Coastal Subsidence in Cape Canaveral, FL, and Surrounding Areas: Shallow Subsidence Induced by Natural and Anthropogenic Processes
Summary
Cape Canaveral, located on the east coast of Florida, is renowned for its significant role in space exploration and research. This iconic site, home to NASA’s Kennedy Space Center and Cape Canaveral Space Force Station, has been the launchpad for countless missions that have significantly advanced our understanding of space. The area hosts critical infrastructure including launch complexes, vehicle assembly buildings, and advanced tracking systems. These assets represent billions of dollars in investments and irreplaceable scientific resources. However, the long-term stability of this critical area is increasingly at risk of flooding caused by eustatic sea-level rise and vertical land motion (VLM). Pre-InSAR analyses, including precise leveling and sea-level measurements, reported subsidence rates of 4-9 mm/year (Holdahl & Morrison, 1974; Brown & Oliver, 1976), while contemporary InSAR analyses reported subsidence rates of 3-5 mm/yr (Ohenhen et al., 2024). Although the region is experiencing multi-decadal subsidence, the underlying causal factors remain poorly understood.
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This study area is located on the east central Florida coast and is part of the Atlantic Coastal Complex. It consists of three predominant geomorphic features each separated from the other by the Indian River Lagoon (IRL) and Banana River (BR), respectively: (1) Peninsular Mainland, (2) Merritt Island, and (3) Cape Canaveral (Figure 2). The Atlantic Coastal Ridge is present along the peninsula’s mainland shoreline. It is composed of a mixture of Pleistocene quartz sand and shell (unit Qa—Figure 3a), locally consolidated as coquina and part of the Anastasia Formation that is present along most of the east coast of Florida. The formation is about 5–20 m thick, with a local topographic relief of as much as 10 m at the Indian River Lagoon shoreline. The Anastasia grades westward into undifferentiated Quaternary quartz sand and shell (unit TQsu—Figure 2a) that is locally overlain by Holocene sediment (unit Qh—Figure 3a) associated with the St. Johns River basin. Seaward of the mainland is a cuspate foreland consisting of Pleistocene (Merritt Island) and Holocene (Cape Canaveral) beach-ridge complexes. The origin of Merritt Island and Cape Canaveral has been the subject of considerable scientific debate. Early hypotheses suggested that the formation was controlled by antecedent topographic relief created by a resistant bedrock formation or an underlying structural feature. Subsequent research suggested that the Holocene beach-ridge complex was created by converging littoral drift cells. Most recent research has suggested that the cuspate foreland is an abandon paleo-delta of the St. Johns River. However, to date, the debate over its origin has yet to be resolved.
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Methods
Multi-Temporal InSAR Data Analysis:
The multi-temporal InSAR analysis was applied to Sentinel-1 data to detect land subsidence. The ISCE-2 topsStack processor facilitated the co-registration of SAR scenes and the creation of interferograms stack with 5 nearest neighbor connections. The application of a multi-look factor of 18 in the slant range and 6 in the azimuth direction yielded a ground pixel resolution of 90 m by 90 m. The Copernicus GLO30 digital elevation model (DEM) was used to remove the topographic phase component from the interferograms. The Miami InSAR time series software in Python (MintPy) was used to apply the small baseline subset (SBAS) approach on the interferogram network. Bridging and phase closure methods were implemented for correcting phase unwrapping errors. A weighted least-squares (WLS) inversion was performed to derive the line-of-sight (LOS) velocity for each pixel. The stratified tropospheric delay was corrected using the ERA5 reanalysis model from the European Centre for Medium-Range Weather Forecasts with the PyAPS software. A temporal coherence threshold of 0.80 was applied in the resulting velocity map to mask unreliable pixels.
Post-Processing of the GNSS Data:
The GNSS daily solutions produced by the Nevada Geodetic Lab (NGL) enable us to calculate the site velocities of the four sites based on the vertical displacement time series. We post-processed the vertical displacement data to remove statistical outliers and correct for step discontinuities.
Leveling Data Analysis:
Processing the precise leveling data was challenging because the data were acquired along different traverses in different years and rarely repeated measurements along the same traverse of benchmark stations. Nevertheless, we identified pairs of benchmark stations that were surveyed multiple times. Such pairs allowed us to calculate localized subsidence, in which one benchmark was used as a reference point.
Results
InSAR processing of the July 2016 to June 2024 Sentinel-1 data revealed a patchy and heterogeneous subsidence pattern (Figure 1-(i)). The negative values indicate subsidence, and positive values indicate an uplift. In general, the Cape Canaveral infrastructure (e.g., administrative buildings, hangars, and support facilities) exhibited no significant vertical movement. However, InSAR analysis identified three localized subsiding areas located in the western, central, and southeastern parts of the study domain (marked by white triangles in Figure 1-(ii)). Subsidence in the western area is attributed to organic soil oxidation in wetlands (Figure 2), in the central area to infrastructure development (Figure 3), and in the southeastern area to the natural compaction of young siliciclastic sediments (Figure 4).
Figure 1. (i) InSAR-derived vertical velocity map of the study area for the period 2016-2024; (ii) ) Zoomed-in view of the InSAR-derived vertical velocity map for the area outlined in (i), highlighting localized subsiding areas in Cape Canaveral with white triangles; (b–d) vertical displacement time series plots for the localized subsiding areas, corresponding to the white triangles on the map. 
Figure 2. (a,b) Aerial imagery of the localized subsiding area in the western part of Cape Canaveral marked by the white triangle in Figure 1-ii, showing land cover changes over the past 74 years in white ellipses and its relations to the observed land subsidence; (c) localized subsidence detected using InSAR time series analysis. 
Figure 3. (a,b) Google Earth imagery from 2015 and 2018 showing runway expansion within the white ellipses; (c) localized subsidence detected using InSAR time series analysis. 
Figure 4. (a–c) Google Earth imagery from 1994, 2004, and 2024, highlighting the corresponding scatterer on the ground within the white ellipses; (d) localized subsidence detected using InSAR time series analysis.
In Cape Canaveral, GNSS stations CCV5 and CCV6 indicated ongoing subsidence with vertical velocity rates of -2.49 ± 0.32 mm/yr and -2.68 ± 0.78 mm/yr, respectively (Figure 5 (a) & (b)). In contrast, stations in the Peninsular Mainland exhibited low VLM rate: station TTVL showed 0.10 ± 0.15 mm/yr, while station COKO recorded -0.81 ± 0.10 mm/yr (Figure 5 (c) & (d)).
Figure 5. Comparison of GNSS-derived vertical displacement time series (blue) and Sentinel-1 InSAR-derived displacement time series (red). (a,b) Stations CCV5 and CCV6 at Cape Canaveral; (c,d) stations TTVL and COKO on the Peninsular Mainland. Publications
Sharma A, Wdowinski S, Parkinson RW. Coastal Subsidence in Cape Canaveral, FL, and Surrounding Areas: Shallow Subsidence Induced by Natural and Anthropogenic Processes. Land. 2025; 14(4):735. https://doi.org/10.3390/land14040735