World Water Day with a Spotlight on Seismicity - Greece
The critical role of water as a renewable energy source, via the operation of hydroelectric power, attracts also the attention of geohazard analysis due to the triggered seismicity caused by reservoir impoundment. In Greece, there is a number of hydroelectric power plant complexes located around the greatest rivers of the country amounting to about 9% of the total production of the Public Power Corporation, while the artificial lakes provide water for some large cities and support a healthy ecosystem. At the same time, reservoir impoundment is known to trigger seismic responses, usually in the form of weak and moderate magnitude earthquakes, but can be also related to the triggering of strong ones.
In 1966, immediately after the impoundment of the Kremasta lake, a destructive earthquake of M>6.0 occurred, leading to an intense aftershock activity in an area that was seismically active but had not experienced a M6.0 earthquake for over 200 years. Similarly, the reservoir impoundment of three lakes in the Aliakmonas river complex between 1974 and 1985 led to an increase of seismicity, and in 1995, an MS6.6 earthquake occurred about 20 km away from the Polyphyto dam in an area of historically low seismicity rates, that had not experienced such a magnitude for centuries. Both earthquakes led to loss of life and thousands of destroyed or severely damaged houses and infrastructure. Cases like those highlight the fine balance between the benefits of clean hydropower energy and geohazard risk management when working towards a sustainable and environmentally responsible energy future.
Anastasios Kostoglou (Greek)– Research Assistant (IGF – PAS)