Near-Field Tsunami Simulations of the Tohoku Earthquake, March 11,

2011

David L. GeorgeU.S. Geological Survey

Dave  Yuen   University of Minnesota

Erik O.D. SevreUniversity of Minnesota

Other co-workers

Ellen Zhu Stephen Song

Outline

• Introduction : Hazardous Free Surface Flows

• Depth-averaged Flows , Hyperbolic equations 

• GEOCLAW software, Adaptive Mesh Refinement

• Tsunami Modeling

• Tohoku Earthquake and Tsunami

• Concluding Remarks

Other slip models should considered as well

The server is Intel Xeon W5590,  in which Intel Hyper-Threading Technology is used. In this server, one physical core can simulate two logical threads.

Recently we have made Geoclaw parallel on 16 cores, using OPEN-MPI. This development has enabled us to go close to real-time simulation for near-field regimes, which take a much longer wall-clock time , than in the far field regime.

(a) One minute  (b) 15 minute

Grid employed was 1800 x 1800 grid points near the Japanese coast.

10 minutes

30 minutes

50 minutes

NEAR FIELD TSUNAMI SIMULATIONS , using high resolution 3200 x3200 grid points

VISUALIZATION OF ADAPTIVE GRID REFINEMENT ( AMR )

VISUALIZATION OF ADAPTIVE GRID REFINEMENT (AMR)

Higher resolution near the seaside (500m), and when the tsunami comes near the seaside, uses the highest resolution (about 15m) near the beach of Sendai Airport and Fukushima Nuclear Power Plant.

 First Tsunami waves coming to Fukushima power

Multiresolution visualization of AMR grid used in run-up process close to Fukushima nuclear power-plant , during the first wave attack

FOR MODELLING TSUNAMI RUN_UP PROCESSES

• It is essential to have very high resolution bathymetric maps at the coast, we have acquired from private Japanese companies  maps with 50 to 80 meter resolution at around the Tohoku coastline, out to 50 km from shore.

• The same goes for inland area, details city maps with buildings are needed for calculating the tsunami penetration distances using Riemann solvers.

CONCLUDING POINTS• GEOCLAW represents a  not-easy-to use software designed to look at

environmental fluid dynamics with hyperbolic character, based on long-wavelength and depth-averaged Ansatz ( tsunami, flood, landslides etc. ).

Uses Riemann solvers for different conditions ( dry and wet states ) , uses adaptive mesh refinement ( AMR) to solve multi-scale problems, time-steps are synchronized for all scales at one reference time-stopping point.

OPEN-MP version has been developed, MPI is being tested.

• We have looked at the run-up at the nuclear Plant at Fukushima this requires very high resolution of bathymetric data for sea and also accurate inland map with buildings ( GIS  data ).

Problem is multi-disciplinary and requires a team of applied mathematics, fluid dynamics, visualization, geo-engineering.

Bottom line is that higher  run-up waves are produced with finer scale bathymetric data agree with analytical results by George Carrier and Harry Yeh ( 2003) can increase from 10 to 15 meters with finer scale map.

• We need better and finer scale bathymetric data near the coast for accurate assessment of tsunami wave heights.