One major concern is the increased risk of Glacial Lake Outburst Floods (GLOF), which have in the past had great effect on lives and property. Glacier meltwater left behind by the retreating glacier is often held back by moraines that can be unstable and have been known to collapse if breached or displaced by earthquakes, landslides or avalanches. If the terminal moraine is not strong enough to hold the rising water behind it, it can burst, leading to a massive localized flood. The likelihood of such events is rising due to the creation and expansion of glacial lakes resulting from glacier retreat. Past floods have been deadly and have resulted in enormous property damage. Towns and villages in steep, narrow valleys that are downstream from glacial lakes are at the greatest risk. In 1892 a GLOF released some of water from the lake of the Tête Rousse Glacier, resulting in the deaths of 200 people in the French town of Saint-Gervais-les-Bains. GLOFs have been known to occur in every region of the world where glaciers are located. Continued glacier retreat is expected to create and expand glacial lakes, increasing the danger of future GLOFs.