Tsunami Generation and Propagation (eBook)

Tatsuhiko Saito received a Ph.D. at Tohoku University, Japan in 2003, where he studied scattering theories for applications to and interpretations of high-frequency seismograms. After graduation, as a postdoc researcher he continued to work on the investigation of seismic-wave propagation through heterogeneous earth at the National Institute of Advanced Industrial Science and Technology, and extended his research interests to seismic and tsunami generation using high-performance computing techniques on supercomputers at the Earthquake Research Institute, The University of Tokyo. He then moved to the National Research Institute for Earth Science and Disaster Prevention (NIED) (the present National Research Institute for Earth Science and Disaster Resilience) in 2010 and has been working there since as chief researcher. Following the 2011 Tohoku-Oki great earthquake, the NIED has started a new observational project, deploying more than 150 online seismic/tsunami sensors off the Pacific coast of eastern Japan to detect tsunami generation inside the focal area. He is currently engaged in research for the generation of earthquakes and tsunamis.

Tsunami Generation and Propagation

 

Chapter 1 Introduction

1.1  Offshore Tsunami Observations

1.2  The 2011 Tohoku-Oki Earthquake

1.3  Observation Inside Earthquake Focal Area

1.4  Focus of this Book

 

Chapter 2 Overview of Tsunami

2.1 Earthquake and Tsunami: A Possible Scenario in Nankai Trough, Japan

2.2 Tsunami Generation

2.3 Tsunami Propagation

2.4 Points of Tsunami Generation and Propagation

Appendix 2A Simulation Method of Tsunami Generation by an Earthquake

Appendix 2B Phase Velocity in Nonlinear Long-Wave Equations: the First Order Approximation Method

 

Chapter 3 Propagation of Tsunami and Seismic Wave

3.1 Governing Equations

  3.1.1 Stress and Strain

  3.1.2 Equation of Motion and Constitutive laws

3.2 Tsunami: Dynamics of Incompressible Fluid

  3.2.1 Fundamental Equations of Tsunami

  3.2.2 Tsunami

  3.2.3 Energy Density and Energy Flux Density for Incompressible Fluid

3.3 Seismic Wave: Elastic Dynamics

  3.3.1 P, S, and Rayleigh Waves

  3.3.2 Ocean Acoustic Wave

  3.3.3 Energy Density and Energy Flux Density for Elastic Medium

3.4 Waves in Continuum Medium

 

Chapter 4 Earthquake

4.1 A Point Source and Seismic Wave Excitation

  4.1.1 A Point Shear Dislocation Source: Equivalent Body Force and Moment Tensor

  4.1.2 Displacement Field form a Point Source

4.2 Finite Fault Model and Scaling Law

  4.2.1 Stress Drop

  4.2.2 Scaling Law

4.3 Seismic Wave Simulation

  4.3.1 Finite Difference Method

  4.3.2 Seismic Waves, Ocean Acoustic Waves, and Permanent Displacement

  4.3.3 Bridging Seismic Wave Simulation to Tsunami Propagation Simulation

Appendix 4A Seismic Wave Propagation in 2-D Space: P-SV Problem

 

Chapter 5 Tsunami Generation

5.1 Ocean Acoustic Wave and Tsunami: Different Driving Forces

5.2 Linear Potential Theory

  5.2.1 Governing Equations

  5.2.2 Solving Laplace Equation with Boundary Conditions

5.3 Generation

  5.3.1 Visualization

  5.3.2 Analytical Solutions

  5.3.3 Pressure Change

5.4 Bridging Generation to Propagation

  5.4.1 Contribution of Sea-Depth Variation

  5.4.2 Synthesis of Ocean-Bottom Pressure Record

Appendix 5A Equation (5.28)

Appendix 5B Tsunami Propagation from an Initial Height Distribution and Zero Velocity Distribution

 

Chapter 6 Propagation Simulation

6.1 Nonlinear and Dispersive Tsunami

  6.1.1 Nonlinear Wave

  6.1.2 Dispersive Waves

6.2 Tsunami Equations Derived from Equation of Motion

  6.2.1 Integration with Respect to Sea Depth: 3-D to 2-D equations

  6.2.2 Long-Wave Approximations

6.3 Numerical Simulations: Finite Difference Method

  6.3.1 Linear Long-Wave Equations: Simplest Equations

  6.3.2 Nonlinear Long-Wave Equations: Inundation

  6.3.3 Linear Dispersive Equations: Deep Ocean

  6.3.4 Nonlinear Dispersive Equations

 

Chapter 7 Epilogue

7.1 Tsunami Propagation

7.2 Tsunami Generation

7.3 Earth Science and Disaster Prevention