-gun shots were fired along the profiles. P-wave first arrival refractions were picked from the OBS data and will be inverted to give a velocity model.

Key Contacts

Prof. Timothy Henstock

Prof. Lisa McNeill

Prof. Jonathan Bull

Dr. Marianne Karplus

PhDs and Other Opportunities

Please visit GSNOCS

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