ABSTRACT

Rainfall associated with Hurricane María triggered more than 70,000 shallow landslides over a 6,400 km² area of Puerto Rico for a mean density of 11.2 slope failures per km². When compared to other single storm landslide inventories with similarly sized search areas in tropical and sub-tropical regions, HMA’s mean landslide density is eleven times greater than the average. This study relied on frequency and zero-inflated negative binomial regression analyses to explain the spatial variability of landslide densities induced by HMA in relation to soil, geologic terrane, land cover, total storm precipitation, slope, and elevation. Results show that landslide densities tended to be exponentially higher for those areas with the highest rainfall totals and greater on igneous intrusive and other non-limestone sedimentary geologic terranes. Additionally, maximum densities occurred on relatively moderate slopes of 35–50% and not on the steepest hillslopes. Although a resulting regression model over-predicts landslides at lower elevations and underestimates high landslide density areas, it provides an acceptable fit for the landslide densities at a 0.25 km² scale. The results presented here can guide future landslide susceptibility analyses to adequately contextualize the heterogeneity of landslide activity caused by extreme tropical cyclones in Puerto Rico and elsewhere.

摘要

与飓风玛丽亚有关的降雨在波多黎各6,400 平方公里^{2的地区引发了 70,000 多次浅层滑坡，平均密度为每平方公里 11.2 次斜坡崩塌2}. 与在热带和亚热带地区具有类似大小搜索区域的其他单一风暴滑坡清单相比，HMA 的平均滑坡密度是平均值的 11 倍。本研究依靠频率和零膨胀负二项式回归分析来解释 HMA 引起的滑坡密度与土壤、地质地体、土地覆盖、总暴雨降水量、坡度和海拔相关的空间变异性。结果表明，在总降雨量最高的地区，滑坡密度往往呈指数级增长，而在火成岩侵入岩和其他非石灰岩沉积地质地体中则更高。此外，最大密度发生在 35-50% 的相对温和的斜坡上，而不是最陡峭的山坡上。²规模。这里提供的结果可以指导未来的滑坡敏感性分析，以充分了解由波多黎各和其他地方的极端热带气旋引起的滑坡活动的异质性。