Submarine Landslide Tsunami Linearity

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This page documents tests on the scaling of tsunami waves with Earthquake volume

As part of our work developing a Probabilistic Tsunami Hazard Assessment (PTHA) for submarine landslide generated tsunamis we are investigating the scaling of tsunami waves with volume of the landslide.

For the initial test we are using the TOPICS submarine-landslide-generated-tsunami initialisation code. There are some questions as to its applicability in the shallow canyon environment but it will do for the initial investigation.

In TOPICS both the volume is specified and the length/width and maximum thickness. This overspecifies the problem (although as it is maximum thickness there is some room for a range of volumes to be consistent with the given dimensions).

We are using the standard Nicholson Canyon setup used in XXXXXXXX with four different volumes: 100,000,000 m^3, 400,000,000 m^3, 333,333,333 m^3 and 1,000,000,000 m^3. The maximum thickness is held constant at 200 m. The landslide length and width are taken as equal and are 2,400 m, 1,500 m, 1,400 m and 760 m respectively for the four cases.

In order to investigate the influence of different dimensions given the same volume we are doing three simulations with volume set as 400,000,000 m^3 and maximum thickness given as 50 m, 100 m and 200 m.

There does not seem to be a strong relationship between volume and water height (i.e. changing the thickness has a large effect on wave height at the places of interest. Some areas appear to be inundated while others aren't. Is this correct or is this a bug of the inundation programme?

Outputting data at certain points

William Power provided the file Cook_points.csv to output time series or maximum wave heights at. This Includes all of Marlborough sounds which might be more than is needed so we may wish to cut it down.

As a start to cutting it down we will just use a box 174 - 175.5 in longitude, -41.8 - -41.15 in latitude. This will include some of the inner Marlborough sounds but not to much.

First I needed to dos2unix the file to get rid of dos endoflines Then I used the following awk file convert_Cook.awk

if ((x > 174) && (x < 175.5) && (y > -41.8) && (y < -41.15)) {
print $1, $2, " 0"

awk -f convertCook < Cook_points.csv > Cook_points.out

The .awk file timeseries.awk given below post-processes the output data to give time and the sea level heights. X and Y are also given in case these are mixed up in parallel runs.

FS=" |:"
if ($1 == "#") {
# get column indices of relevant fields
for (i=1; i <= NF; i++) {
if ($i == "H")
iH = $(i-1);
if ($i == "x")
ix = $(i-1);
if ($i == "y")
iy = $(i-1);
if (NR > 1) {
print $1, $ix, $iy, $iH

Which is run using the command

GfsOutputLocation {step = 1} { awk -f timeseries.awk > timeseries_interp1.out } Cook_points.out { interpolate = 1}

Currently I am exploring whether or not it is best to interpolate (1 or 0). I am also trying to set it so that if the land is not inundated then the height is set to zero - I am not sure whether this is best or whether it is better to output wave height and also Z for that point and compare this. I tried only outputting if P>0 but that made minimal difference.

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