Monitoring the cooling of the 1959 Kīlauea Iki lava lake using surface magnetic measurements
Résumé
Lava lakes can be considered as proxies for small
magma chambers, offering a unique opportunity to investigate
magma evolution and solidification. Repeated magnetic
ground surveys over more than 50 years each show a large
vertical magnetic intensity anomaly associated with K
ī
lauea
Iki Crater, partly filled with a lava lake during the 1959 erup-
tion of K
ī
lauea Volcano (Island of Hawai
’
i). The magnetic
field values recorded across the K
ī
lauea Iki crater floor and
the cooling lava lake below result from three simple effects:
the static remnant magnetization of the rocks forming the
steep crater walls, the solidifying lava lake crust, and the
hot, but shrinking, paramagnetic non-magnetic lens
(>540 °C). We calculate 2D magnetic models to reconstruct
the temporal evolution of the geometry of this non-magnetic
body, its depth below the surface, and its thickness. Our results
are in good agreement with the theoretical increase in thick-
ness of the solidifying crust with time. Using the 2D magnetic
models and the theoretical curve for crustal growth over a lava
lake, we estimate that the former lava lake will be totally
cooled below the Curie temperature in about 20 years. This
study shows the potential of magnetic methods for detecting
and monitoring magmatic intrusions at various scales.