GRSG 35th Conference 2024 Abstract

Title: Understanding multi-hazard cascades from the Türkiye 2023 earthquakes

Author: Holly Hourston

Organisation: British Geological Survey

The 2023 Kahramanmaraş earthquakes of the 6th of February resulted in a death toll of over 57,000 people across Türkiye and Syria. The cascading and compounding multi-hazards connected to this event are largely attributed with this tragically high death toll, including floods and landslides, to name some of which. The meteorological hazards compounding this event include extreme cold, snow and stormy weather, which inundated homes, key infrastructure and the humanitarian effort. Specifically, the factors dominating post-seismic landslides and their compound hazard together with floods over such a large area are difficult to map together.

We will address these challenges in the ongoing ESA-funded project underway between the British Geological Survey and several partner institutes, “Advancing knowledge of Multi-Hazard Events and their Impacts” (AMHEI), in which we aim to develop a novel AI model to better understand the relationship between the compounded hazards of landslides, flooding and earthquakes. We also hope to improve our understanding of what the most critical factors in the exacerbation of post-seismic multi-hazards are and to improve our capabilities for monitoring seismic environments, through the development of a post-seismic multi-hazard database of the Kahramanmaraş earthquake event.

In this contribution we will cover preliminary results of our internet-extracted database of multi-hazard events, with relevant satellite-derived data, to better understand the spatio-temporal impact chain of events triggered by the earthquakes. We will also present on the interplay of multi-hazard interactions in seismic zones in a geospatial context, and to provide EO-backed evidence from Interferometric Synthetic Aperture Radar (InSAR) analyses of landslides or surface ruptures reported in the database.

We have constructed a multi-hazard database of the significant geological and hydrometeorological events in the 5 years prior to the February 2023 earthquake event in the worst-affected provinces of Türkiye, and another database of those immediately following the earthquakes, to produce two databases of natural hazards. The data was gathered via a literature search of social media posts, news reports from a variety of sources, academic literature and EO press releases, with any mentions of estimated death toll, number of injuries and/or infrastructure damage noted. The event location and date (and time, if applicable) was recorded and any satellite imagery of the event attached.

Our initial analysis of the events suggests that there were three main hazards that culminated in this violent and long-lasting event- firstly, the country was experiencing heavy rainfall before February 6th 2023, particularly in Hatay, one of the worst-affected provinces. Then, the pair of earthquakes on February 6th started a chain of events, including thousands of aftershocks, tsunami, rockfalls, landslides, and flooding. Thirdly, a snowstorm began, bringing sub-zero temperatures and several inches of snow, hindering rescue efforts and aid reaching where it was most needed. The cascading hazards from these three main hazards are listed in our database and summarised into detailed temporal multi-hazard networks by province. Our next step is to integrate with the post-seismic landslide inventory generated from Sentinel-2 through the AMHEI project, and the InSAR deformation derived from ALOS.

Overall, our database provides spatio-temporal insights into the impacts of the Türkiye earthquakes, and displays the developments through time of the various hazards which caused delays in news updates, accurate death tolls, rescue attempts and incoming aid to help the people most affected by this disaster. From further analysis of this database, we will identify secondary hazards which indirectly caused further loss of life, injury, and/or economic damage, and to identify preconditions for future multi-hazard chains for the East Anatolian Fault zone and other similar seismic environments.