Morphology Of The Berca Mud Volcanoes

Mud volcanoes at Berca

The mud volcanoes are situated within the area of Berca village, Buzau county, on the left bank of the Berca river. They develop in the Berca depression in several places, known by such names as (from south to north): “La Fierbatori”, “Paclele Mari”, “Paclele Mici”, “Beciu”. Access road is the Buzau-Brasov highway; at a crossroads in Satuc (a small town situated 20 km far from Buzau, which can be also reached by railroad) , a modernized byroad leads afer 2 km to the village of Berca. From here, two carriageable roads end up in the mud volcano fields.

These volcanoes have been known for more than a century and have aroused the interest of researchers on account of their connection with the oil fields located on the same area and of their extremely original manifestation.

Types of mud volcanoes in the world and in Romania.Mud volcanoes are distinguished from “normal” volcanoes through their genesis, the released material of the eruption, and conspicuously reduced forms and phenomenas. They emerge as a result of natural gases (methane) eruption, post-volcanic emanations (solfatara and fumarole) and seismic impact.

Mud volcanoes which erupt due to natural gas eruption. They result from emanations of gas released from store-rocks situated at various depths. In its way to surface, the gas carries fresh or salt water, which softens and weathers the encountered rocks and soil layers, bringing them to surface along minimal resistance lines.

This type of mud volcanoes are to be found in Russia, Italy, North Iran and Iraq, India and Burma, in the south of the USA, Venezuela, Colombia, Romania. In Romania, they are located in the Transylvanian Depression (Cluj, Alba, Sibiu and Mures counties), the Moldavian Plateau(Iasi county), in Gorj Subcarpathians and in Buzau Subcarpathians .

The Berca depression covers the area between the locality of Berca to the south and the locality of Beciu to the north. It is carved in soft Pliocene rocks forming an alteration of marls and partly cemented sands. These rocks form the Berca-Abanasi anticline which in its axial area has two heights, where Meotian deposits in Berca and Beciu can be seen in outcrop.The anticline is cut by a range of transversal and longitudinal faults (with consequences in the mud volcanoes genesis).

The Berca depression in carved in the axis of the Berca-Arbanasi anticline and is a beautiful relief inversion and a typical anticline weald. The anticline fold has a length of about 18 km and develops on the NE-SW direction, the depression having the same orientation; the Beciu depression, to the NE of the fold, also a typical anticline weald is similarly orientated.The two ranges of heights forming the eastern and western sides of the depression follow the anticline limbs; the inner slopes are steeper and form two lines of main cuestas, opposite one another.

In the Berca depression occur a wide range of slope processes, having an intensive development, rarely to be found in other areas. Their genesis is mainly due to tectonic mobility and lithological structure of the region, to the deforestation and also to the torrential character of rainfalls(600-700 mm annually).

Specific to this area are the large valleys, known as derasion valleys in the form of long amphitheaters, with strong slopes to the watershed and gentle slopes of the longitudinal profile. The heights of these valleys may reach 500 m and it can be 1 km long. Their genesis shoud be sought in the periglacial phenomena, as a consequence of congelifluction processes, of massive soil shifting on the slopes and in fine material washing in the wet interglacial periods.

Landslides are also very common, either superficial or profound, as well as solifluctions and mud flows.The Berca depression is also the only place in our country where Nitraria schoberi, a specific plant which usually grows in Central Asian regions can be found. The flora is characteristic to the southern forest steppe with various pontic and submediterranean species.

Morphology of the Berca mud volcanoes. The Berca mud volcanoes are not very high; taking into account the external aspect of their eruptive apparatuses, they can be grouped into: mud volcanoes and boiling mud. The term “saratura”(salt-flat) is known as salting zones and volcanoes that