Cumbre Vieja: Science after the tragedy

The CENIEH, the CSIC, and the Universidad de Burgos collaborate on studying the volcanic materials from the eruption of this volcano on the island of La Palma, in the Canaries, to improve our knowledge of the Earth's magnetic field

Apart from enhancing our comprehension of volcanism per se, the emblematic material it generated, the lava, offers a one-off opportunity for understanding how this records certain properties at the moment of formation, such as terrestrial paleomagnetism. Josep M. Parés, an expert in this field at the Centro Nacional de Investigación sobre la Evolución Humana (CENIEH), has returned to the zone of the Cumbre Vieja volcano (on La Palma, Spain), following fieldwork carried out 50 days after the eruption, to gather further data and take geological samples for subsequent study as part of a joint CENIEH-Universidad de Burgos-CSIC initiative.

Over a week, this mixed research team, whose other members are Manuel Calvo, Angel Carrancho, Eva Vernet (Universidad de Burgos), and Vicente Soler (IPNA-CSIC), extracted numerous samples of lava from different spots on the shoulder of the volcano, as well as collecting volcanic ash, and these materials will be analyzed over the next few months in Burgos, to enhance our knowledge of the Earth's magnetic field and the mechanism by which this becomes imprinted in volcanic rocks.

One of the foundations and premises of paleomagnetism is precisely that rocky materials acquire and retain the ambient terrestrial magnetism at the moment of their formation. However, we also know that that record, or paleomagnetic signal, can often be imperfect. In other words, the magnitude and orientation of the magnetic field, as determined in the rocks, could be less dependable than we thought.

To establish how reliable paleomagnetic measurements are, it would be necessary to characterize the signal in materials formed under a magnetic field that is known, in terms of time, direction, and magnitude. These conditions are now met to an exceptional extent in the volcanic materials generated by Cumbre Vieja.

“The zone around Cumbre Vieja is an ideal scenario for generating new rocks because, on the one hand, the conditions of the site are known and, on the other, it is possible to measure the magnetic field's magnitude and orientation, and in real time too”, explains Parés.