Virtual California (VC), Earthquake Science

VC (Rundle et al., 2002) is earthquake simulation model for the California. The simulation takes into account the gradual movement of faults and their interaction with each other. It includes 650 segments representing the major fault systems in California, including the San Andreas Fault responsible for the 1906 San Francisco earthquake (Donnellan, 2004).

VC is a program to simulate interactions between vertical strike slip faults using an elastic layer over a viscoelastic half-space. It relies on fault and fault friction models.

At the application, or simulation level, VC has a two-phase run. In the first phase, the user runs the application by giving required parameters and gets the result for the best cost. The definition of cost and it‟s calculation are application specific and defined at (Rundle et al., 2003). If the user likes the returned cost, he runs the second-phase with the returned cost and some other parameters given through VC GUI to get the forecast values (Donnellan et al., 2003). The result forecast values are played in a movie streams (see the below sample run with JMF -Java Media Framework- client) ("JMF," 2008). Each frame in the stream is actually a three-layer structured static map.

There is no additional component needed besides the components explained before.

a. GIS users interact with the system through the user interface provided by WMS Client and/or GIS Portal. GIS user enters the parameters to get specific region of the world as a map from the WMS server.

b. WMS Client makes a request to the WMS on behalf of the user. It submits a request to the WMS Server by selecting desired features and an area on the map. WMS returns a map in the form of an image or an exception in case of an error. c. In order to create user specific maps, WMS Server forwards user‟s request to the

WFS to get requested feature data. WFS decodes the request, queries the database for the features and receives the response. Feature data is returned to the WMS server as a set of feature collections.

The above three steps are common to any application to create a display in the form of maps. Below, we list VC specific process flow to overlay VC output as another layer on top of the map image created through the processes listed above.

1. After receiving and displaying the maps returned from the WMS server, the user starts running VC simulation code through GIS Portal. The GIS Portal provides the user with the ability to setup the experiment and the parameters associated with each set of run.

2. The user sets application specific parameters such as bounding box and the time frame of the experiment‟s data. These values are bundled as script execution parameters and sent to the HPSearch engine.

3. The HPSearch engine then runs the script with the specified parameters. For each run, the service selects an instance of the VC runner service and initializes it.

4. Once all initialization is done, the HPsearch engine invokes the streaming WFS service.

5. The WFS sends the requested seismic records to the VC Runner service. The VC Runner service filters the input data. This step also converts date to float format. Once all the data has been accumulated, the VC Runner service runs the VC code on the input data using the input parameters. Usually each instance of the VC Runner service will work with different set of parameters.

6. The output of the VC runs is stored in output files.

7. On completion the VC runner stores the best cost that was computed per run in the context service. The best cost is the smallest value and will be used for determining the set of input parameters that needs investigated further.

8. The services then notify the HPSearch engine of the completion

9. HPSearch engine queries the context service to retrieve the best cost and then again writes to the context service the location of the output file that corresponds to the best cost.

10.The WMS constantly monitors the context service to see if the computation was completed. Once the computation is complete, it retrieves the location of the output file that corresponds to the best cost.

12.Depending on the data and the geophysics application GIS Portal superimpose returned data as a new layer or makes some animated map or movie streams. In case of VC application, returned output data is multi-casted to a specific IP and port as movie streams.

Outcomes from the VC demo are map movies like animations. Links to a sample movie for Virtual California is listed below.

For this sample case, there are 1144 records in the output file returned by VC Runner Service shown in Figure 27.

http://complexity.ucs.indiana.edu/~asayar/gisgrids/docs/VCDemo_03.swf (Flash version)

a _b 2 1 7 9 1 0 11 8 6 5 4 3 WSContext Service HPSearch Engine VC Runner Service VC Runner Service VC Runner Service VC Runner Service Output File Output _File Output

File Output _File WMS Client / GIS Portal WMS c D B WFS DB User Browser

http://complexity.ucs.indiana.edu/~asayar/gisgrids/html/work/VC_01.avi (Avi format)

VC Runner Services See them in Figure 27

VC Map-Movie creation interface. Choose periodicity of time series data framework play