(Monte Albano or Colli Albani)
41.73 N, 12.70 E
summit elevation 949 m
Alban Hills volcano
forms a prominent feature on the southern skyline of Rome.
The volcano is seismically active, with several notable earthquake swarms since the early 1980's. Currently the western sector of the volcano is experiencing seismic swarms and a local uplift over a 6 km radius around the Albano maar.
Alban Hills volcano is part of the Roman volcanic potassic province that extends on the Tyrrhenian back-arc zone from southern Tuscany to Campania.
The most important structure of the volcano is the 8×8 km wide central caldera. The caldera is a horseshoe-shaped volcano-tectonic structure, related to eruptions from 561,000 to 355,000 years ago. The most recent eruptions occurred at Albano maar (Lago Albano).
Volcanic activity began 700,000 years ago with the emission of more than 150 cubic km of of mostly pyroclastic flows from a central cone. The caldera formed by repeated magma chamber collapses at the end of this phase 400,000 years ago. Eruptions which began inside the caldera built a second central cone erupting
both lavas and pyroclastic flows. The most recent eruptions consisted of phreato-magmatic explosions from several eccentric cones in the western side of the volcano that created craters, which are occupied by Albano Lake, and Nemi Lake.
Understanding whether the Alban Hills is an extinct volcano or is undergoing renewed activity is important for the city of Rome. Recent discoveries of Holocene phreatomagmatic and lahar deposits indicate that the volcano is still active, although currently quiet.
One of the oldest seismological observatories in the world, was built in 1894 on the northern flank of the central cone near the town of Rocca di Papa.
1989-90 Seismic Swarm
There were 3000 earthquakes detected between April 1989 and March 1990. The earthquakes centered on a 6 x 12 km area with a NW-SE trend, 20 km southeast of Rome. This area corresponds to the location of the most recent phreato-magmatic eruptions. The eastern side of the caldera rim and the central cone area lack earthquakes.
The earthquakes were located in two clusters. The first cluster was located
north of Albano Lake near the village of Marino. There earthquakes has focus depths from 3 to 5 km. The second cluster was located between the lakes of Nemi and Albano, with focus depths ranging from 4 to 6 km. There are several thermal
springs in the western Alban Hills and this suggests that the circulation of (water in the upper crust plays an important role in the active earthquakes in the area.
There was 30 cm of uplift measured at the Alban Hills during this period.