Geospatial patterns of urban development and earthquake retrofits in Los Angeles, CA

Abstract

The questions of equity and disproportionate distribution of risk in relation to natural hazards have received growing attention that has been reflected (or is starting to reflect) in policies and mitigation plans. On the other hand, the urban landscape has been changing in response to community demands, which has raised questions of equity in another context. In this study, we look at Los Angeles County as the case-study landscape and ask whether the recent patterns of urban development and revitalization have been related to the investments in earthquake retrofits, and if so, what are the associations and contributing factors. To answer this question, we gathered data from census bureau American Community Survey, the LA Department of Building and Safety (LADBS), and LA Open Data Portal (LAOPD), and aggregated the data at the census-tract level. The analysis includes geospatial and statistical approaches using ArcGIS Pro, Python, and SPSS. We find a highly variable level of association between earthquake retrofits in residential buildings and the socio-demographics of the population, and a close relationship in areas of recently resuscitated neighborhoods in Los Angeles County. Additionally, the pattern of increased cripple wall retrofits among disadvantaged communities after the initiation of Earthquake Brace and Bolt program suggests the effectiveness of mitigation efforts.