A Method to Determine the Level 1 and Level 2 Tsunami Inundation Areas for Reconstruction in Eastern Japan and Possible Application in Pre-disaster Areas - Post-Tsunami Hazard: Reconstruction and Restoration - page 139

the affected ratio but also to statistically analyze the tsunami height that affected a
particular place in a given simulated scenario. By doing so, we could estimate how
many times a location was potentially affected by a pool of tsunami scenarios with
a range of earthquake magnitudes and a range of fl ow depths.
There are two major outputs of the GIS process, which are as follows. (1) The
tsunami affected ratio: this map indicates how many times (accumulation) each
pixel inside the tsunami area is affected by a tsunami relative to the total number of
simulated scenarios. (2) The maximum tsunami inundation depth: this map illus-
trates the maximum tsunami height of the total simulated scenarios. The maximum
tsunami inundation depth at a particular point might be different than the result
obtained in the other places inside the same tsunami inundation area because the
energy radiation of the modeled tsunami is highly dependent on various aspects in
the earthquake parameters, such as strike and slip distribution, which will be dis-
cussed further in the next sub-chapter.
The maps were developed by fi rst entering all of the simulation results into a
geo-database. This database consists of all the simulated tsunami parameters, such
as the maximum tsunami heights, maximum tsunami fl ow depths and arrival times
of each scenario at the coast. Next, the map showing the affected ratio was devel-
oped by using the combine resample and raster calculator tools in ArcGIS software.
The tools were compiled in an iterative scheme in a model builder frame to auto-
matically obtain the affected ratio in each study area.
Similarly, the maps of the maximum tsunami fl ow depth were developed by
using raster calculator in an iterative scheme in the model builder frame. The itera-
tive process checked the value of the tsunami fl ow depth at a particular location
against a given raster fi le to determine whether the value was higher than the values
at the same location from the other fi les. By iterating this selection process for all
the fi les, the software could fi nd the maximum tsunami fl ow depth at all locations
inside the tsunami inundation area from all simulated scenarios.
In the fi gure above, d denotes the inundation depth in meters; suffi x i (1, 2, 3…n)
represents the number of the modeled scenario. H denotes the maximum tsunami
height at the coast. T represents the tsunami arrival time in seconds. Zone A is the
Tohoku region and Zone B is the Tonankai region.

10.3 Discussion

10.3.1 Tsunami Sources

We analyzed the maximum simulated tsunami height and maximum tsunami fl ow
depth produced by different fault models from both areas. The results were com-
pared to each other by plotting the maximum simulated tsunami height and fl ow
depth relative to the earthquake parameters, i.e., magnitude, the maximum co-seis-
mic slip, and the fault width. These three parameters were chosen because they
signifi cantly infl uence the resulting simulated tsunami parameters. For instance, the