PerspectiveGeophysics

Dangers of Being Thin and Weak

Science  06 Dec 2013:
Vol. 342, Issue 6163, pp. 1178-1180
DOI: 10.1126/science.1246518

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Summary

Why did the plate boundary fault at the Japan Trench slip tens of meters to generate a devastating tsunami in the Tohoku–Oki earthquake on 11 March 2011? Does the large slip in the shallow part of the fault represent a common process in subduction zones, or does it reflect site-specific geological conditions? Using the scientific drilling vessel Chikyu and working at the limit of drilling technology, researchers of the Japan Trench Fast Drilling Project (JFAST) have retrieved rock samples and made measurements in the culprit fault zone to seek answers. Their findings are reported in three papers in this issue. Based on different types of observations, Chester et al. on page 1208 (1), Fulton et al. on page 1214 (2), and Ujiie et al. on page 1211 (3) show that an important reason for the large slip is that the shallow fault zone is thin and weak.