2.4.7. Physics Based Ground Motions

This panel allows users to use the results of previously run physics based earthquake rupture simulations that generated suites of ground motions for the areas studied. As more datasets are made available, more options will be added to the options in the pull down menu.

2.4.7.1. M9 Dataset

With funding support from the National Science Foundation, a United States Geological Survey and University of Washington team studied the impacts of large magnitude, megathrust earthquakes on the Cascadia subduction zone as part of the M9 Project . The researchers used physics-based simulations to generate possible ground motions for the entire Pacific Northwest region during a magnitude-9 (M9) event. Broadband ground motions were developed from these M9 simulations for a number of grids (A, B, C, D, E, Y and Z), each corresponding to a particular combination of region and/or grid resolution.

Table 2.4.7.1.1 Title

Grid	Location	Grid Spacing	Latitude Range	Longitude Range
A	Pugent Sound	1 km	46.9 to 48.3	-123.2 to -121.1
B	Entire Area	20 km	40.3 to 48.6	-127.7 to -125.4
C	Portland, Oregon	1 km	45.2 to 45.9	-123.3 to -122.2
D	Vancouver, BC	1 km	49.0 to 49.4	-123.3 to -122.4
E	Victoria, BC	1 km	48.3 to 48.7	-123.9 to -123.2

M9 Grids

To use this M9 dataset the user inputs a number of options, grid type, latitude and longitude being the location for which the motions are sought, and numMotions for the number of motions desired at the location. The location on the users computer that the motions will be downloaded to for a staging area is specified by the user in tmp Directory, by default it is specified to be in the users Documents/EE-UQ/LocalWorkDir directory.

Once the user has entered the inputs they press the Get Motions button. This will start the download process in the background, i.e. behind the scenes. The download is being done in the background because the download process is painfully slow, a few minutes per ground motion. While the motions are downloading, the user can work on other parts of the interface. Should the user attempt to Run a simulation before the motions are finished downloading, a pop up window will appear informing the user that the run should be cancelled.

Fig. 2.4.7.1.1 M9 Interface