Hot Springs

http://Gulf%20of%20Gera%20Hot%20Springs

Gulf of Gera Hot Springs

http://Polichnitos%20Hot%20Springs

Polichnitos Hot Springs

http://Eftalou%20Hot%20Springs

Eftalou Hot Springs

Not far beneath the surface of Lesvos there are still large concentrations of hot magma. These act as vast heaters, warming water which penetrates the crust to a considerable depth. When it approaches the magma chamber, the meteoric water is heated and comes up through the surface of the Earth via thermal springs.

The most important thermal springs on Lesvos are at Polichnitos, Lisvori, Thermi, Therma at Geras gulf, Eftalou and Argenos.

Polichnitos Hot Springs

The Polichnitos hot springs reach a temperature of 87,6οC, making it the warmest natural spring in Europe. The hot water circulating underground approaches 400οC. These springs gush up through ignimbrites which are the most recent volcanic rocks on Lesvos.

There are many hot springs which are particularly abundant during the rainy season. An intense but small geothermal anomaly, as well as a shallow geothermal aquifer (up to 92.5oC ) has been observed In the region. The geologic background of crystalline carbonate rocks, which appears near the ground surface, constitutes a good reservoir of geothermal fluids.

The hot springs of Polichnitos are rich in sodium chloride. In comparison with seawater however, the springs contain 3 times less sodium chloride. It is believed there is some seawater intrusion into the springs, approximately 30%.

The rocks where the hot springs well up feature shades of red and yellow due to deposits of iron oxide such as limonite and hematite.

The creation of the thermal springs of Polichnitos is connected to the intense volcanic activity which occurred in the Northeast Aegean 21.5 – 16.5 million years ago. The presence of a large magma chamber in the crust under the island of Lesvos still contains concentrations of hot magma not far below the surface. These concentrations act as giant heaters to the rainwater when it seeps down through the crust. The heated water then moves back up to the surface through faults and fissures finally emerging as thermal springs. During its travels through the rocks, the water is also enriched with metallic elements, thus granting the springs their therapeutic properties.

Gulf of Gera Hot Springs

The “Therma” hot springs gush up in Neogene sediments (which include clay and sandstone strata) along the great NW-SE fault which defines the eastern shore of the gulf. This fault has an impressive fault scarp. With a temperature of 39,7οC, these sodium chloride springs contain ammonium chloride, potassium nitrate, calcium chloride, magnesium chloride etc.

The creation of the thermal springs is connected with the intense volcanic activity which occurred in the Northeast Aegean 21.5 – 16.5 million years ago, due to the subduction of the African tectonic plate under the Eurasian.  When the subducting African plate reached a depth of tens of kilometers, the rocks of the oceanic crust melted. The liquid magma that was created was lighter than the surrounding materials of the asthenosphere resulting in its upward movement. When it reached the surface it created the large volcanoes of Lesvos: the Vatoussa, the Lepetymnos, the Agra, the Anemotia and the Messotopos volcanoes. Today this subduction occurs south of Crete and the Lesvos’ volcanoes aren’t active anymore. The presence of a large magma chamber in the crust under the island of Lesvos still contains concentrations of hot magma not far below the surface. These concentrations act as giant heaters to the rainwater when it percolates down through the crust. The heated water then moves back up to the surface through faults and fissures finally emerging as thermal springs. During its travels through the rocks, the water is also enriched with metallic elements, thus granting the springs their therapeutic properties.

Lisvori Hot Springs

Near the church of Agios Ioannis and the Glifia torrent, thermal water with a temperature of 69οC and a radioactivity of 2.5 Mache wells up between the volcanic conglomerates and volcanic tuffs. The hot springs of Lisvori are rich in sodium chloride.

The origin of the Lisvori thermal springsis connected to the intense volcanic activity which occurred in the Northeast Aegean 21.5 – 16.5 million years ago. The presence of a large magma chamber in the crust under the island of Lesvos still contains concentrations of hot magma not far below the surface. These concentrations act as giant heaters to the rainwater when it seeps down through the crust. The heated water then moves back up to the surface through faults and fissures finally emerging as thermal springs. During its travels through the rocks, the water is also enriched with metallic elements, thus granting the springs their therapeutic properties.

Argenos Hot Springs

The coastal hot springs of Argenos, known as the “Megala Therma” (large springs), are situated both on land and in the sea. The sodium chloride spring water has a temperature of 86οC and contains low levels of carbonates and magnesium and higher levels of calcium and sulphates in comparison with the Polichnitos hot springs. The springs emerge through highly fractured volcanic rocks.

The creation of the thermal springs is connected to the intense volcanic activity which occurred in the Northeast Aegean 21.5 – 16.5 million years ago. The Argenos hot springs well up through andesitic tuffs and conglomerates associated with the intense volcanic activity of Lepetymnos, the largest volcanic center on Lesvos. The volcano of Lepetymnos is no longer active. However, the presence of a large magma chamber in the crust under the island of Lesvos still contains concentrations of hot magma not far below the surface. These concentrations act as giant heaters to the rainwater when it seeps down through the crust. The heated water then moves back up to the surface through faults and fissures finally emerging as thermal springs. During its travels through the rocks, the water is also enriched with metallic elements, thus granting the springs their therapeutic properties.

Hot Springs of Loutropolis Thermi

The thermal springs of Loutropolis Thermi have been used since ancient times for curative purposes. At a temperature of 49,9οC, the ferrous hot spring water is very salty due to seawater mixing with hydrothermal water.

The existence of these hot springs is the result of the intersection of two deep faults with WNW – ESE and NNW – SSE orientations which facilitate water moving upwards from great depths. A mixture of rainwater and seawater percolates down into the crust, where it is enriched with minerals and heated. Then it moves up once again through cracks to more shallow depths or up to the surface where it is mixed again.

The creation of the thermal springs is connected to the intense volcanic activity which occurred in the Northeast Aegean 21.5 – 16.5 million years ago. The presence of a large magma chamber in the crust under the island of Lesvos still contains concentrations of hot magma not far below the surface. These concentrations act as giant heaters to the rainwater when it seeps down through the crust. The heated water then moves back up to the surface through faults and fissures finally emerging as a thermal spring. During its travels through the rocks, the water is also enriched with metallic elements, thus granting the springs their therapeutic properties.

Eftalou Hot Springs

The sodium chlorinated radioactive spring water of Eftalou gushes out of the volcanic rocks of Lepetymnos along tectonic discontinuities. The water temperature is 43,6οC to 46,5οC. This is the most radioactive spring on the island with a reading of 14.7 Mache (harmless to bathers).

The creation of the thermal springs is connected to the intense volcanic activity which occurred in the northeast Aegean 21.5 – 16.5 million years ago. The Eftalou hot springs well up through andesitic tuffs and conglomerates associated with the powerful eruptions of Lepetymnos, the largest volcanic center on Lesvos. The volcano of Lepetymnos is no longer active. However, the presence of a large magma chamber in the crust under the island of Lesvos still contains concentrations of hot magma not far below the surface. These concentrations act as giant heaters to the rainwater when it seeps down through the crust. The heated water then moves back up to the surface through faults and fissures finally emerging as a thermal spring. During its travels through the rocks, the water is also enriched with metallic elements, thus granting the springs their therapeutic properties.

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