(Neumann van Padang, 1993), a complex mountainous Iyang (Argopuro) in general here volcanic rock formed by volcanic tectonic structures, the Upper Pleistocene age, and occurs in basalt rock?. Is an active volcanic activities which continued until the age of Holocene, which form a cone-cone young. Fault blocks on the structure of the complex volcanic mountains Argopuro generally leads towards Southeast Northwest. Younger mountain complex formed from the complex mountainous Iyang (Argopuro). Lamongan mountain itself is a highly active volcanic activity at all, while the surrounding formed parasitic lava forming "Epigones".Regionally Lamongan mountain complex is the central axis of the island of Java that make up the structure of the anticline, also influenced by tectonic depressions. Eruption slit open leads West - east along the 4 km between Klakah to the top of Lamongan, it is influenced by local earthquakes (earthquakes volcanic). (Van Bemmelen, 1938) suggests the formation of mountains of south eastern part of the evolution that is occurring from Neogen until QUARTERLY as follows:1. Between the Lower Miocene - Middle Miocene, volcanic activity occurred largely towing.2. At the end of the middle Miocene, occurred pembubungan on Java geantiklin axis that forms the batholith that gave birth to rock grenit, known pr is "Merawan Batholith".3. After the denudation, geantiklin Java decreases no return, and the Upper Miocene age genang the sea in the south (transgressi), which is formed from limestone sedimentary rocks (limestone).4. In the Plio-Pleistocene age, geantiklin area becomes parallel to the sea level is mainly along the northern coast.5. In the Upper Pleistocene, volcanic activity occurs that forms the north shore mountains (Ringgit - Straight), larger volcanic activity and devastating namely igneous rocks that form the peak pacific geantiklin like (Tengger, Iyang / Argopuro), Ijen), even this is accompanied by appointment geantiklin Java.6. At the end of the Pleistocene, mostly like the old Tengger, Iyang / Argopuro, Ijen volcanic activity is leading toward a low geosiklin areas especially in the north, this is caused by the folding / folding structure.7. During the Holocene appears volcanic-young volcanic included in 'Zona Solo "like (Semeru, Lamongan, roar, Ijen in the form of a cone, and so on).During that emerged a new fault fault-like "slip fault" "eruption gap" "depression" and so on.Volcanic activity occurs in middle age appears Recent bleak northern coast section (Bahrun, Complex Straight, RoW) and so forth, and appeared on track "reverse fault".

The appearance of the geological structure in the area of mapping different kinds of them are found is as follows; shear fault, normal fault, the eruption side / slit and others. From the results of field data, fault structures formed prior to the latter is as follows;"Pekalen fault" which allegedly is an old fault in this area, where the direction of this fault extends nearly east-west direction and starts from village to village Kedaton Ranoagung. The type of fault which appears on the surface of the estimated fault eruption gap (fissure eruption). And after the formation of this fault allegedly appeared small lakes through the fault plane is weakest. Estimation even this can not guarantee the truth, whether with the emergence of these lakes through the cracks eruption or the influence of depression, a clear appearance are 2 alternatives. Lake crossed by fault lines are lake Rano Birds entirely without water (dry) of the region paleran Anjur - Tiris. The next cesarean is Kedaton fault; which is a fault trending shear nearing the north - south, with the appearance of this fault is suspected after the formation of the eruption of the unit Qva and QPA, mountain Gambir began its activity increased and delivery unit Qvg urgent volcanic rocks and the resulting side of this fault is formed

Lamongan fault; an eruption fault gap (fissure erupti on) are trending northwest - southeast, and allegedly happened after cesarean Kedaton appear. The appearance of the eruption gap is likely to be influenced by local earthquakes (earthquakes volcanic), because complex Lamongan mountain is still classified as a complex of volcanoes that are still active. Followed ole fault Ranoagung (Ranoagung Tiris fault and fault, the alleged emergence of the same surface. Both these faults are parallel trending northwest to the southeast. On Ranoagung fault the type of fault from the eruption of a gap that extends along the lakes that appear on the surface, such as a lake Twins I, II twin lakes, lake Ranoagung, Red Rano lake, and the lake Segaran Duwas. (See the map geological map in appendix no. I). leak fault is a fault shear occur simultaneously with the great Rano fault. The appearance of this alleged source of hot water emerge and rise to the surface is via Tirisi fault. The hot springs fault lines through which there is a location near the hot sub-group is thought to emerge and rise to the surface is via Tiris fault. The hot springs were passed fault lines have 2 locations ie adjacent subgroups Tiris hot water and Segaran.Segaran fault; which is thought to be the fault of the youngest and form a normal fault trending southwest - northeast. The area of this Segaran two normal faults are formed so that the pattern of these structures tend to form a pattern structure "graben", this is the case most likely there is a small depression influence in this area and is characterized by the appearance of the lake as in Rano Segaran.