1. The observations of the volcano were in charge of the National Meteorological Service of Portugal, the elements being collected by the Meteorological Observatory of Horta and plotted at Observatory Afonso Chaves, Ponta Delgada.
2. «Boletim Geomagnético preliminar», Observatório de S. Miguel (Açores), Serviço Meteoroloógico Nacional, Portugal, Director Prof. H. Amorim Ferreira, 1957 and 1958.
3. Melchior, P. J. —Les divers aspects des marées terrestre — Extrait du Bulletin de la Société Belge de Geologie, Bruxelles, Tome LXIV, fascicule 2, année 1955.
4. These ocean-tide data were computed at Meteorological observatory of Horta, National Meteorological Service of Portugal.
5. Dados astronómicos para os almanaques, Observatório Astronómico de Lisboa (Tapada), 1957, 1958 and 1947.