Global Fatal Coastal Landslides

Reiss, Malia N; Young, Adam P; Carilli, Jessica

doi:10.5194/egusphere-2026-96

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https://doi.org/10.5194/egusphere-2026-96

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19 Jan 2026

| 19 Jan 2026

Status: this preprint is open for discussion and under review for Natural Hazards and Earth System Sciences (NHESS).

Global Fatal Coastal Landslides

Malia N Reiss, Adam P Young, and Jessica Carilli

Abstract. Coastal cliffs shape the world’s coastlines, providing areas of beauty, habitat, scientific discovery, and recreation. However, as erosional features, coastal cliffs can also pose fatal hazards. This paper presents a database of global fatal coastal landslides from public databases and media articles. In total, the coastal landslide database includes 292 fatalities resulting from 114 landslide events from 1927–2024. Landslide events occurred in 32 countries, with the most events in Spain (20), the United States (19), France (14), and the United Kingdom (10), and include two 10-event hot spots on Reunion Island, France, and San Diego County, California, USA. Most fatalities occurred in temperate regions, with about half of events occurring during months with above average precipitation (and half below), differing from databases that include non coastal fatal landslide events driven largely by rainfall. The database is likely incomplete in part from reporting bias, and the analysis presented here should be interpreted with caution. However, the present results suggest that the timing of coastal fatal landslides may be influenced by (a) elevated rainfall causing reduced cliff stability, leading to more failures in wet seasons and (b) time periods of increased tourism and recreational beach activity, exposing more people to coastal cliff failure hazards in relatively dry seasons. The results can help inform beach hazard management.

Received: 07 Jan 2026 – Discussion started: 19 Jan 2026

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this paper. While Copernicus Publications makes every effort to include appropriate place names, the final responsibility lies with the authors. Views expressed in the text are those of the authors and do not necessarily reflect the views of the publisher.

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Malia N Reiss, Adam P Young, and Jessica Carilli

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RC1:
'Comment on egusphere-2026-96', Anonymous Referee #1, 26 Jan 2026 reply
The paper by Reiss et al. explores a database of 114 fatal coastal cliff collapses over 97 years. Geographic hotspots of coastal landslides were identified, including San Diego County (USA) and Réunion (France). The timing of fatal landslides was further analysed in relation to precipitation in the region during the month of the event. Around 50% of the events occurred during “dry” months, partly because more people were on beaches during these periods. The findings highlight the importance of accounting for both environmental effects on cliff collapse hazards and human behaviour and displacement patterns in coastal hazard management efforts.
The paper is well-written and structured. However, some major points remain to be clarified and further analysed. These are the following general comments:
The title seems misleading, as the paper does not address all coastal landslides but only coastal cliff collapses. Other types of landslides impacting the coast, such as inland slides reaching the coast, debris flows or tsunami impacts from distant slides, were excluded from the database. In addition, the term “global” might be considered overly confident given clear and correctly stated sampling biases.

The distinction between coastal cliff collapses and other landslide events is sometimes difficult. In addition, large landslides impacting the coast or generating fatal tsunamis are excluded from the database (rule number 2, lines 66-68), even though they are coastal landslides and important events for regions such as Alaska and Greenland. A better explanation of why to exclude such landslides and of how to categorise borderline cases is necessary.

While an effort has been made to include more languages than English alone, the database might be skewed towards regions with better records and media access to remote locations, rather than global coverage. It is likely that many events in the global South were not accounted for, particularly single-victim events, events in the typhoon and monsoon seasons, and that additional languages should be included in a global database. An alternative might be to exclude parts of the world where coverage is likely to be too poor.

114 events are a relatively small statistical population. That makes it difficult to draw global conclusions about landslide triggers, particularly because only fatal landslides are considered. Classic statistical tests and measures are not presented for the monthly rainfall analysis. Such tests should account for the link between rainfall and human presence, as these are not independent variables.

The approach of binning each event by monthly total precipitation seems too simplistic. An event at the start of a month would take into account rainfall in the weeks following the event, not in the weeks preceding it. A better approach would be to use the 1-month rainfall total at the time of the event rather than the calendar-month rainfall total. In addition, using the same approach, different rainfall durations (e.g., 3 days or 1 week) could be evaluated, which might be more appropriate for shallow landslides. With this approach, it might be possible to draw more robust conclusions about the effects of intense rainfall events during the dry season. Similarly, at some tourist locations, we could expect more visitors on weekends. A test of landslides grouped by day of the week, during the tourist season and the off-season, might yield new insights for the identified local hotspots.

Additional minor comments are:
Since most events occur in temperate climates and the Northern Hemisphere, the results might not be applicable to tropical, arid, or polar coasts, where landslides may exhibit different temporal dynamics. Once again, this point challenges the “global” approach and should be at least mentioned.

The tools for translating keywords and searching media online were not clearly specified. Were AI tools involved? If yes, which ones?

Thresholds to consider a correlation significant are not discussed.

In addition, I note the following technical corrections:
The lack of an accent for Réunion Island, which should be added.

GDP units seem not correct. The sources for the GDP data are missing. GDP per capita would probably be more appropriate for this analysis.

Figure 1: Black boxes should be removed.

Figure 2: The title should be removed above the figure.

Figure 3: A large number of countries seem to have a single landslide event. This might influence the statistics. Countries with no landslides could be included.

Figure 8 should include a second panel, with the same analysis for Réunion Island.

In the database, the “Victim” category is unclear, the “Tourism season” category is always left empty, and the “Distance from coast” category lacks units and appears binary.

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Citation: https://doi.org/10.5194/egusphere-2026-96-RC1

Malia N Reiss, Adam P Young, and Jessica Carilli

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https://doi.org/10.5194/egusphere-2026-96-supplement

Malia N Reiss, Adam P Young, and Jessica Carilli

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Short summary

Globally, coastal cliffs can pose fatal hazards. We present a global fatal coastal landslide database, with 114 fatal events that killed 292 people from 1927–2024. Using this database, we found that deaths from coastal landslides are partly associated with elevated rainfall, and partly associated with dry periods with elevated human beach activity. These results can help inform beach hazard management.


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