What Goes Under Down Under

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What Goes Under Down Under? Computational
Modelling of Tsunami Impacts Ole Nielsen,
Jane Sexton, Duncan Gray, Nick Bartzis Risk
Research Group Geospatial and Earth Monitoring
Division
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Indian Ocean Tsunami26th Dec 2004

• Tsunamis are real and pose a threat to coastal
  communities
• Risk to tsunami disasters can be reduced by
• Early warning systems (detection prediction)
• Quantification of risk ( actual mitigation)
• Modelling is a necessary component in both

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West Java Earthquake
West Java earthquake and tsunami 17th July 2006
(Mw 7.8)

• Max run up distance 200m
• Max run up height 9m

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2006 Java Tsunami Impact in Australia
4 wheel drive moved 10 m inland
Campsites destroyed
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Crescent City Nov 2006

• Mw 8.1 off Japan
• Warning called off due to negligible intensity
• However, some localised damage in CC
• This shows that scientists need to pay more
  attention to local topographies and how they
  might create wave resonances. (Costas Synolakis,
  director of the Tsunami Research Center at UCLA)

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Okushiri Island 1993 Tsunami
Predicting Tsunami Run Up The Importance of
Modelling

• magnitude 7.8 earthquake
• 32 m run up height

Click here to see why
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ANUGA Inundation Modelling Tool

• Collaborative work between ANU and GA since 2004
• Conserved form of the Shallow Water Wave
  Equations Nonlinear and suitable for depth -gt 0
• Finite-volume discretisation on triangular
  meshes Allow complex geometries and
  obstacles
• A range of visualisation options
• Extensible to any conservation law on 2d meshes

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ANUGA Software Development

• Written in Python
• Object Oriented
• Bottlenecks written in C
• Overall framework is general
• Open source components
• Automated unit testing
• Subversion for revision control
• Issue tracking (TRAC)
• Few dependencies (we travel light)

Loop through edges that lie on the boundary and
associate them with callable boundary objects
depending on their tags for k, (vol_id, edge_id)
in enumerate(x) tag self.boundary
(vol_id, edge_id) if boundary_map.has_ke
y(tag) B boundary_maptag
Callable Boundary Object if B
is not None
self.boundary_objects.append(((vol_id, edge_id),
B)) self.neighboursvol_id
, edge_id -len(self.boundary_objects)

int _rotate(double q, double n1, double n2)
/Rotate the momentum component q (q1, q2)
from x,y coordinates to coordinates based on
normal vector (n1, n2). To rotate in
opposite direction, call rotate with (q, n1, -n2)
/ double q1, q2 q1 q1 //uh
momentum q2 q2 //vh momentum
//Rotate q1 n1q1 n2q2 q2
-n2q1 n1q2 return 0
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Detailed Validation Comparison
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ch7
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Parallelisation of ANUGA

• Brings run time for typical scenario down from
  almost a week to less than a day
• Developed and implemented by Stephen Roberts and
  Linda Stals at the Mathematical Sciences
  Institute, ANU
• Uses Python binding to the MPI library (pypar)
  developed at ANU

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Initial Mesh (Okushiri example)
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Partitioned Mesh 4 CPUs
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Timings (Okushiri simulation)
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Impact Modelling Flow (Decomposed)
ANUGA
MOST or URS
Elevation Data
Tsunami Event
Nonlinear Inundation Model
Open Water Propagation
GIS Decision Support
National Building Exposure Database
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Tsunami Impact Modelling With FESA WA
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We Need The Grid

• ANUGA relies on onshore and offshore elevation
  data.
• ANUGA relies on triangular meshes.
• ANUGA relies on boundary conditions from a range
  of tsunami genesis and propagation models.
• ANUGA outputs time histories of water levels and
  momenta for use with other applications.

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Data Horror Story
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Wish List for Xmas

• Machine readable access to elevation data
• Send clipping polygon
• Receive collection of points within polygon along
  with metadata, quality measures and lineage
• Machine readable access to mesh services
• Machine readable access to output from other
  models.
• HPC galore
• Replace or embed current NetCDF files using some
  ML format. Can you help (e.g. Andrew Woolf)?

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Challenges and Future Plans

• Validation of Dec 2004 Jul 2006 events
• Emerging Collaborations ATWS, EMA, NSW, ANU, UQ
  (ACCESS), GNS, NIWA, Sri Lanka, Thailand,
  need for standards
• Public Open Source release of ANUGA (including
  data used for the Okushiri Island Validation!)

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Hobby Horses

• Data need to be machine readable
• Data need to be machine readable
• Data need to be masjine redabel
• Datta ned to be masjin redbl
• Open Source OF COURSE!
• Portability
• Leveraging
• Documentation of process (e.g. lineage of derived
  data)
• If it isnt online it doesnt exist
• If it isnt tested - it doesnt exist
• Automation is everything in this game

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Thank you!
Further information Email Ole.Nielsen_at_ga.gov.au
Websites (Google search) Inundation Modelling
Geoscience Australia