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Seismically Induced Erosion and the Mass Balance of a Large Earthquake

Hovius, N.; Meunier, P.; Lin, C.; Dadson, S.J.; Chen, H.; Horng, M.J.. 2008 Seismically Induced Erosion and the Mass Balance of a Large Earthquake. Eos, Transactions, American Geophysical Union, 89(53), H43F-1083.

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Abstract/Summary

Earthquakes create topographic relief by opposite displacements of the Earth's surface on either side of a fault. Over a seismic cycle most energy is released in large earthquakes, and they are thought to be the principal cause of relief formation in tectonically active areas. But the topographic effect of earthquakes is reduced by seismically induced erosion. Earthquakes trigger slope failure, often in proportion to their strength, and increase substrate erodibility through shattering of rock mass and coalescence of cracks. Intense mass wasting has been reported from the epicenters of many large earthquakes, and a link between earthquakes and increased fluvial sediment transport has been demonstrated. After an earthquake, enhanced erosion persists, and its intensity and decay determine the net topographic effect of the earthquake. We have calculated the mass balance and topographic effect of the MW7.6 Chi-Chi earthquake in west Taiwan. Rates of mass wasting in the Chi-Chi epicentral area increased fivefold due to the earthquake, and have decayed since then to background values. The sediment concentration in the epicentral Choshui River has closely tracked hillslope mass wasting, and from the excess sediment load of typhoon floods following the earthquake, we estimate that about half of the co- and post seismic surface elevation has been removed by seismically-induced erosion. Further erosion at background rates will annul the remaining earthquake topography faster than the return time of large earthquakes in this area. These findings have broad implications for the timing and magnitude of the erosional sediment flux from the Taiwan mountain belt and the mechanisms driving its orogenesis.

Item Type: Publication - Article
Programmes: CEH Programmes pre-2009 publications > Water > WA01 Water extremes
CEH Sections: Harding (to July 2011)
ISSN: 0096-3941
NORA Subject Terms: Earth Sciences
Date made live: 05 Aug 2010 10:53
URI: http://nora.nerc.ac.uk/id/eprint/9111

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