Are Central Oklahomans Fixing their Tornado Sheltering Problem?

Most homes and businesses in the state of Oklahoma are built on slab concrete foundations.  Consequently, these structures, when built to standard residential building codes, lack an inherent designated shelter from tornadoes.  Some builders advertise building practices that go beyond the standard residential building codes, and cities are beginning to adopt upgrades to their building codes in response to being directly impacted by damaging tornadoes.  However, in some instances it is unclear if these enhancements result in the establishment of a continuous load path, so it is questionable how the additional structural strength will hold up in the most destructive areas of violent tornadoes.  Alternatively, for a few thousand dollars or with the help of local, state, or federal funding programs, people can purchase an above- or below-ground storm shelter for their home.  But to what extent are these practices occuring?

This presentation will discuss a recent and rather dramatic proliferation of reported storm shelter installations occurring within the city of Norman, Oklahoma and nearby communities.  For example, approximately two thirds of all reported storm shelters within the city of Norman have been installed since May of 2013, when recurring episodes of violent tornadoes impacted central Oklahoma.  In particular, the evening of 31 May 2013 was associated with a mass exodus of residents attempting to flee the Oklahoma City metropolitan area.  At that time, about 1 out of every 13 homes in Norman had a reported storm shelter.  Now, this ratio is close to 1 out of 4.  Additionally, there is clear geospatial inhomogeneity among neighborhoods with reported storm shelters, which raises further questions about the factors driving the apparent societal response to prolific tornado events occuring within the Oklahoma City metro area.  This presentation will include geospatial and temporal analyses of the reported storm shelter observations to estimate the current state of sheltering resiliency within central Oklahoma communities in relation to potential contributing factors and implications for the future.