Scaling and exceedance probability of sinkhole collapse in evaporite karst (Dead Sea, Jordan)

Abstract. Quantitative analysis of sinkhole collapse hazard requires robust data in both space and time. It also needs a clear understanding of the factors and processes that contribute to observed sinkhole locations and dimensions. In many karst settings, these criteria are difficult to meet because of the millennia-long time scales over which sinkhole populations are generated and because of uncertainties around how geomorphological processes link to sinkhole dimensions. This study presents new data on the scaling and probability of sinkhole formation in evaporite karst on the eastern Dead Sea shore (Jordan). Several thousand cover collapse sinkholes have formed there in the past 40 years with minimal post-collapse modification. Genetic processes and timescales are thus well constrained. Utilising high-resolution satellite imagery (Pleiades, PNEO) from 2017–2024, integrated with prior datasets, we present an updated inventory of sinkhole occurrence, extent and dimensions through time over the period 1992–2024. The sinkhole number increased by 43 % from 1565 in 2018 to 2247 in 2024, reflecting a 22 % increase in the sinkhole-affected land area to c. 179610 m² (17.9 ha). Formation of new karst subsidence features has continued a northward and seaward advance, consistent with control from the decline of the Dead Sea base level. However, we also observed a localised revival in 2021–2022 of sinkhole formation in an area that had been apparently inactive since 2002. This combination of continued and renewed sinkhole formation poses significant challenges to agriculture, housing and infrastructure in the area. Sinkhole average diameters range from 0.8 to 72.9 m; their frequency follows a log-normal distribution, rather than a power-law. Representative annualised exceedance probabilities for formation of sinkholes with diameters greater than 5, 10 and 50 m are c. 70 %, 30 % and 0.5 % respectively. Exceedance probabilities show some dependence on sampling time interval and on the nature of near-surface materials in which sinkholes form. Given their log-normal size distribution, the Dead Sea cover collapse sinkholes are not scale-free; instead they are scale-bound by the evaporite karst system’s geometrical and mechanical properties.