Three-dimensional velocity structure in the source region of the Noto Hanto Earthquake in 2007 imaged by a dense seismic observation

Landslide-generated waves have been major threats to coastal areas and have led to destruction and casualties. Their importance is undisputed, most recently demonstrated by the 2018 Anak Krakatau tsunami, causing several hundred fatalities. The accurate prediction of the maximum initial amplitude of landslide waves (&#951;max) around the source region is a vital hazard indicator for coastal impact assessment. Laboratory experiments, analytical solutions and numerical modelling are three major methods to investigate the (&#951;max). However, the numerical modelling approach provides a more flexible and cost- and time-efficient tool. This research presents a numerical simulation of tsunamis due to rigid landslides with consideration of submerged conditions. In particular, this simulation focuses on studying the effect of landslide parameters on &#951;max. Results of simulations are compared with our conducted physical experiments at the Brunel University London (UK) to validate the numerical model.We employ the fully three-dimensional computational fluid dynamics package, FLOW-3D Hydro for modelling the landslide-generated waves. This software benefit from the Volume of Fluid Method (VOF) as the numerical technique for tracking and locating the free surface. The geometry of the simulation is set up according to the wave tank of physical experiments (i.e. 0.26 m wide, 0.50 m deep and 4.0 m). In order to calibrate the simulation model based on the laboratory measurements, the friction coefficient between solid block and incline is changed to 0.41; likewise, the terminal velocity of the landslide is set to 0.87 m/s. Good agreement between the numerical solutions and the experimental results is found. Sensitivity analyses of landslide parameters (e.g. slide volume, water depth, etc.) on &#951;max are performed. Dimensionless parameters are employed to study the sensitivity of the initial landslide waves to various landslide parameters.

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Centroid moment tensor inversions of offshore earthquakes using a three-dimensional velocity structure model: Slip distributions on the plate boundary along the Nankai Trough

10.31223/osf.io/nbd79 ◽

2019 ◽

Author(s):

Shunsuke Takemura ◽

Ryo Okuwaki ◽

Tatsuya Kubota ◽

Katsuhiko Shiomi ◽

Takeshi Kimura ◽

...

Keyword(s):

Velocity Structure ◽

Nankai Trough ◽

Moment Tensor ◽

Three Dimensional ◽

Plate Boundary ◽

Structure Model ◽

Centroid Moment Tensor

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P-wave crustal tomography of Greece with use of an accurate two-point ray tracer

Annals of Geophysics ◽

10.4401/ag-3932 ◽

1997 ◽

Vol 40 (1) ◽

Author(s):

G. Drakatos ◽

G. Karantonis ◽

G. N. Stavrakakis

Keyword(s):

Large Scale ◽

Velocity Structure ◽

Three Dimensional ◽

Seismic Energy ◽

Aegean Sea ◽

P Wave ◽

Low Velocity ◽

Aegean Area ◽

Arrival Times ◽

Horizontal Variations

The three-dimensional velocity structure of the crust in the Aegean sea and the surrounding regions (34.0º-42.OºN, 19.0ºE-29.0ºE) is investigated by inversion of about 10000 residuals of arrival times of P-wave from local events. The resulting velocity structure shows strong horizontal variations due to the complicated crustal structure and the variations of crustal thickness. The northern part of the region generally shows high velocities. In the inner part of the volcanic arc (Southern Aegean area), relatively low velocities are observed, suggesting a large-scale absorption of seismic energy as confirmed by the low seismicity of the region. A low velocity zone was observed along the subduction zone of the region, up to a depth of 4 km. The existence of such a zone could be due to granitic or other intrusions in the crust during the uplift of the region during Alpidic orogenesis.

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TSUNAMI GENERATION AND PROPAGATION

Coastal Engineering Proceedings ◽

10.9753/icce.v13.146 ◽

1972 ◽

Vol 1 (13) ◽

pp. 146

Author(s):

Joseph L. Hammack ◽

Frederic Raichlen

Keyword(s):

Linear Theory ◽

Source Region ◽

Three Dimensional ◽

Frequency Dispersion ◽

Nonlinear Effects ◽

Its Region ◽

Experimental Results ◽

Specific Class ◽

Two Dimensional ◽

Three Dimensional Models

A linear theory is presented for waves generated by an arbitrary bed deformation {in space and time) for a two-dimensional and a three -dimensional fluid domain of uniform depth. The resulting wave profile near the source is computed for both the two and three-dimensional models for a specific class of bed deformations; experimental results are presented for the two-dimensional model. The growth of nonlinear effects during wave propagation in an ocean of uniform depth and the corresponding limitations of the linear theory are investigated. A strategy is presented for determining wave behavior at large distances from the source where linear and nonlinear effects are of equal magnitude. The strategy is based on a matching technique which employs the linear theory in its region of applicability and an equation similar to that of Korteweg and deVries (KdV) in the region where nonlinearities are equal in magnitude to frequency dispersion. Comparison of the theoretical computations with the experimental results indicates that an equation of the KdV type is the proper model of wave behavior at large distances from the source region.

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