Recently GeoClaw has been run on all the events with the setup archived
in the github repository in the directory
LagoonCreekTsunamis
Gauge plots¶
Gauge plots similar to those shown for Sample Results for BL13M can be found at gauge_plots
Zip file of gauge output¶
This zip file contains the time series at each of the 5 gauges for all of the events, if you want to plot them together with your own results:
The files included in this zip file are in the same format as in the zip file described in the Sample Results for BL13M, and consist of a header followed by lines with three columns for the time series at the gauge:
time (seconds), depth (m), surface elevation (m)Maximum inundation depth at Gauges¶
One way to compare the events is to plot the maximum depth over the simulation
at one location, e.g. one of the onshore gauges.
This plots below for each gauge show this value for each event
after sorting from smallest to largest. The width of each bar is proportional
to the weight assigned to the event in the logic tree shown at
Cascadia CoPes Hub Ground Motions and Tsunami
Sources.
Gauge Locations
Maximum inundation depth at Gauge 1
Maximum inundation depth at Gauge 2
Maximum inundation depth at Gauge 3
A few things to note:
In general the events with 10 in the name (using the Strasser et al 2010 magnitude-area relationship from the logic tree) have the largest magnitude, so it is not surprising that most of these give greater inundation than other events.
FL10D has much greater depths than any other event. This event is Mw 9.2 with substantial uplift at the southern end, near Lagoon Creek.
BR16M and BR16D have little flooding at Gauge 1 and none at Gauges 2 and 3. These events have uplift in this region.
Plots of the slip and seafloor deformation for each of the 36 sources can be found in the Powerpoint slides included in the data distribution. The pdf version can also be viewed here.
The plots shown above were computed with the Jupyter notebook
geoclaw_multirun/CompareGaugeMaxima.ipynb
in the repository. Here is a
rendered version of the notebook.
PTHA¶
The 36 Cascadia CoPes Hub Sources were not originally designed for Probabilistic Tsunami Hazard Assessment (PTHA), and may not cover the full range of CSZ earthquakes. Moreover, this is a relatively small set of sources.
However, the relative likelihood of these particular events (as defined by the weights in the logic tree) sum to 1, and might be viewed as conditional probabilities (i.e. given that a major CSZ earthquake occurs, the weight is the relative probability of each). These weights can be combined with a presumed annual probability that such an event occurs in order to obtain an annual probability of each event. These can then be used (together with tsunami simulations of each event) to perform PTHA (with the caveats mentioned above).
One typical product of a PTHA analysis is a “hazard curve” that plots the annual probability that some quantity of interest exceeds a threshold as a function of that threshold. These are similar to the plots shown above, but with annual probability on the vertical axis and require additional assumptions and a slightly more complicated set of formulas to compute.
For more discussion and an illustration of how a hazard curve could be
computed, see
HazardCurveDemo,
rendered from the notebook geoclaw_multirun/HazardCurveDemo.ipynb
in the repository.
Extent of inundation and maximum depth¶
The maximum water depth at each grid point on a 1/3" grid covering the study area was computed over the 45 minute GeoClaw run performed for each source. Plots of these can be found at: fgmax_plots