The effect of multiple splay fault rupture on tsunamis

2020 ◽  
Author(s):  
Iris van Zelst ◽  
Leonhard Rannabauer ◽  
Alice-Agnes Gabriel ◽  
Ylona van Dinther
Keyword(s):  
Vertical Surface ◽  
Tsunami Hazard ◽  
Fault Rupture ◽  
Geophysical Research ◽  
Large Wave ◽  
Surface Displacements ◽  
Seismic Cycles ◽  
Splay Faults ◽  
Splay Fault ◽  
The Waves

<p>Earthquake rupture on splay faults in subduction zones could pose a significant tsunami hazard, as they could accommodate more vertical displacement and are situated closer to the coast. To better understand this tsunami hazard, we model splay fault rupture dynamics and tsunami propagation and inundation constrained by a geodynamic seismic cycle (SC) model; building on work presented in Van Zelst et al. (2019). This two-dimensional modelling framework considers geodynamics, seismic cycles, dynamic ruptures, and tsunamis together for the first time. The SC model provides six blind splay fault geometries, self-consistent stress and strength conditions, and heterogeneous material properties in the domain. We find that all six splay faults are activated when the megathrust ruptures. The largest splay fault closest to the nucleation region ruptures immediately when the main rupture front passes the branching point. The other splay faults are activated through dynamic stress transfer from the main megathrust rupture or reflected waves from the surface. Splay fault rupture results in distinct peaks in the vertical surface displacements with a smaller wavelength and larger amplitudes. The effect of the vertical surface displacements also translates into the resulting tsunami, which consists of one large wave for the megathrust-only model and seven waves for the model including splay faults. Here, six of the waves can be attributed to the splay faults and the seventh wave results from the shallow tip of the megathrust. The waves from the rupture including splay faults have larger amplitudes and result in two episodes of coastal flooding. The first episode is due to the large wave caused by rupture on the largest splay fault nearest to the coast. The second flooding episode results from the combination and interference of the waves caused by the rest of the splay faults and the shallow megathrust tip. In contrast, the tsunami caused by rupture on only the megathrust has only one episode of flooding. Our results suggest that larger-than-expected tsunamis could be attributed to rupture on large splay faults. When multiple smaller splay faults rupture their effect on the tsunami might be hard to distinguish from a pure megathrust rupture. Considering the significant effects splay fault rupture can have on a tsunami, it is important to understand splay fault activation and to consider them in hazard assessment.</p><p>References:</p><p>Van Zelst, I., Wollherr, S., Madden, E. H. , Gabriel, A.-A., and Van Dinther, Y. (2019). Modeling megathrust earthquakes across scales: one-way coupling from geodynamics and seismic cycles to dynamic rupture. Journal of Geophysical Research: Solid Earth, 124, https://doi.org/10.1029/2019JB017539</p><p></p>

Relaxation of the south flank after the 7.2-magnitude Kalapana earthquake, Kilauea Volcano, Hawaii

1994 ◽  
Vol 84 (1) ◽  
pp. 133-141
Author(s):  
John J. Dvorak ◽  
Fred W. Klein ◽  
Donald A. Swanson
Keyword(s):  
Rift Zone ◽  
Vertical Surface ◽  
Kilauea Volcano ◽  
Adjacent Segment ◽  
The South ◽  
Surface Displacements ◽  
Kīlauea Volcano ◽  
Parkfield Earthquake ◽  
Largest Aftershock ◽  
Large Earthquakes

Abstract An M = 7.2 earthquake on 29 November 1975 caused the south flank of Kilauea Volcano, Hawaii, to move seaward several meters: a catastrophic release of compression of the south flank caused by earlier injections of magma into the adjacent segment of a rift zone. The focal mechanisms of the mainshock, the largest foreshock, and the largest aftershock suggest seaward movement of the upper block. The rate of aftershocks decreased in a familiar hyperbolic decay, reaching the pre-1975 rate of seismicity by the mid-1980s. Repeated rift-zone intrusions and eruptions after 1975, which occurred within 25 km of the summit area, compressed the adjacent portion of the south flank, apparently masking continued seaward displacement of the south flank. This is evident along a trilateration line that continued to extend, suggesting seaward displacement, immediately after the M = 7.2 earthquake, but then was compressed during a series of intrusions and eruptions that began in September 1977. Farther to the east, trilateration measurements show that the portion of the south flank above the aftershock zone, but beyond the area of compression caused by the rift-zone intrusions and eruptions, continued to move seaward at a decreasing rate until the mid-1980s, mimicking the decay in aftershock rate. Along the same portion of the south flank, the pattern of vertical surface displacements can be explained by continued seaward movement of the south flank and development of two eruptive fissures along the east rift zone, each of which extended from a depth of ∼3 km to the surface. The aftershock rate and continued seaward movement of the south flank are reminiscent of crustal response to other large earthquakes, such as the 1966 M = 6 Parkfield earthquake and the 1983 M = 6.5 Coalinga earthquake.

A mega-splay fault system and tsunami hazard in the southern Ryukyu subduction zone

2013 ◽  
Vol 362 ◽  
pp. 99-107 ◽  
Author(s):  
Shu-Kun Hsu ◽  
Yi-Ching Yeh ◽  
Jean-Claude Sibuet ◽  
Wen-Bin Doo ◽  
Ching-Hui Tsai
Keyword(s):  
Subduction Zone ◽  
Tsunami Hazard ◽  
Fault System ◽  
Splay Fault

The energy and action of small waves riding on large waves

1988 ◽  
Vol 189 ◽  
pp. 443-462 ◽  
Author(s):  
Frank S. Henyey ◽  
Dennis B. Creamer ◽  
Kristian B. Dysthe ◽  
Roy L. Schult ◽  
Jon A. Wright
Keyword(s):  
Coordinate System ◽  
Hamiltonian Formulation ◽  
Capillary Waves ◽  
Two Dimensional ◽  
Scale Separation ◽  
Large Wave ◽  
Action Density ◽  
Lagrangian Equations ◽  
Small Wave ◽  
The Waves

We derive the dynamics of small waves riding on larger waves using a canonical, Hamiltonian formulation. The small waves are treated linearly and their energy is derived to all orders in the scale separation between the waves. Our results are similar to those of Longuet-Higgins (1987), but we have extended his calculations to include gravity-capillary waves and to allow for a more general, two-dimensional, large-wave field. Our result for the small-wave Hamiltonian is expressed in both Eulerian (horizontal) coordinate system and a non-inertial system determined by the large wave's surface. On further assuming scale separation between the small and large waves the averaged Lagrangian equations and the action density are derived. Action conservation is explicitly demonstrated.

On nonlinear wave groups and crest statistics

2009 ◽  
Vol 620 ◽  
pp. 221-239 ◽  
Author(s):  
FRANCESCO FEDELE ◽  
M. AZIZ TAYFUN
Keyword(s):  
Nonlinear Effects ◽  
Theoretical Expression ◽  
Large Wave ◽  
Weakly Nonlinear ◽  
The North ◽  
Wave Measurements ◽  
Surface Displacements ◽  
Skewness Coefficient ◽  
Broadband Waves ◽  
Generalized Distribution

We present a second-order stochastic model of weakly nonlinear waves and develop theoretical expressions for the expected shape of large surface displacements. The model also leads to an exact theoretical expression for the statistical distribution of large wave crests in a form that generalizes the Tayfun distribution (Tayfun, J. Geophys. Res., vol. 85, 1980, p. 1548). The generalized distribution depends on a steepness parameter given by μ = λ3/3, where λ3 represents the skewness coefficient of surface displacements. It converges to the Tayfun distribution in narrowband waves, where both distributions describe the crests of all waves well. In broadband waves, the generalized distribution represents the crests of large waves just as well whereas the Tayfun distribution appears as an upper bound and tends to overestimate them. However, the theoretical nature of the generalized distribution presents practical difficulties in oceanic applications. We circumvent these by adopting an appropriate approximation for the steepness parameter. Comparisons with wind-wave measurements from the North Sea suggest that this approximation allows both distributions to assume an identical form with which we can describe the distribution of large wave crests fairly accurately. The same comparisons also show that third-order nonlinear effects do not appear to have any discernable effect on the statistics of large surface displacements or wave crests.

scholarly journals Regional tsunami hazard from splay faults in the Gulf of Oman

2021 ◽  
pp. 110169
Author(s):  
Amin Rashidi ◽  
Denys Dutykh ◽  
Nasser Keshavarz ◽  
Laurence Audin
Keyword(s):  
Tsunami Hazard ◽  
Gulf Of Oman ◽  
Splay Faults

scholarly journals WAVES GENERATED BY A PISTON-TYPE WAVEMAKER

1970 ◽  
Vol 1 (12) ◽  
pp. 36 ◽  
Author(s):  
Ole Secher Madsen
Keyword(s):  
Mathematical Model ◽  
Finite Number ◽  
Wave Height ◽  
Finite Amplitude ◽  
Governing Equations ◽  
Approximate Evaluation ◽  
Large Wave ◽  
Wave Heights ◽  
The Waves ◽  
Theoretical Results

When a wavemaker generates a finite number of waves, it has been found that one of the first and one of the last waves in such a burst is considerably larger than the average A mathematical model, based on the linearized governing equations, is used for the particular problem of the waves generated by a sinusoidally moving piston-type wavemaker starting from rest Theoretical results for the magnitude of the large wave relative to the average agree fairly well with experiments, however, the actual wave height is smaller in the experiments than predicted by theory It is shown, by extending the classical wavemaker theory to second order, that finite amplitude effects do not offer an explanation However, pistons rarely fit the tank dimensions exactly, and an approximate evaluation indicates that the discrepancy between predicted and observed wave heights can be attributed to the effects of leakage around the piston.

Relaxation Models for Wave Phenomena in Liquid-Vapor Bubble Flow in Channels

1998 ◽  
Vol 120 (2) ◽  
pp. 369-377 ◽  
Author(s):  
Z. Bilicki ◽  
D. Kardas ◽  
E. E. Michaelides
Keyword(s):  
Heat Conduction ◽  
Numerical Solutions ◽  
Relaxation Model ◽  
Vapor Bubbles ◽  
Large Wave ◽  
New Model ◽  
Energy Equations ◽  
The Waves ◽  
Wave Phenomena ◽  
Liquid Vapor

We examine wave characteristics of a liquid-vapor mixture in order to investigate certain features of the homogeneous relaxation model. The model is described by one-dimensional averaged mass, momentum, energy equations, and a rate equation. Since the homogeneous relaxation model delivers a qualitative incompatibility of numerical and experiment results of large wave propagation, it is extended so as to take into account the heat conduction in the liquid surrounding vapor bubbles. With this extension, the effects of spreading and damping of the waves in the numerical solutions are similar to those observed in the experiment. Thus, a new model is created, the homogeneous relaxation-diffusion model which contains two physical quantities—the relaxation time and macroscopic heat conduction coefficient. Both quantities are determined based on experimental data. It seems that the results obtained from the new model agree well qualitatively with the experiments.

Global structure and properties of ULF waves in the ion foreshock observed in a Hybrid-Vlasov simulation.

2021 ◽  
Author(s):  
Kun Zhang ◽  
Seth Dorfman ◽  
Urs Ganse ◽  
Lucile Turc ◽  
Chen Shi
Keyword(s):  
Space Physics ◽  
Ulf Waves ◽  
Ion Distribution ◽  
Geophysical Research ◽  
Energetic Ions ◽  
Ultralow Frequency ◽  
Ulf Wave ◽  
Wave Normal ◽  
The Waves ◽  
Wave Properties

<p>Energetic ions reflected and accelerated by the Earth’s bow shock travel back into the solar wind, forming the ion foreshock, and generate ultralow frequency (ULF) waves. Such ULF waves have been extensively studied over the past few decades using satellite measurements. However, the spatial variations of the wave properties cannot be well resolved by satellite observations due to the limited number of available spacecraft simultaneously inside the ion foreshock. Therefore, we conduct a global survey of the ULF wave properties in the ion foreshock through analysis of a Vlasiator (a hybrid-Vlasov code) simulation. Previous studies validated that this simulation well reproduced Earth’s foreshock and the ULF waves in it [e.g., Palmroth et al., 2015; Turc et al., 2018]. Here we focus on the wave properties, including frequency, ellipticity, polarization, wave normal angle and growth rate, of the well-known 30-sec wave and its multiple harmonics. We report that the ULF waves near the edge of the foreshock are very different from the waves in the center of the foreshock. We also show the related ion distribution and discuss the connection between the observed ion beams and ULF waves, aiming at understanding the cause of the observed differences in wave properties.</p><p> </p><p>This study is supported by NASA grant 80NSSC20K0801. Vlasiator is developed by the European Research Council Starting grant 200141-QuESpace, and Consolidator grant GA682068-PRESTISSIMO received by the Vlasiator PI. Vlasiator has also received funding from the Academy of Finland. See www.helsinki.fi/vlasiator</p><p> </p><p>Palmroth, M., et al. (2015), ULF foreshock under radial IMF: THEMIS observations and global kinetic simulation Vlasiator results compared, J. Geophys. Res. Space Physics, 120, 8782–8798, doi:10.1002/2015JA021526.</p><p>Turc, L., Ganse, U., Pfau-Kempf, Y., Hoilijoki, S., Battarbee, M., Juusola, L., et al. (2018). Foreshock properties at typical and enhanced interplanetary magnetic field strengths: results from hybrid-Vlasov simulations. Journal of Geophysical Research: Space Physics, 123, 5476–5493. doi:10.1029/2018JA025466.</p>

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