Hamburg's geological underground
Hamburg's geological subsurface was formed by different geological processes of northern German glaciation.
Landscape genesis
Magpie Ice Age
During the Elster Ice Age (400,000 to 320,000 years ago) meltwater erosion cut grooves up to 400 meters deep into the Hamburg underground, which were then filled with sand. Today they form the most important aquifers for Hamburg.
Saale Ice Age
During the Saale Ice Age (300,000 to 126,000 years ago) the Scandinavian inland ice sheet penetrated as far as Lower Saxony . The deposited marl boulder , which consisted mainly of sand, gravel and boulder clay, formed a gently undulating to even geest area on both sides of the Elbe valley at heights between 20 and 60 meters above sea level. Outstanding elevations in the Hamburg area are the Blankeneser ridge with the Baursberg of 80 meters and the Süllberg of 93 meters and the Harburg mountains up to 155 meters.
Extensive lowlands with sandy soils and high water levels created a large number of up to 8 meters thick raised bogs north of the Elbe , such as the Liether Moor, Himmelmoor , Holmmoor , Ohmoor , Glasmoor , Wittmoor and Eppendorfer Moor .
Vistula Ice Age
At the end of the last ice age ( Vistula ice age from 115,000 to 11,600 years ago) glaciers from Scandinavia penetrated to a line north of the Elbe. The Elbe glacial valley served as a drainage path for meltwater from the Vistula period along the end moraine of the glacier. Extensive valley systems, such as the Alster , Bille , Wandse and Pinnau, were cut into the Geest floors by the runoff of the meltwater . Together with the Elbe Valley, they still determine the geomorphological shape of Hamburg today.
The for North Sea flowing meltwater masses left behind large amounts of deposits mainly of clay , peat and sand . As a result, extensive layers of sand were created, which act as aquifers and are of great importance for Hamburg's drinking water supply today. The organic deposits initiated the formation of brown coal and oil deposits.
With the rise of the sea level at the end of the last ice age, the tide-dependent penetration of the North Sea water into the Elbe valley occurred . Shifts in the course of the river, the formation of banks and the splitting of the river gave rise to the marshland between the North and South Elbe Strominseln ( Werder ), which gave the districts of Finkenwerder , Altenwerder and Ochsenwerder their names.
The extensive Oberalstertal lowlands with the central Duvenstedter Brook arose from ice reservoir sediments and high groundwater levels .
The meltwater runoff below the glacier formed so-called tunnel valleys . In the east of Hamburg, the Meiendorfer-Stellmoor Tunneltal was built with a box-shaped cross-sectional profile and varying widths from 100 to 400 meters. They drain into the Wandse. The valley floor, filled with sediments and peat, still exists today. The excavations carried out by the German prehistorian Alfred Rust between 1935 and 1936 brought to light Neolithic finds by reindeer hunters, which indicate a summer camp of the hunters. The distribution area is drawn with Hamburg culture .
Salt domes
About 260 million years ago ( Upper Permian ), extensive salt domes emerged from the interplay between the filling of the North German Basin with seawater and the subsequent evaporation over a period of 10 million years . In the Hamburg region there are nine salt domes (salt diapirs) of different shapes and depths. The mightiest salt dome is the Othmarschen Langenfelde Diapir (OLD). It is located in the north-west of Hamburg and extends from the Elbe over about 20 km in a north-easterly direction to Quickborn . The salt dome is up to 3000 meters deep, in some areas it reaches a few meters below the surface.
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The thickness of the salt dome at Reitbrook follows with an extension of about 4 km and a depth of 800 meters. The location and structure of the salt domes in the Hamburg area are shown schematically in a geological 3D model (Geotectonic Atlas of Northwest Germany).
The Sottorf and Meckelfeld salt domes in Lower Saxony and the Geesthacht-Hohenhorn , Siek - Witzhave and Sülfeld salt domes in Schleswig-Holstein are located in the vicinity of the Hamburg metropolitan area .
When the salt dome comes into contact with groundwater or seepage water , leaching occurs, which can form large caverns in the salt dome.
Above the salt dome Othmarschen Langenfelde Diapir several were sinkholes on. The Bahrenfelder See (size: 5130 m², elevation: NN + 24 m) was created in this way through a near-surface salt cavern and a subsequent collapse ( sinkhole lake ).
The Flottbek Markt sinkhole has slightly inclined edge structures that indicate a slow decline.
The Wobbe Lake sinkhole , about 250 m northwest of Flottbek Markt, shows steep edge structures that suggest an abrupt slide of the soil structure. With the high-resolution shear wave seismic the structure of the Wobbe-See-Sinkhöhle at a depth of 60–80 m below the surface could be verified. In this area subsidence rates of 1 mm / year were determined.
In the past 200 years, more than 30 seismic tremors - triggered by sinkholes - occurred in the Hamburg area , mainly in Groß Flottbek and Bahrenfeld :
| Event date | place | Intensity / classification | event |
|---|---|---|---|
| 01/22/1760 | Groß Flottbek | - / C | |
| 08/08/1771 | Hamburg | IV / A | Five oaks disappeared in a sinkhole in Bahrenfeld. |
| 01/24/1834 | Hamburg | - / C | |
| 1896 | Groß Flottbek | - / C | |
| 11/07/1898 | Hamburg | - / C | |
| 1903 | Groß Flottbek | - / C | |
| December 07, 1904 | Hamburg | II-III / C | |
| January 16, 1907 | Hamburg | III / C | |
| 1912 | Groß Flottbek | - / C | |
| 1914-1918 | Groß Flottbek | - / C | |
| 1918-1921 | Groß Flottbek | - / C | |
| 10/06/1929 | Groß Flottbek, Wobbe See | weak / A | Weak tremor |
| December 09, 1930 | - / C | ||
| 04/10/1935 | - / C | ||
| 1936-1937 | - / C | ||
| 07/01/1938 | Groß Flottbek, Wobbe See | - / A | Weak damage, gaping cracks in the masonry damage, overturned furniture. |
| 1947 | - / C | ||
| 1955 | - / C | ||
| March 19, 1960 | Groß Flottbek | strong / A | Strong vibrations and shocks, long-lasting, strong vibrations, cracks in the apartment ceilings, extinguishing of the electric light. |
| 1961 | - / C | ||
| 01/30/1963 | Groß Flottbek | weak, 3-5 cm / s / A | Light tremors, deep rumbling, swaying and rocking houses. |
| 07/01/1983 | Weak tremors, overturned furniture, cracks in the masonry. | ||
| 04/08/2000 | Groß Flottbek | IV / A | Strong vibrations, explosive noises. |
| April 8, 2009 | Groß Flottbek | III / A | Strongly felt tremors, people leave their houses, after about 1 hour aftershocks. A cavern incursion below the epicenter at a depth of about 100 m is assumed. |
| 04/28/2009 | Groß Flottbek | weak / A | Weak tremors. |
(Classification of the source: A-trustworthy, C-unsafe )
Layers of sand as an aquifer
At the end of the last ice age, layers of sand were created by the deposits of the glacier reaching as far as Hamburg, ranging from 500 meters deep to a few meters below the surface. They formed six aquifers in Hamburg and gave Hamburg a self-sufficient groundwater supply without Hamburg having to rely on additional bank filtrate - as is the case with many other large cities.
During the first drilling for drinking water production , the water emerged from the aquifers under high pressure like a fountain. Today this phenomenon, which is known as artesian groundwater , no longer occurs, as the underground water pressure has decreased due to the permanent extraction of groundwater.
Today, the drinking water supply of Hamburg and the Hamburg area comes exclusively from the groundwater and is provided by 17 groundwater works with a total of 461 wells from depths between 20 and 429 meters.
Hamburg has approx. 630 groundwater measuring points of the authority for environment and energy as well as approx. 390 groundwater measuring points of the Hamburg waterworks . The extent and depths of the Hamburg aquifer are shown in a hydrogeological 3D structural model. It is used to assess the risk of near-surface groundwater in order to identify possible flow paths from the surface to the groundwater or when pollutants penetrate the soil.
Table: Hamburg geological formation and waterworks (based on E. Koch 1955, W. Drobek 1948 and 1955, supplemented by technical data on the groundwater body and the depth of the well from 2009 by the Environment and Energy Agency)
| Geological timescale | Facies | Subsurface floor (groundwater body) |
Waterworks from 1955 (well depth) |
|---|---|---|---|
| Holocene | Elbe water | 0 | Kalte Hofe, Baursberg |
| Klei | |||
| River sands | |||
| Young Pleistocene | Valley sand | 1 (G1-AB) | Curslack, Billbrook, Moorburg, Falkenstein, Süderelbmarsch, Haseldorfer Marsch (17 m) |
| Pleistocene | Boulder clay with sand and gravel deposits |
2 | Rissen, Großhansdorf, Schnelsen, Bilbrook, Neugraben, Falkenstein, Bilstedt, Borstelbek (76 m) |
| Sea clay, 1st interglacial |
|||
| Lauenburg clay | |||
| Old Pleistocene | Fine sands | 3 | |
Boulder clay with sand and gravel deposits |
4th | Billbrook, Stellingen | |
| Pliocene | Kaolin sands | 5 (G1-D) | Stellingen, Großhansdorf (177 m) |
| Upper Miocene | Mica tone | ||
| Middle Miocene | Upper brown coal sands | 6 (G2-E) | Industrial companies |
| Hamburger clay | |||
| Lower Miocene | Lower brown coal sands | 7 (G3-F) | Großensee, Curslack, Bergedorf, Wilhelmsburg, Neugraben, Lohbrügge, Borstelbek (300 m) |
| Sands and clay of the four-country level | |||
| Older layers |
Lignite deposits
Lignite was formed around five million years ago of the Tertiary from silted swamp forests and moors. When the glaciers of the Elster Ice Age pushed over northern Germany, the remains of plants and animals were repeatedly covered over the millennia by rubble and layers of sand. The increasing pressure on the organic deposits led to their carbonization .
In the entire Hamburg metropolitan area, three brown coal seams with layers of 8 to 10 meters, which are separated by layers of clay, extend at depths of 100 to 500 meters. Between 1919 and 1922, 50,000 tons of lignite were extracted in the Robertshall mine in the Harburg mountains and used to fire the Phonix Gummiwerke boiler . The material extracted consisted of an average of around 45% sand and 55% lignite. Today this lignite is considered unprofitable.
Natural gas and oil deposits
During drilling work to search for drinking water resources in the south-east of Hamburg, near Neuengamme , natural gas was discovered on November 4, 1910 at a depth of just 250 m. The gas, which escaped under a pressure of 27 bar, ignited at the borehole. The fire ( the cross of flames from Neuengamme ) could only be extinguished after 20 days, and the borehole was secured with a concrete slab. Gas production began after five years, which produced 231 million m³ of gas over 7 years. The natural gas discovery in the Neuengamme marshland also gave rise to further drilling for natural gas and oil.
In 1937, the "Reitbrook-Alt" oil deposit was discovered in the vicinity of the gas deposits above the apex of the Reitbrook salt dome at a depth of 665–800 meters. Between 1937 and 1942 almost 1 million tons of oil were produced. Annual production peaked in 1940 with 350,000 tons. In 1960 the "Reitbrook-West" oil deposit was developed. A total of 345 deep boreholes were drilled into the reservoirs at Reitbrook, the locations of which are shown on a map in (sectional drawing of the oil field above the Reitbrook salt dome in).
The oil production was 80,000 tons in 1965, the cumulative output was 2.2 million tons until it was stopped in 1973. The storage facility was then expanded into a natural gas storage facility , which was operated until 2014.
To resume oil production at Reitbrook-Alt, production tests were carried out again in 2017 to identify the most productive boreholes. Adjacent to the Reitbrook oil fields, two further oil deposits, "Meckelfeld-Alt" and "Meckelfeld-Süd", were developed in the Hamburg area - above the Meckelfeld salt dome. The production up to 1993 produced a total of more than 2 million tons of oil.
The landscape of the region is still characterized today by the distinctive structures of the deep pumps , the so-called "horse head pumps", which are used for oil extraction from great depths and low reservoir pressure .
The extraction of crude oil created cavities with a capacity of up to 380 million m³ (pore spaces in the underground rock layers), which today are used as natural gas storage (pore storage) with a volume of 350 million m³ and serve to supply Hamburg with natural gas.
Soft layers
The near-surface soils of the Elbe and Alster lowlands were formed by the glacial valleys and consist of soft layers such as clay, peat and sand. The Alster lowlands also extend over part of Hamburg's inner city from the Inner Alster , along the Hamburg canal to the Elbe. The course of the lowland is bounded on both sides by Geestrücke. The western Geestrücken lies in what is now the Neustadt district .
The eastern Geestrücke is formed by the Alster, Bille and Elbe into a tongue of the Geest, which at the time of Hamburg's first settlement was an ideal shelter on which the Hammaburg was also built. Today it is part of the Hamburg-Altstadt district , where the Domplatz and St. Petrikirche are located. The name of the street, "Bergstraße" from the Inner Alster to the St. Petrikirche, indicates the difference in altitude there between the Alster lowlands and the Geest.
Height differences in downtown Hamburg:
| Geestrücken-West | Alstern low | Geestrücken- East | ||
|---|---|---|---|---|
| Holstenwall 16 | Old Steinweg 1 | Jungfernstieg | Cathedral Square | Mönckebergstrasse 7 |
| 26 m | 10 m | 6 m | 12 m | 31 m |
The foundations of large structures in the swampy bottom of the Alster lowlands pose particular challenges.
The construction of the 112 meter high Hamburg town hall in the Alster valley had to be erected on 4000 oak piles and a 1.60 meter thick base plate until it was completed in 1897 after 10 years of construction.
Individual evidence
- ↑ Klaus Schipull: Hamburg: City and Harbor - Surrounding Area and Coast . 37 geographic excursions (Hamburg Geographical Studies), issue 48, Institute for Geography at the University of Hamburg, January 1, 1999.
- ↑ Klaus Schipull: The natural landscapes in the greater Hamburg area - brief explanation of an overview map (page 1–7 in "Hamburg: City and Harbor").
- ^ Jürgen Ehlers: The Quaternary in the Hamburg area (page 9-19 in "Hamburg: City and Harbor").
- ^ M. Haacks, B. Pflüger, D. Thannheiser: Dove Elbe and Bergedorf - Langschaftsgenese, vegetation and land use (page 225-238 in "Hamburg: Stadt und Hafen").
- ↑ Nature reserve - NSG Höltigbaum, NSG Stellmoorer Tunneltal , authority for environment and energy.
- ↑ Hiking map NSG Höltigbaum .
- ↑ a b c d e Ulrich Alexis Christiansen: Hamburg's dark worlds - The mysterious underground of the Hanseatic city , Christoph Links Verlag, 1st edition, April 2008 ( ISBN 978-3-86153-473-0 ).
- ↑ a b Volker Looks: The Alster - the river and the city, Wachholtz Verlag, 2012 ( ISBN 978-3-529-05153-1 ).
- ↑ Erdsenken in Hamburg , written small inquiry, printed matter 19/6773, July 23, 2010 (with illustration of the location of the salt structures in the Hamburg area, from Baldschuhn et al. 2001: Geotectonic Atlas of Northwest Germany and the German North Sea Sector ).
- ^ A b Friedrich Kausch: Geotechnical characterization of the Hamburg building site
- ↑ Extract from the geological model - salt domes in the area of the FHH
- ↑ Earthquakes, collapse quakes and depressions in Hamburg , Jura Magazin.
- ↑ Der Bahrenfelder See , Hamburg Authority for Urban Development and Environment.
- ^ A. Grube, F. Grube: Geomorphology of salt domes in Holstein - salt dome Bahrenfeld (page 489-501 in "Hamburg: City and Harbor").
- ↑ CharLotte Krawczyk, Ulrich Polom, Stefan Trabs, Torsten Dahm: High-resolution imaging of sinkhole structures in the city of Hamburg by urban shear-wave reflection seismics , Geophysical Research, Vol. 13, EGU2011-1302, 2011.
- ↑ Torsten Dahm, Sebastian Heimann: Seismological investigation of the microquakes in Flottbek Markt, Hamburg, from April 2009 and their possible causes , Institute for Geophysics, University of Hamburg, Wilhelm Bialowons, Deutsches Elektron-Synchrotron DESY, Hamburg, June 23, 2009.
- ↑ An integrative geodetic-gravimetric approach to the exploration of subrosion in the Hamburg-Flottbek sinkhole area - surface deformation and mass transfer , portal for geoinformation, geo-IT and geodesy.
- ^ Earthquake in Hamburg on April 8, 2000 , authority for urban development and the environment.
- ^ A b Torsten Dahm: A seismological study of shallow weak micro-earthquakes in the urban area of Hamburg city, Germany, and its possible relation to salt dissolution , Natural Hazards, September 2011, Volume 58, Issue 3, pages 1111-1113.
- ↑ Groundwater protection in Hamburg (Schematic representation of the aquifers) , Authority for Environment and Energy - Water Management.
- ↑ Drinking water production , Environment and Energy Agency.
- ↑ Water protection areas and locations of the waterworks , authority for the environment and energy.
- ↑ Groundwater level explanations on the groundwater level plans , Authority for Environment and Energy - Water Management, Jan. 2014.
- ↑ The deeper geological subsurface of Germany , submission for the commission "Storage of highly radioactive waste" Hanover, October 2014.
- ^ Hydrogeological model of the medium-deep subsoil , Authority for Urban Development and Environment, Hamburg.
- ↑ Hans-Jürgen Gäbler: Building Ground and Development of Hamburg - The Influence of the Natural Subsurface on the Development of a World Port City , Hamburg Geographic Studies, Volume 14, Institute for Geography and Economic Geography of the University of Hamburg, 1962.
- ↑ Groundwater protection in Hamburg , authority for the environment and energy.
- ↑ Our supply area and the responsible waterworks , authority for the environment and energy.
- ↑ Michael Grube: A brown coal mine near Hamburg - Robertshall .
- ↑ a b c 80 years of oil production in Hamburg .
- ↑ A bang 100 years ago triggered the industrial age in the Vierlanden - The Flame Cross of Neuengamme , Peter von Essen, Bergedorfer Bürgererverein, Sept. 2010.
- ^ Kick-off for petroleum from Hamburg , February 1, 2017.
- ↑ Oil production instead of natural gas storage - GDF-Suez buys Reitbrook storage facility from subsidiary Storengy .
- ^ A table for the cross of flames , De Latücht, No. 82, Dec. 2010.
- ↑ Reitbrook natural gas storage facility , Storengy storage facility Reitbrook.