Category:HAZUS Technical Guides

In working on a final project for a cartography class, I decided to do an AEBM analysis of the Sugar House community in Salt Lake City. This area is made up of about 20 census tracts and is known for its high percentage of URMs.

I learned a few lessons that I would like to share with the HAZUS development team, users and other interested parties:

1) Using a modified parcel database as a building inventory for AEBM:

To “trick” AEBM into considering a single parcel to be equivalent with a single building (disregarding detached structures on a property) I reduced 21,430 parcels to 11,496 parcels based on their unique addresses. I also had access to a portion of Salt Lake County assessor database which gives “exterior wall type” among other essential attributes. In consultation with Dr. Larry Reavely (one of Utah’s pre-eminent structural engineers who has worked extensively in seismic structural design, we came up with a simple algorithm to convert exterior wall types (from the assessor data) into FEMA building types (that AEBM requires) based on construction year and local practice for my study region. This data transformation gave me enough to feed to AEBM to get a Level 3 earthquake loss estimation of my community.

2) You may be aware that there are some defects in HAZUS-MH MR3 that prevent the AEBM analysis results from being mapped properly in a GIS. Specifically, the lat/lng coordinates are truncated so that the results do not project to the same coordinates as the input. This defect makes it especially difficult to map the AEBM results on the same map as the initial building inventory. But, as luck would have it, I noticed a pattern in the naming convention of the output data set. Each row’s eqAebmId is prefaced with “US” and a certain number of leading zeros. By adopting this same naming convention of my input data, the AEBM did not kept the ID and I was able to relate the eqAebmId with my initial parcel ID acting as the AEBM building name. By exporting the AEBM results to a shapefile, I was able to import them again into ArcGIS and join my input with the AEBM output, thus bypassing the incorrect AEBM geometry and incorporating the values of the AEBM results into my parcel attribute table. The end result (for my project) is a choropleth map showing total economic loss.

Take aways:

* It is my intention to spend some time in December to write up this process as a technical note for HAZUS MR3 users interested in doing an earthquake analysis and mapping the results.

* I am also interested in your reaction to my use of a modified parcel database (combined with county assessor data) as input to the AEBM analysis.

* When the map is complete (due on Wed this week) I will send along a copy if you are interested. It will be a large format (36 x 42 inches) but the PDF is only about 2MB

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• HAZUS Technical Guides