Periadriatic Seam
Encyclopedia
The Periadriatic Seam is a distinct geologic fault
in Southern Europe, running S-shaped about 1000 km from the Tyrrhenian Sea
through the whole Southern Alps
as far as Hungary
. It forms the division between the Adriatic plate
and the European plate
. The term Insubric line is sometimes used to address the whole Periadriatic Seam, but it is more commonly used to mean just a western part of it.
, the line marks the border between the Central Eastern Alps
and the Southern Limestone Alps
. In the Western Alps it forms the division between the southern Apulian foreland
and the central crystalline
zones of the Alps.
Continental collision
is still going on, with the Apulian and European plates still converging
. Movement along the Periadriatic Seam is the cause for the earthquake
zone between Vienna
and Friuli
. Meanwhile, the central zones of the Alps are rising too, causing vertical slip along the fault. The result is the set of major faultzones collectively named Periadriatic Seam. The uplift caused violent erosion
of the young orogen, which led to the formation of the Hohe Tauern
window
. At several regions a heavy uplift
of the Central Alps by some kilometers took place, and also a shift of more than 50 km.
Geologic fault
In geology, a fault is a planar fracture or discontinuity in a volume of rock, across which there has been significant displacement along the fractures as a result of earth movement. Large faults within the Earth's crust result from the action of tectonic forces...
in Southern Europe, running S-shaped about 1000 km from the Tyrrhenian Sea
Tyrrhenian Sea
The Tyrrhenian Sea is part of the Mediterranean Sea off the western coast of Italy.-Geography:The sea is bounded by Corsica and Sardinia , Tuscany, Lazio, Campania, Basilicata and Calabria and Sicily ....
through the whole Southern Alps
Southern Alps (geology)
The Southern Alps are a geological subdivision of the European Alps. The Southern Alps are the part of the Alps that are found south of the Periadriatic Seam, a major geological faultzone across the Alps...
as far as Hungary
Hungary
Hungary , officially the Republic of Hungary , is a landlocked country in Central Europe. It is situated in the Carpathian Basin and is bordered by Slovakia to the north, Ukraine and Romania to the east, Serbia and Croatia to the south, Slovenia to the southwest and Austria to the west. The...
. It forms the division between the Adriatic plate
Apulian Plate
The Adriatic or Apulian Plate is a small tectonic plate carrying primarily continental crust that broke away from the African plate along a large transform fault in the Cretaceous period. The name Adriatic Plate is usually used when referring to the northern part of the plate...
and the European plate
Eurasian Plate
The Eurasian Plate is a tectonic plate which includes most of the continent of Eurasia , with the notable exceptions of the Indian subcontinent, the Arabian subcontinent, and the area east of the Chersky Range in East Siberia...
. The term Insubric line is sometimes used to address the whole Periadriatic Seam, but it is more commonly used to mean just a western part of it.
Tectonics and geology
Within the Eastern AlpsEastern Alps
Eastern Alps is the name given to the eastern half of the Alps, usually defined as the area east of the Splügen Pass in eastern Switzerland. North of the Splügen Pass, the Posterior Rhine forms the border, and south of the pass, the Liro river and Lake Como form the boundary line.-Geography:The...
, the line marks the border between the Central Eastern Alps
Central Eastern Alps
The Central Eastern Alps comprise the main chain of the Eastern Alps with its highest peaks, located between the Northern Limestone Alps and the Southern Limestone Alps, from which they differ in geological composition....
and the Southern Limestone Alps
Southern Limestone Alps
The Southern Limestone Alps are the ranges of the Eastern Alps south of the Central Eastern Alps mainly located in northern Italy and the adjacent lands of Austria and Slovenia. The distinction from the Central Alps, where the higher peaks are located, is based on differences in geological...
. In the Western Alps it forms the division between the southern Apulian foreland
Foreland
Foreland is the easternmost point of the Isle of Wight. It is located three miles east of the town of Brading, and due south of the city of Portsmouth on the British mainland. It is characterised by a pub called the Crab and Lobster and various beach huts plus a beach cafe and a coast guard...
and the central crystalline
Basement (geology)
In geology, the terms basement and crystalline basement are used to define the rocks below a sedimentary platform or cover, or more generally any rock below sedimentary rocks or sedimentary basins that are metamorphic or igneous in origin...
zones of the Alps.
Continental collision
Continental collision
Continental collision is a phenomenon of the plate tectonics of Earth that occurs at convergent boundaries. Continental collision is a variation on the fundamental process of subduction, whereby the subduction zone is destroyed, mountains produced, and two continents sutured together...
is still going on, with the Apulian and European plates still converging
Convergent boundary
In plate tectonics, a convergent boundary, also known as a destructive plate boundary , is an actively deforming region where two tectonic plates or fragments of lithosphere move toward one another and collide...
. Movement along the Periadriatic Seam is the cause for the earthquake
Earthquake
An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time...
zone between Vienna
Vienna
Vienna is the capital and largest city of the Republic of Austria and one of the nine states of Austria. Vienna is Austria's primary city, with a population of about 1.723 million , and is by far the largest city in Austria, as well as its cultural, economic, and political centre...
and Friuli
Friuli
Friuli is an area of northeastern Italy with its own particular cultural and historical identity. It comprises the major part of the autonomous region Friuli-Venezia Giulia, i.e. the province of Udine, Pordenone, Gorizia, excluding Trieste...
. Meanwhile, the central zones of the Alps are rising too, causing vertical slip along the fault. The result is the set of major faultzones collectively named Periadriatic Seam. The uplift caused violent erosion
Erosion
Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...
of the young orogen, which led to the formation of the Hohe Tauern
Hohe Tauern window
The Hohe Tauern window is a geological structure in the Austrian Central Eastern Alps. It is a window in the Austroalpine nappes where high-grade metamorphic rocks of the underlying Penninic nappes crop out...
window
Window (geology)
thumb|right|350px|Schematic overview of a thrust system. The [[fault |hanging wall block]] is called a [[nappe]]. If an [[erosion]]al hole is created in the nappe that is called a window. A [[klippe]] is a solitary outcrop of the nappe in the middle of autochthonous material.A tectonic window...
. At several regions a heavy uplift
Tectonic uplift
Tectonic uplift is a geological process most often caused by plate tectonics which increases elevation. The opposite of uplift is subsidence, which results in a decrease in elevation. Uplift may be orogenic or isostatic.-Orogenic uplift:...
of the Central Alps by some kilometers took place, and also a shift of more than 50 km.
Geographic position and names
From east to west, the course of the Periadriatic Seam and the names given to it regionally are as follows:- Drau line: Southwestern Hungary - Styria - Drau valley (Jauntal, Rosental) - KlagenfurtKlagenfurt-Name:Carinthia's eminent linguists Primus Lessiak and Eberhard Kranzmayer assumed that the city's name, which literally translates as "ford of lament" or "ford of complaints", had something to do with the superstitious thought that fateful fairies or demons tend to live around treacherous waters...
) - Gailtal line: Gailtal
- Pustertal line: PustertalPustertalThe Puster Valley is a valley in the Alps that runs in an east-west direction between Lienz in Tyrol, Austria and Mühlbach near Brixen in South Tyrol, Italy...
- BruneckBruneckBruneck is the largest town in the Puster Valley in the Italian province of South Tyrol. Bruneck lies at the confluence of the Ahr with the Rienz Bruneck is the largest town in the Puster Valley in the Italian province of South Tyrol. Bruneck lies at the confluence of the Ahr with the Rienz...
- Meran - Giudicárie lineGiudicárie lineThe Giudicárie line is a major geologic faultzone in the Italian Alps, named for the Giudicarie valleys area. It runs from Meran in the northeast as a more or less straight line along the lower part of the Val di Sole, along the Val Rendena and then along the Chiese valley to the Lago d'Idro .The...
: Meran - Val di SoleVal di SoleThe Sole Valley is a valley in Trentino, northern Italy.Sole Valley applies to the Vermiglio Valley, the east-west aligned valley of the river Noce and its sidevalleys, among which the Peio Valley that heads to the Ortler... - Tonale or Insubric line: Tonale PassTonale PassTonale Pass is a high mountain pass in northern Italy across the Rhaetian Alps, between Lombardy and Trentino.It connects Valcamonica and Val di Sole...
- Val CamonicaVal CamonicaVal Camonica is one of the largest valleys of the central Alps, in eastern Lombardy, about 90 km long. It starts from the Tonale Pass, at 1883 metres above sea level and ends at Corna Trentapassi, in the comune of Pisogne, near Lake Iseo...
- ValtellinaValtellinaValtellina or the Valtelline valley ; is a valley in the Lombardy region of northern Italy, bordering Switzerland. Today it is known for its skiing, its hot spring spas, its cheeses and its wines...
- BiellaBiellaBiella is a town and comune in the northern Italian region of Piemonte, the capital of the province of the same name, with some 45,800 inhabitants as of 2009. It is located about 80 km northeast of Turin and about 80 km west-northwest of Milan.It lies in the foothills of the Alps,...
- Gulf of GenoaGulf of GenoaThe Gulf of Genoa is the northernmost part of the Ligurian Sea. The width of the gulf is about 125 km, from the city of Imperia in the west to La Spezia in the east. The largest city on the its coast is Genoa, which has an important port....
.