Delta failure events measured on Fraser Delta using scientific cabled observatory
Presented by Dr. Gwyn LINTERN on 25 Sep 2013 from 11:30 to 11:45
Type: Oral presentation, full-paper
Track: Oral presentations
The slope of the Fraser delta is prone to failure. At least six independent mechanisms have been hypothesized. Modeling by Fisheries and Oceans Canada shows that a large magnitude slide would generate a tsunami large enough to impact lives in communities of Metro Vancouver and damage hundreds of millions of dollars worth of infrastructure. Although slides of this magnitude are mostly hypothetical, there is some evidence that a large one has occurred in the past. There is also ample information about small and medium sized slides which occur on timescales of months to years. These smaller slides are capable of causing millions of dollars of damage to cables, ports and navigational structures. The Geological Survey of Canada is making use of the Ocean Networks Canada VENUS scientific cable to measure the slides, and more importantly, to measure all of the factors which are hypothesized to cause instability. With the first phase of the planned instrumentation in the water, the Delta Dynamics Laboratory, we have already measured at least two events of sufficient magnitude to cause damage to cables and other small infrastructure. The most recent event sent the large DDL platform tumbling down the delta slope. The second phase of the project comprises the Seismic Liquefaction In Situ Piezometers (SLIPs) which will be deployed, alongside the restored DDL, starting in 2013. This paper describes the failure events we have seen to date, and discusses the forcing factors which led to them. All are being measured and transmitted in real time using VENUS.