Thermal condition of Surtsey BY

• Main Authors: Gudni Axelsson, Valgardur Stefansson, Gudjon Gudmundsson
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Surtsey
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.595.5601; http://www.surtsey.is/SRS_publ/1982-IX/1982_IX_3_04.pdf

The results of temperature measurements per-formed in a borehole drilled on Surtsey in 1979 are presented. These results are used as the basis for a discussion of the thermal condition of Surts-ey. The hypothesis that intrusions rather than pillow lavas are responsible for the excess heat content of Surtsey is favored, but it is concluded that the 13 meter thick dike complex found in the drill core is not sufficient to explaill the thermal condition of the island. An average thickness of intrusions of at least 20 meters is needed. It is demonstrated that the heat transfer in Surtsey has been dominated; by llydrothermal convection and that the system is vapor dorni-nated above sea level. The permeability of the altered tuff in a 40 meter thick section below sea level is estimated to be 2.5x10-1%2. The permeability of the unaltered tuff above sea le-vel is estimated to be about 1.4~10-10 m2. The purpose of the drilling was to obtain a continous core (4.7 cm diameter) for the investi-gation of the structure of the island and the hydrothermal alteration of the tuff formed dur-ing the initial phase of the Surtsey eruption. The core has been described by Jakobsson & Moore (1982) and a simplified presentation of the lithology observed in the core is giver1 in Fig. 2. The drill hole makes it possible to study the thermal conditions within-the island. The res-ults of temperature logging performed by the Icelandic National Energy Authority (NEA) in