Abstract
The main purpose of this study is to comparatively assess the susceptibility of earthquake-triggered landslides in the island of Lefkada (Ionian Islands, Greece) using two different statistical analysis models, a bivariate model represented by frequency ratio (FR), and a multivariate model represented by logistic regression (LR). For the implementation of the models, the relationship between geo-environmental factors contributing to landslides and documented events related to the 17th November 2015 earthquake was investigated by geographic information systems (GIS)-based analysis. A landslide inventory with events attributed to the specific earthquake was prepared using satellite imagery interpretation and field surveys. Eight factors: Elevation, slope angle, slope aspect, distance to main road network, distance to faults, land cover, geology, and peak ground acceleration (PGA), were considered and used as thematic data layers. The prediction capability of the models and the accuracy of the resulting susceptibility maps were tested by a standard validation method, the receiver operator characteristic (ROC) analysis. Based on the validation results, the output map with the highest reliability could potentially constitute an ideal basis for use within regional spatial planning as well as for the organization of emergency actions by local authorities.
Highlights
Landslides are related to a great number of human losses and economic damages (Table 1).One of the major mechanisms by which a landslide can occur is triggering due to earthquakes [1].Over the last two decades, strong earthquakes have triggered the occurrence of landslides in many islands of the Ionian Sea (2003 in Lefkada, 2014 in Kephalonia, 2015 in Lefkada, 2018 in Zakynthos).This part of Greece can be characterized as a high-seismicity region, prone and vulnerable to earthquake-triggered landslides.In order to determine the most fragile landslide areas under the influence of a given earthquake in the future, it is important to indicate these areas through landslide susceptibility assessment and mapping [2]
Based on the frequency ratio (FR) model, the factor categories that presented the highest correlation with the occurrence of landslides triggered by and logistic regression (LR) models
In terms of acquisition of this knowledge, the present study focused on the creation of a reliable landslide susceptibility map that will spatially define the landslide occurrence for the island of Lefkada
Summary
Landslides are related to a great number of human losses and economic damages (Table 1).One of the major mechanisms by which a landslide can occur is triggering due to earthquakes [1].Over the last two decades, strong earthquakes have triggered the occurrence of landslides in many islands of the Ionian Sea (2003 in Lefkada, 2014 in Kephalonia, 2015 in Lefkada, 2018 in Zakynthos).This part of Greece can be characterized as a high-seismicity region, prone and vulnerable to earthquake-triggered landslides.In order to determine the most fragile landslide areas under the influence of a given earthquake in the future, it is important to indicate these areas through landslide susceptibility assessment and mapping [2]. Over the last two decades, strong earthquakes have triggered the occurrence of landslides in many islands of the Ionian Sea (2003 in Lefkada, 2014 in Kephalonia, 2015 in Lefkada, 2018 in Zakynthos). This part of Greece can be characterized as a high-seismicity region, prone and vulnerable to earthquake-triggered landslides. In order to determine the most fragile landslide areas under the influence of a given earthquake in the future, it is important to indicate these areas through landslide susceptibility assessment and mapping [2]. A landslide susceptibility map gives an indication of “where” future landslides are likely to occur over a region on the basis of local geo-environmental conditions. The knowledge about the spatial probability of their occurrence is very important for hazard management and mitigation, and safe planning [3]
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