23-25 September 2013
GEOMAR East shore
Europe/Berlin timezone
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Size-frequency relationship of submarine landslides at convergent plate margins: implications for hazard and risk assessment

Presented by Prof. Jan BEHRMANN on 24 Sep 2013 from 14:45 to 15:00
Type: Oral presentation, full-paper
Track: Oral presentations

Content

We use complete inventories of submarine landslides from the Middle America (MA) and the Central Chile (CC) trench and forearc systems to analyze the size-frequency relationship of such structures on active continental slopes. The MA forearc is characterized by subduction erosion, and the CC forearc has had an accretionary tectonic history since the Late Neogene. Both are end-member types of convergent margins around the world. Both margin segments have been mapped by high-resolution swath bathymetry at strike lengths of about 1300 km (MA) and 1000 km (CC). The Middle America forearc has 143 discernible slides with sizes ranging from 0.38 km2 to 1426 km2. Offshore Central Chile, the 62 mapped slides are 0.9 km2 to 1285 km2 in size. Slide localization is markedly different at both margin types. While they also vary strongly along strike of the individual margin, depending on forearc slope gradient, kinematic coupling between plates, or topographic structure of the downgoing plate, the size-freqency relationships are remarkably similar. This allows quantification of the incidence of a submarine slide of given size per margin segment. The relationships hold for slide sizes from 10-1000 km2, with the cut-off defined by slide size (smaller slides) and sample size (larger slides). As slide traces of 100 km2 to 300 km2 size are obliterated by tectonic deformation after about 200000 years, recurrence rates for slides of a given size can be estimated. This offers a chance to assess hazard and risk resulting from such events. It is suggested that it takes 20 to 200 plate boundary earthquakes to set off a medium-sized (> 10 km2) or larger slump or slide.

Place

Location: GEOMAR East shore
Address: Wischhofstr. 1-3 / D-24148 Kiel
Room: Lecture Hall Geb. 8A

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