The volcano as an architectural host

More than 40 extinct volcanoes make up the Garrotxa Volcanic Zone Natural Park, in the pre-Pyrenean strip, one hundred kilometres north of the city of Barcelona. Espai Cràter, Museum of Volcanoes in Olot (capital of the Garrotxa region), is a new interpretation centre for this natural legacy that today forms an orography of gentle, habitable hills. It has been designed by VOL studio, an architectural firm founded by Toni Casamor and Anna Codina, in collaboration with BCQ. 

The architectural structure that makes up this interactive museum has been installed in the geological structure of a volcano, where magma once rose from the depths of the earth, to explain the intense activity in the bowels of the planet. The project proposed by the team of architects, by locating the building underground, also manages to free up a large extension of land for a new park. 

"The building forms part of the experience of visitors who understand the volcano as their host," VOL studio explains. On arrival, from the outside, only two entrances are visible, set into a hill. Facing each other, they generate an urban passage that crosses the interior of the building. "A contemporary museum cannot be just a neutral container capable of housing the museographic material. To build a museum is also to build the experience of its visitors. The building must influence people and be part of the message and values conveyed by the new centre. In contemporary museums, architecture and museography must blend and interact", reflects VOL studio.

All this translates into an architectural volumetry that recreates this millenary volcanic activity: the bulging shape of the exterior of the site is a reflection of the telluric force that modelled the mounds of the volcanoes. Some of the walls and skylights are tilted, illustrating the sudden movements of tectonics. The interior geometry on the visitor's tour is broken, affected by the seismic movement. 

"On the one hand, they help to raise awareness of the tectonic force of the subsoil, as if a seismic movement had disordered and destabilised walls initially built with clean, neutral geometries", the authors point out. Inside the main hall, the visitor has the privilege of seeing one of the original slopes of the volcano the excavation left visible, formed by cooled volcanic lava.  It is the real place of its entrails, nowadays sheltered by the architectural project that contains and explains it. 

The resources used to construct the building are based on the materials of the volcanic landscape of La Garrotxa. The concrete was formed with basalt stone. Clay and basalt stone were used for the interior paving, and the same stone was mixed with concrete for the exteriors. 

The use of ‘greda’, the name given to the cooled volcanic lava, was exceptional in this project. It is currently protected and cannot be extracted from its natural sites. But because the building was located on an extinct volcano and there was an abundance of it, while remaining in place, it was given new uses as an insulating and draining material behind the retaining walls. And as a material to lighten the weight of the roof, and even to add texture to some of the interior floors. 

Beech was chosen for the wooden surfaces and joinery, as it is a very representative wood species in the region. In fact, it is the tree that grows on the mound on the roof of the building, creating a new park for the city. Interwoven in this beech grove are a set of tree-inspired lampposts, designed by the architects themselves. "They are arborescent lampposts that simulate the flight of fireflies," the architects explain.

At night, the interior lighting of the building underlines its status as a volcano museum and highlights the red crack that runs through it. The skylights that provide zenithal illumination of the interior by day become screens of light among the trees at night. Espai Cràter is also the starting point for climbing an emblematic volcano of the region, Montsacopa, and the beginning of other excursions to volcanoes in the area.