The hot springs of Amasya province are gathered in three areas: Gözlek and Terziköy to the south-east of the provincial centre, and Hamamözü in the mountainous far west of the province. The Amasya mineral and energy inventory of the General Directorate of Mineral Research and Exploration (MTA) lists all three as geothermal fields. In each of them the natural outlets have a temperature between 37 and 40 degrees and a flow of 2 to 10 litres per second, while the boreholes drilled in the fields have yielded fluids with temperatures between 35.5 and 42.5 degrees and flows between 11.5 and 125 litres per second. Since these temperatures are too low for electricity generation, the waters are used directly for bathing, drinking and heating. The inventory gives the same three uses for all three fields: spa baths, spa facilities and greenhouse heating.

The Three Fields at a Glance

For each field the inventory gives separate values for the natural outlet and for the boreholes, and the difference between them reflects the geothermal situation of the region well. For many centuries the natural outlets were the only source people had; the boreholes have since increased the flow several times over in the same fields.

  • Gözlek: natural outlet 39 degrees and 2 litres per second; boreholes 35.5 to 40.5 degrees and 11.5 litres per second.
  • Terziköy: natural outlet 37 degrees and 10 litres per second; boreholes 37.2 to 40.1 degrees and a total of 43 litres per second.
  • Hamamözü (Arkut Bey): natural outlet 40 degrees and 2.8 litres per second; borehole 42.5 degrees and 125 litres per second.

In the inventory the potential of the boreholes is calculated by adding up the initial production flows of the wells. For this reason the thermal power of 3.84 megawatts given for the Hamamözü borehole is roughly sixty-five times the 0.059 megawatts of the natural outlet. The same table lists 0.034 megawatts for the natural outlet at Gözlek and 0.26 megawatts for its boreholes, and 0.08 megawatts for the natural outlet at Terziköy. The figures rest on the MTA geothermal inventories of 1996 and 2005 and on the 2001 work of the mining special expert commission for the Eighth Five-Year Development Plan, so they do not show the present operating state of the fields; they reflect measurements from the period in which those studies were made.

The Geological Ground

The rock assemblages exposed within the province of Amasya belong to the Sakarya Zone. According to MTA, the North Anatolian Fault passes through the north of the province near Taşova, and the Kırıkkale-Erbaa Fault passes to the south of Amasya; both are among the important active strike-slip faults of the region. The North Anatolian Fault is a right-lateral fault zone about 1,100 kilometres long, running from the vicinity of Lake Van to the Gulf of Saros, and it consists of many segments rather than a single fracture. Crushed rocks, cold and hot springs, small lakes and travertine formations are reported to occur together along the fault zone. MTA associates the emergence of the hot waters of Amasya with fault systems of this kind.

A doctoral thesis prepared at Istanbul Technical University by Mehmet Korhan Erturaç under the supervision of Okan Tüysüz draws the tectonic framework of this geography in detail. The thesis studies a broad area spread over the provinces of Amasya, Tokat and Çorum, bounded on the west by the 35th meridian, on the north by the main strand of the North Anatolian Fault and on the south by the Ezinepazar-Sungurlu Fault System, one of the branches of that fault. Called the Amasya Shear Zone, this area is a wedge-shaped deformation belt that begins at Niksar in the east and widens towards the west. Its width is about 10 kilometres in the east and reaches 100 kilometres in the west, while the activity and the offsets of the fault zones decrease westwards as they move away from the main strand. The zone lies within the Tokat Massif, which forms the eastern extension of the Sakarya Continent.

The rocks that make up the massif fall into four assemblages. At the bottom lies a Triassic metamorphic basement belonging to the Karakaya complex. Above it, separated by an unconformity, come clastic rocks, volcanic rocks and carbonates formed between the Liassic and the Early Cretaceous. The third assemblage consists of Upper Cretaceous blocky limestones, ophiolitic rocks and volcanic rocks, and the fourth of Eocene sedimentary and volcanic rocks. All of these units are overlain unconformably by younger sediments deposited in the Neogene basins of Suluova and Amasya. The sequence that MTA identified around Terziköy is a local section of this arrangement: the oldest unit is a Paleozoic metamorphic schist, above it lie Upper Jurassic-Lower Cretaceous limestones, and higher up come Cenozoic units.

In this zone the fault systems draw a geometry shaped like a half fishbone or a horse's tail. In the north lies the main strand of the North Anatolian Fault, in the south the Ezinepazar-Sungurlu Fault System, and in the middle the Esençay Fault and the Suluova Fault System. In general, east-west trending right-lateral main faults are complemented by north-east to south-west trending left-lateral linking faults. The depressions that remain between the faults have formed the Neogene basins. The Suluova Basin, made up of the Suluova, Merzifon, Gümüşhacıköy and Alıcık plains, developed under the control of the Suluova Fault System. The Amasya Basin, made up of the Aydıncık, Geldingen and Mecitözü plains, lies on the Ezinepazar-Sungurlu Fault System. The Geldingen Plain is the place where five important streams feeding the Yeşilırmak basin come together.

The age and formation of the basins are also treated in detail in the same thesis. The Suluova Basin began to open in the Middle Pliocene as a half graben under the control of the Bayırlı Fault Zone in the north-east, and developed as a depression closed to external drainage. From the Late Pleistocene, with the formation of the Eraslan Fault Zone in the south, the basin widened considerably and turned into a large lake, Lake Suluova. After the Middle Pleistocene the activity of the boundary faults ceased, and the east-west trending right-lateral Suluova Fault formed in the middle of the basin. In the Amasya Basin, the first deposition is represented by the Geldingen formation, which accumulated between the end of the Late Miocene and the Early Pliocene in a braided and meandering river environment. Two river terraces about 40 metres thick on the southern and south-western slopes of the Geldingen Plain have been dated by the OSL method and traced back to the Late Pleistocene, about 120,000 years ago. These ages show that in the recent geological past, too, the region continually changed shape under tectonic movements and climatic changes.

The recent seismic activity of the region is a product of the same system. In 1942 the Niksar-Erbaa earthquake on the North Anatolian Fault (moment magnitude 7.0) caused the death of about three thousand people. In this structurally active belt, the network of fractures and cracks offers convenient pathways for rainwater to percolate downwards, to be heated and to rise again, and this arrangement underlies the association of the region's hot water outlets with fault systems.

How the Water Reaches the Surface

In a fault-controlled hot water system, water descends along fracture zones, takes up the heat of the rock and returns to the surface along the fractures again. In Amasya the best documented example of this mechanism is the Terziköy field, where the MTA T-2 borehole advanced 325 metres. From the surface it first cut 10 metres of slope debris, then a sequence 253 metres thick of Eocene agglomerate, andesite, basalt, tuffite and flysch, and finally 62 metres of Upper Jurassic-Lower Cretaceous limestone. This limestone is the unit that works as the reservoir rock. The borehole produced water artesian, at a flow of 32 litres per second and a temperature of 40.1 degrees, and the wellhead pressure was measured at 1 atmosphere.

A notable finding of the report is that the clays and marls of the Eocene flysch have the character of a cap rock. The T-1 borehole drilled earlier in the field had not cut this clay and marl level; in T-2 it was cut over about 64 metres, and MTA considers this to have been effective in the higher temperature of T-2 compared with T-1. Indeed, the natural spring in the field is at 37 degrees, T-1 at 36.5 and T-2 at 40.1, while the small springs around it fall to 31 to 32 degrees.

The sample taken from T-2 was analysed in the central laboratories of MTA and fell into the "mineral-poor thermal water" group in the classification of the International Association of Hydrogeologists. The total mineralization of about 0.7 grams per litre measured in the Terziköy spring is also consistent with this classification.

Terziköy

Sources are inconsistent about which village the Terziköy spa belongs to. Some compilations place it in the district of Göynücek and others link it to Gözlek. MTA studies and encyclopaedic accounts, on the other hand, give the territory of Çivi village in the central district. The fact that there is also a settlement called Terziköy among the villages of Göynücek partly explains this confusion. One compilation gives its distance from the provincial centre of Amasya as 36 kilometres.

The geology and hydrogeology survey that MTA prepared under its contract with the Amasya Governorship covers an area of about 144 square kilometres around Terziköy and was published in February 1999. The report, which bears the names of Erdoğan Ölmez and Sinan Sarp, states that the emergence of the hot waters at the surface is controlled by fault systems trending north-east to south-west. At that time the hot water needs of the facility were met by the spa spring at 37 degrees and 10 litres per second and by the Terziköy-1 borehole at 36.5 degrees and 4 litres per second. Besides these, there are other springs in the area with a total flow of 6 litres per second at temperatures of 31 to 32 degrees. Combining soil gas measurements with geological data, the survey proposed a new fault-controlled borehole location at a depth of about 450 metres (plus or minus 50). Two years later, the report on the T-2 borehole, completed in 2001, states that the well was drilled to raise the temperature because the existing water sources were insufficient, and that the water was planned to be used in the facilities under consideration, for example in an Olympic swimming pool.

In terms of chemical composition, Terziköy water is bicarbonate, calcium and sodium type. Compilations give the milliequivalent percentages as 80.03 per cent for bicarbonate, 50.64 per cent for calcium and 28.01 per cent for sodium, and add that the water contains some carbon dioxide. The pH is 6.67, the total mineralization 0.7 grams per litre and the radioactivity 4.5 mache units. The same compilations describe the water as hypotonic and isothermal. Because of its content and temperature, the water is reported to be usable without cooling and, for the same reason, suitable for drinking cures.

There is no certain information about the history of the spa. In the foundation excavation of the hotel built right beside it, Roman-period water pipes and copper coins dated to the fourth century A.D. were found. On the basis of these finds, a wide-ranging Roman settlement in the surroundings is spoken of. At the head of the main spring, a wooden building with a pool of four metres by four metres and simple changing rooms, left over from the Ottoman period, is said to have stood, and the old pool is said to have been later enlarged and rebuilt.

Gözlek

Gözlek is a small village 23 kilometres from the provincial centre of Amasya, at about the twenty-second kilometre of the Göynücek road, at an altitude of 508 metres above sea level. Its population was 177 in 2022; from 606 in 1985, it has fallen markedly over the decades. The nearby Oluz Höyük gives a clue to the settlement history of the surroundings. In the records of 1926 the name of the village appears as Gözlek or Güzlek. The spa lies in a marshy area on the bank of the Çekerek River, and the water is said to contain abundant sulphur. In some accounts it is called Gözlek Bath or Gözhöyük Spa, and in the local language Gözlek Çermiği.

In the MTA inventory the natural outlet at Gözlek has a temperature of 39 degrees and a flow of 2 litres per second. This is the lowest-flow natural outlet of the three fields; together with the boreholes, the flow rises to 11.5 litres per second and the temperature range to 35.5 to 40.5 degrees. A temperature of 39.5 degrees is given for the pool water of the Gözlek Thermal Facility. According to information obtained from the provincial administration, a report prepared by the Department of Physical Medicine and Rehabilitation of the Ankara University İbn-i Sina Hospital counts the waters of Terziköy, Gözlek, Ilısu and Hamamözü in the group of oligo-mineral waters.

Exploration work around Gözlek is continuing. For a geothermal exploration and drilling project started by Vatan Organik Gübre Tarım Sanayi ve Ticaret A.Ş. to be carried out in Oluz village, the Ministry of Environment, Urbanisation and Climate Change decided that an environmental impact assessment was not required. According to the project file, the work covers an area of 10,776 hectares. The research of the MTA Geophysical Surveys Department has shown a hot water source of 38 degrees near Gözlek village, and this source is thought to be connected with the Ezinepazar Fault. The borehole is planned to reach a depth of about one thousand metres (plus or minus one hundred metres); the total investment cost is 9.35 million liras, and the project has been licensed by the Amasya Special Provincial Administration. Since no published data on the results of the planned drilling exist, it is not yet known whether the flow and temperature values of the field will change.

Hamamözü

Hamamözü lies about 90 kilometres from the provincial centre of Amasya, 40 to 43 kilometres from Çorum and 21 kilometres from Gümüşhacıköy. The district spreads over an area of about 204 square kilometres and is surrounded by Gümüşhacıköy and by Laçin, Osmancık and Mecitözü, which belong to Çorum province. The average altitude of the district is given as between 687 and 690 metres, while the area of the Arkut Bey Spa lies at 640 metres above sea level. In the district, which lies in a transitional belt between the climate of the Black Sea and that of Central Anatolia, winter is cold and snowy and summer hot and dry; the high ground is covered with forest and scrub, and the valley floors with farmland. The name of the district comes from the spa bath and from the word öz, meaning the stream that runs through it; according to the account, a bath was built over the spring and the settlement grew around it. This explanation is local tradition and is not supported by documents.

There are three springs at Hamamözü. In the tourism literature the water is written to belong to the group of sodium and bicarbonate waters, with a temperature of 38 degrees, a pH of 7.4 and a radioactivity of 6 mache units. Water samples taken from the Arkut Bey Spa on 20 July 1989 by the chemical engineer Ender Başak were analysed in the hydrology research laboratory of the Department of Medical Ecology and Hydroclimatology, and the mineral water was found to be of sodium bicarbonate, calcium, hyperthermal, oligometallic and hypotonic character. Another compilation writes that the water belongs to the group of sodium bicarbonate and calcium chloride waters and that the average temperature of the three springs is 38 to 40 degrees. The same compilation also states that the total mineralization of the Terziköy and Hamamözü waters is around half a gram, and that the two springs are regarded as close to each other in chemical structure and medical assessment.

There is a noteworthy difference between the temperature values. Some of the tourism publications give 38 degrees, and the MTA inventory gives 40 degrees for the natural outlet; 42.5 degrees is both the borehole value in the inventory and the spa temperature in the cultural tourism publications. It may be thought that this difference depends on the outlets at which, and the times at which, the measurements were made. In the inventory the natural outlet is written with a flow of 2.8 litres per second and the borehole with 125 litres per second. The large difference in flow between the natural outlet and the borehole points to the borehole having reached a wider fracture system beyond the small outlets seeping to the surface; however, no detailed geological survey explaining to which fault segment the Hamamözü springs are linked was found in the sources examined. The district centre lies at about the 35th meridian, that is, on the western edge of the Amasya Shear Zone as examined.

The history of use of the spa is long. Although the history of the Hamamözü Spa is not known exactly, it is estimated to have been in use since antiquity; it is reported that excavations have found evidence that it has been operated since the middle of the first century A.D. The water, which came out of the ground as a seepage, was turned into a bath with two domes, separate for women and men, in the Seljuk period at the time of Arkut Bey, and it continued to be operated in the Ottoman period as well. The history of the facility in the time of Arkut Bey is the subject of a separate article. After the Ottoman-Russian War of 1877-1878, migrants arriving from the Caucasus settled here and took over the management of the spa. The foundation of the present settlement of Hamamözü is dated to 1887: 60 households of Circassian migrants bought the farm of two notables from the nearby village of Gümüş. The settlement remained for a long time a township attached to Gümüşhacıköy, becoming a municipality on 20 August 1971 and a district on 20 May 1990.

Other Springs

Beyond the main fields, smaller hot water and drinking springs are known in various parts of the province. About 25 kilometres south of Amasya, between the villages of Misak and Çivi, lies the Hamam Spa, whose water is said to have characteristics similar to Gözlek. The Çırçır Spring Water at a place called Karakaya is known as a tasty and easily drunk drinking water. The Ilısu Spa within the borders of Göynücek is said to resemble Terziköy in its medical and technical features, but to have remained in the background because local administrations have not invested in it, serving only the local population. In the Hamamözü district, the Armut Spa on the Gümüşhacıköy-Hamamözü road is known as a spa that is good for rheumatism and skin diseases. The flow and temperature values of these small springs are not given separately in the MTA inventory; only around Terziköy are springs with a total flow of 6 litres per second and a temperature of 31 to 32 degrees written in the survey report.

Uses and Limits of the Water

The spa waters of Amasya are traditionally used for rheumatic complaints, nervous system diseases, stomach and intestinal complaints, skin diseases and women's diseases. Most of these benefits are passed on as compiled and traditional knowledge; it is stated that in scientific assessment the waters are counted in the oligo-mineral group and that cure applications are complementary and supportive in nature. It is also stated that the Terziköy and Hamamözü waters are similar in chemical structure and can be used without cooling because of their temperatures of 37 to 38 degrees.

From the energy point of view, these temperatures and flows are suitable for greenhouse heating and for heating pools and dwellings. The MTA inventory states that all three fields can be used for greenhouse heating. The difference between the thermal power values in the inventory is large: 3.84 megawatts are calculated for the Hamamözü borehole, while 0.26 megawatts are written for the Gözlek boreholes. Boreholes are drilled to supplement the natural outlets; T-2 at Terziköy was drilled to raise the temperature and the flow where the existing spring and the T-1 borehole were not sufficient.

Chronology

1877-1878: After the Ottoman-Russian War, migrants arriving from the Caucasus settle around the Hamamözü spa.

1887: Sixty households of Circassian migrants buy the farm of two notables from the village of Gümüş, and the present settlement of Hamamözü is founded.

1942: The Niksar-Erbaa earthquake of magnitude 7.0 occurs on the North Anatolian Fault.

20 August 1971: Hamamözü acquires municipality status.

20 July 1989: Water samples taken from the Arkut Bey Spa are analysed in the laboratory.

20 May 1990: Hamamözü becomes a district.

February 1999: MTA publishes its geology and hydrogeology survey of the Terziköy Spa.

2001: The Terziköy T-2 geothermal borehole is completed at 325 metres; artesian water at 40.1 degrees and 32 litres per second is obtained.

2000s: Modern thermal facilities come into service at Hamamözü.

Recent years: A decision that no environmental impact assessment is required is given for a geothermal exploration borehole of about one thousand metres in Oluz village.

Sources

Academic studies

  • Erturaç, Mehmet Korhan. Amasya ve Çevresinin Morfotektonik Evrimi. Doctoral thesis, Istanbul Technical University, Eurasia Institute of Earth Sciences (supervisor: Okan Tüysüz).

Official sources

  • Republic of Türkiye Ministry of Culture and Tourism. Hamamözü Arkutbey Kaplıcaları (Türkiye Kültür Portalı).

Other sources

  • General Directorate of Mineral Research and Exploration. Amasya İli Maden ve Enerji Kaynakları (geothermal inventory table and summary of the provincial geology).
  • Ölmez, Erdoğan; Sarp, Sinan (1999). Amasya-Terziköy Kaplıcası Jeoloji-Hidrojeoloji Etüdü. MTA Report No. 10251.
  • Özgür, Resul; Özkan, Hakan (2001). Amasya Terziköy 2 Jeotermal Sondaj Kuyu Bitirme Raporu. MTA Report No. 10448.
  • Güncan, Özlem (2020). Hamamözü Kaplıcaları. Online Türkiye Turizm Ansiklopedisi. turkiyeturizmansiklopedisi.com
  • Termal Rehber. Amasya İlindeki Şifalı Sular ve Kaplıcalar; Hamamözü (Arkut Bey) Kaplıcası. termalrehber.com
  • Kuzey Anadolu Fay Hattı article (Wikipedia); Gözlek, Hamamözü and Terziköy Kaplıcaları articles (Wikipedia).
  • ThinkGeoEnergy. Geothermal resource exploration and drilling operations start in Amasya, Türkiye.
  • Termal Kaplıcalar. Gözlek Kaplıcaları.

Online sources