Complex seafloor bathymetry can create significant challenges for subsurface imaging and geologic interpretation of seismic exploration and monitoring data. Steep seafloor canyons that cut through continental shelf areas can produce very strong seismic wavefield distortions. Neglecting such wavefield complexity can result in inaccurate velocity models, significant imaging errors, misleading amplitudes, and erroneous geologic interpretations. We have evaluated the kinematic and dynamic effects of seismic prism waves generated by seafloor canyons. Prism waves are seismic waves that undergo consecutive reflections at a scattering interface before propagating to the recording sensor array. We have demonstrated that strong prism waves can be generated for realistic seafloor canyon geometries, and we determined how their adverse effects can contaminate seismic imaging and velocity estimation.

Abstract：Road side barriers are constructed to protect passengers and contain vehicles when a vehicle crashes into a barrier. In general, full-scale crash testing needs to be carried out if a geometrically and structurally equivalent barrier has not previously been proven to meet the requirements of containing the vehicle and dissipating sufficient impact energy for passenger protection. As full-scale crash testing is very expensive, the number of data that can be measured in a test is usually limited, and it may not always be possible to obtain good quality measurements in such a test, a reliable and efficient numerical simulation of crash testing is therefore very useful. This paper presents finite element simulations of a 3-rail steel road traffic barrier under vehicle impact. The performance levels defined in Australian Standards AS5100 Clause 10.5 for these barriers are checked. The numerical simulations show that the barrier is able to meet low performance levels. However, the maximum deceleration is higher than the acceptable limit for passenger protection. If present, a kerb launches the vehicles into the barrier, allowing for the possibility of overriding the barrier under certain circumstances, but it redirects the vehicle and reduces the incident angle, which reduces impact force on the barrier. Further investigation into all common kerb profiles on roads should be carried out, as only one kerb profile is investigated in this study.The performance of the roadside barrier under vehicle impact assists in minimising the occurrence and/or severity of injury to the vehicle passengers and other motorists. Guardrails such as the two-rail steel barrier and the three-rail steel barrier are a critical road safety feature and are commonly used in Western Australia. As the new standard (AS5100 2004) [1] gives different low and regular performance levels for guardrails, and sets out the new criteria for design and performance of guardrail barriers, it is imperative to check if these existing steel barriers meet the performance requirement. AS5100 defines and specifies that low performance levels are for the effective containment of light vehicles with low traffic volumes, and regular performance levels are for the effective containment of cars, heavy utilities and light to medium mass trucks on freeways, highways and main roads. Tab.1 describes the low and regular performance levels. Several other performance levels are defined in AS5100. However, only the regular and low performance levels are tested in this study. Tab.1 Required performance levelLevel Vehicles Design speed/ (km·h −1 ) Impact angle /(°) 0.8 t small car 70 20 Low 2.0 t utility 70 25 0.8 t small car 100 20 2.0 t utility 100 25 Regular 8.0 t truck 80 15Usually vehicle impact tests are conducted to verify the performance of guardrails. However, it is not economically feasible to perform full-scale field-testing in a wide range of parameters. Moreover, such crash tests, despite their considerable costs, furnish relatively little information. Numerical ...

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