When The Shaking Stops: Effects of Large Earthquakes
Earthquakes are a major geological hazard across the globe as well as one of the driving engines behind the creation and maintenance of mountainous topography. We have learned a lot in the past few decades about the spatial and temporal dimensions of earthquakes and the lasting effects they have on the Earth’s surface. Yet often overlooked in such events are a whole range of subtler changes to the land surface, due to landsliding, destruction of vegetation, and uplift or subsidence of the ground. These changes are hazards in their own right, and can cause major long-term disruption to relief or rebuilding efforts over large areas. Rivers may become choked by landslide debris, vegetation loss may lead to persistent large-scale soil erosion, surface and groundwater flows may be disrupted or stopped completely, and large landslides may block or even divert rivers away from their former courses. Importantly, these effects may occur irregularly in space, and can persist for years or decades after the earthquake.
This talk will examine some of the coseismic and post-seismic effects of large earthquakes, with a particular focus on the 12 May 2008 Wenchuan earthquake in southwestern China. That event, which had a moment magnitude of 7.9, triggered more than 50,000 landslides over an area of > 40,000 km2 in the Longmen Shan mountains of Sichuan Province. The range and scope of this surface change raises some important questions for our understanding of how mountain ranges are built and maintained in areas of active tectonics.
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Speaker
Dr Alex Densmore (University of Durham)
Biography
Alex Densmore has a PhD in Earth sciences from the University of California, Santa Cruz, and lectured at Trinity College Dublin and ETH Zurich before moving to Durham University in 2006. He is currently a Reader in Geography and the Director of Hazards Research for the interdisciplinary Institute of Hazard, Risk and Resilience. His research interests include geomorphic responses to active tectonics, the dynamics of sediment routing systems, and quantitative modelling of landscape development.
Sponsor
