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 Jun 1, 2006, 6:46:53 PM (18 years ago)
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documentation/experimentation/MOST_ANUGA.tex
r3044 r3045 22 22 \marginparwidth 0.5pt 23 23 \textwidth \paperwidth 24 %\advance\textwidth 2.5in24 \advance\textwidth 2.5in 25 25 %\setstretch{1.5} 26 26 %\parindent 0pt 27 27 %\parskip 2pt 28 28 29 \title{Inundation Modelling of an Earthquake Source: Where is the boundary?}29 \title{Inundation Modelling from an Earthquake Source} 30 30 \date{} 31 31 … … 38 38 The ATWS aims to detect and warn the community 39 39 of tsunamigenic events as well as develop community education programs for 40 preparation of the event. Risk mitigation involves understanding the relative risk 41 of tsunamis to communities so that appropropriate evacuation plans can be put in place. 40 preparation of the event. Risk mitigation involves understanding the relative 41 risk 42 of tsunamis to communities so that appropropriate evacuation plans can be 43 put in place. 42 44 To develop an understanding of the risk, the Risk Research Group is developing 43 decision support tools to assist emergency managers. These tools consist of inundation 44 maps, damage modelling overlaid on aerial photography of the region which details critical 45 decision support tools to assist emergency managers. These tools consist 46 of inundation 47 maps and damage modelling overlaid on aerial photography of the region 48 detailing critical 45 49 infrastructure. This report deals with the tsunami inundation modelling 46 and the interaction with the event propagation model, Method of Splitting Tsunami (MOST). 50 and the interaction with the event propagation model, Method of 51 Splitting Tsunami (MOST). 47 52 48 53 \end{abstract} … … 53 58 \label{intro} 54 59 55 Following the risk methodology of determining the hazard, consequence, 56 exposure to find the overall risk, the first step in determining 57 tsunami risk is understanding the hazard. Tsunamiscan be generated by60 To determine tsunami risk, we follow the risk methodology of 61 determining the hazard, consequence and 62 exposure. The tsunami hazard can be generated by 58 63 submarine earthquakes and mass failures, as well as volcanoes and asteroid 59 64 impacts. Here, we concentrate on submarine earthquakes only. The 60 65 Method of Splitting Tsunami (MOST) models the earthquake event and 61 66 propagates the tsunami wave in deep water, \cite{titov:most}. 62 Due to the wavelength and water depth, a linear model is appropriate. GA 63 has developeda preliminary hazard map for Australia which is based67 GA has used this model to develop 68 a preliminary hazard map for Australia which is based 64 69 on generating a series of earthquakes along the relevant subduction 65 70 zones surrounding Australia. The map details the average wave height 66 71 at the 50m contour line and has been used in nominating areas of 67 72 detailed inundation modelling by the Fire and Emergency Services Authority 68 in Western Australia. 69 70 The next step in developing the tsunami risk is to determine the 71 consequence of the tsunami wave once is reaches the coastline. 72 Here, we use the software tool ANUGA which solves the shallow water wave equation to 73 calculate as the maximum inundation depth ashore. ANUGA uses the 74 finite volume technique, \cite{ON:modsim} whose 75 advantage is that the cell resolution can be changed 73 in Western Australia. MOST uses a finite difference technique and is 74 based on a fixed grid structure. Inputs include bathymetric data, typically 75 on the order of 100m grid spacing, and details regarding the source, such 76 as location, size, slip angle, for example. 77 78 In determining the 79 consequence of the tsunami wave once is reaches the coastline, 80 we use the software tool ANUGA which solves the shallow water 81 wave equation to 82 calculate the maximum inundation depth ashore. ANUGA uses the 83 finite volume technique, \cite{ON:modsim} with the 84 advantage being that the cell resolution can be changed 76 85 according to areas of interest and that wetting and drying 77 86 is treated robustly as part of the numerical scheme. 78 ANUGA is continually being developed and validated. ANUGArequires a number87 ANUGA requires a number 79 88 of inputs including on and offshore data, 80 89 an initial condition (such as the tidal height), forcing … … 82 91 the tsunami wave). This report discusses the details of the latter point, 83 92 i.e the interaction between ANUGA and MOST 84 focussing on the location at which information is "best" passed from one model 85 to the next. Drivers for this study surround computational processing time 93 focussing on the location at which information is ``best'' 94 passed from one model 95 to the next. 96 97 Drivers for this study surround computational processing time 86 98 to develop both {\it tactical} and {\it strategic} decision support tools. 87 Tactical tools support real time consequence prediction for emergency manager use 99 Tactical tools support ``real time'' consequence prediction for 100 emergency manager use 88 101 to obtain assessments of tsunami impact and expected 89 102 consequences to guide initial resource deployment. Strategic tools are based 90 on using estimated recurrence rates of tsunamigenic events , the modelled inundation91 and associated damage\footnote{This activity is also part of the Risk Research Group 92 which uses the National Building Exposure Database, see 93 http://www.ga.gov.au/urban/projects/ramp/NBED.jsp} (the exposure) 94 to present a national tsunami risk map.On another strategic level,103 on using estimated recurrence rates of tsunamigenic events (the hazard), 104 the modelled 105 inundation and associated damage (exposure) 106 to present a national tsunami risk map. 107 On another strategic level, 95 108 the precomputed simulations 96 109 and risk maps will comprise a library of scenarios for the Australian Tsunami 97 Warning System to assist in mitigation, warning, response and community recovery98 in the event of a tsunami disaster.110 Warning System to assist in mitigation, warning, response and community 111 recovery in the event of a tsunami disaster. 99 112 100 113 \section{The modelling environment} … … 108 121 calls for interpolation from the MOST output to the defined boundary. As 109 122 MOST is modelling the tsunami wave from its source and is often made 110 up of a series of waves, We need to account for its time varying nature. 123 up of a series of waves, 124 ANUGA needs to account for its time varying nature. 111 125 ANUGA deals with a time varying boundary in the following way. 112 126 … … 115 129 \label{compare} 116 130 117 This section details a range of comparisons at "gauge" points located 118 within the study area, including the boundary. The purpose is to ascertain 119 any relationships between the bathymetric topography and the "matching" 131 This section details a range of comparisons at ``gauge'' points located 132 within the study area, including the boundary. Note, these gauges are 133 constructed for computational purposes only and are not physical tide 134 gauges. The purpose is to ascertain 135 any relationships between the bathymetric topography and the ``matching'' 120 136 of the ANUGA and MOST outputs. The difficult question is to 121 how to define this "matching". Here, we define the measure of blah de blah.137 how to define this matching. Here, we define the measure of blah de blah. 122 138 123 139 Firstly, at what water depth should we place the ANUGA boundary? And where … … 127 143 when the depth of the water, 128 144 $d$, becomes less than one half of the wavelength of the wave, 129 $\lambda$\footnote{http://electron4.phys.utk.edu/141/dec8/December%208.htm}. 130 Wavelengths can often be of the order of 100km which would place the transition 131 at 50km! This then aligns with the following NOAA statement, 145 $\lambda$ 146 \footnote{http://electron4.phys.utk.edu/141/dec8/December\%208.htm}. 147 Wavelengths can often be of the order of 100km which would place the 148 transition at 50km! This then aligns with the following NOAA statement, 132 149 "[t]sunami waves are shallowwater waves with long periods and wave lengths." 133 \footnote{http://www.pmel.noaa.gov/tsunamihazard/tsunami _faqs.htm}150 \footnote{http://www.pmel.noaa.gov/tsunamihazard/tsunami\_faqs.htm} 134 151 135 152 Unfortunately, this doesn't help the modelling effort as the study area 136 is constrained by UTM zones and the computational load. However, the former issue 137 is planned for investigation and the latter is underway through the parallelisation 138 of ANUGA. 153 is constrained by UTM zones and the computational load. However, the 154 former issue 155 is planned for investigation and the latter is underway through the 156 parallelisation of ANUGA. 139 157 140 158 need some words here about why 100m has been chosen … … 145 163 \subsection{Onslow case study} 146 164 147 Picture of grid layout, ANUGA boundary and choice of gauge locatations. 148 149 Table of gauge locations 150 151 \begin{table}{llll} 152 \label{gaugetable} 165 \begin{figure} 166 \caption{Diagram of MOST grid layout, ANUGA boundary and gauge 167 locatations.} 168 \label{fig:setup} 169 \end{figure} 170 171 \begin{table} 172 \label{table:gauge} 153 173 \caption{Gauge locations used for comparative study} 174 \centering 175 \begin{tabular}{llll}\hline 154 176 Gauge number & Latitude & Longitude & Elevation (m) \\ \hline 155 177 & & & 372 \\ \hline 178 \end{tabular} 156 179 \end{table} 157 180 158 comparison table 159 160 \begin{table}{llll} 161 \label{comparisontable} 162 \caption{Comparison in output when ANUGA boundary at 50m contour and 100m contour.} 181 182 \begin{table} 183 \label{table:comparison} 184 \caption{Comparison in output when ANUGA boundary at 50m contour and 185 100m contour.} 186 \centering 187 \begin{tabular}{lll}\hline 163 188 Gauge number & Boundary at 50m contour & Boundary at 100m contour \\ \hline 164 & & & some sort of measure of fit \\ \hline 189 & & some sort of measure of fit \\ \hline 190 \end{tabular} 165 191 \end{table} 166 192 … … 172 198 \begin{thebibliography}{99} 173 199 174 \bibitem{ON:modsim} Nielsen, O., S. Robers, D. Gray, A. McPherson, and A. Hitchman (2005) 200 \bibitem{ON:modsim} Nielsen, O., S. Robers, D. Gray, A. McPherson, and 201 A. Hitchman (2005) 175 202 Hydrodynamic modelling of coastal inundation, MODSIM 2005 International 176 203 Congress on Modelling and Simulation. Modelling and Simulation Society … … 178 205 http://www.mssanz.org.au/modsim05/papers/nielsen.pdf 179 206 180 \bibitem{titov:most} Titov, V.V., and F.I. Gonzalez (1997), Implementation and testing of 207 \bibitem{titov:most} Titov, V.V., and F.I. Gonzalez (1997), Implementation 208 and testing of 181 209 the Method of Splitting Tsunami (MOST) model, NOAA Technical Memorandum 182 210 ERL PMEL112.
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