Abstract:
A programme to monitor volcanic activity about the active summit crater of Mt Erebus was conducted by the NZ Geological Survey from December 1980 to December 1985. The surveys were made annually in conjunction with the International Mount Erebus Seismic Studies project.
The main components of the survey were as follows: (1) Horizontal deformation of the summit area was monitored by a triangulation network of five stations on the rim of Main Crater connected to two stations on more stable ground on the outer rim. (Five further stations were added in 1984 to include Side Crater and the Nausea Knob area.) (2) Vertical deformation was monitored by four tilt levelling (i.e. dry tilt) patterns. (3) Horizontal and vertical deformation of Main Crater floor was monitored by an eight-marker alignment before it was destroyed by eruptions in 1984. (4) Short term horizontal deformation during declining eruptive activity in December1984 was monitored by repeat electronic distance measurements (EDM) of four lines on the outer slopes of Main Crater. (5) An alignment of seven stations near, and including, the original Erebus Hut, was surveyed annually to determine whether Camp Flow was a lava flow or a lava bomb-covered active glacier. (It proved to be the latter, moving downslope at 20-30 mm per year.)
The most significant volcanic deformation was a relatively minor 50 mm expansion across the 500 m wide Main Crater, most of which occurred during increased seismicity in 1982 and during a period of eruptions in 1984. No significant tilt exceeding 20 microradians was recorded and only localised movements attributed to geothermal effects were detected on the crater floor. No short term changes were observed during the declining eruptions in late 1984. The expansion of Main Crater was interpreted as minor inflation across a rift system extending southwest from Main Crater through Side Crater associated with the increased gas and heat flux. There was no evidence for a substantial volume change in magma stored at shallow levels or a blockage in the the conduit beneath the lava lake.
A single publications contains all the information on the surveys and includes the 12 New Zealand references giving more specific information on the survey methods and results and the actual location of the survey stations:
Otway, P.M. Blick, G.H. Scott, B.J. Volcanic deformation monitoring on Mount Erebus: methods and results of geodetic surveys, 1980-1985. In: Volcanological and environmental studies of Mount Erebus, Antarctica. Kyle P.R. (ed) Washington: American Geophysical Union. 1994. pp.57-68 [Antarctic research series: 66] ISBN 0875908756
The actual field observations were recorded in a series of field books, and the computations are on computer printouts and manual calculations, all held by IGNS Science, Wairakei, New Zealand. Please contact Brad Scott B.Scott@gns.cri.nz
BRAD
SCOTT Role:
TECHNICAL CONTACT
Phone:
+64 07 376 0151
Fax:
+64 07 374 8199
Email:
B.Scott at gns.cri.nz
Contact Address:
Wairakei Research Centre
Private Bag 2000 City:
Taupo
Postal Code:
3352
Country:
New Zealand
CEISHA
POIROT Role:
DIF AUTHOR
Phone:
+64 3 358 0200
Fax:
+64 3 358 0211
Email:
c.poirot at antarcticanz.govt.nz
Contact Address:
Antarctica New Zealand
Private Bag 4745 City:
Christchurch
Country:
New Zealand
SHULAMIT
GORDON Role:
DIF AUTHOR
Phone:
+64 3 358 0200
Fax:
+64 3 358 0211
Email:
s.gordon at antarcticanz.govt.nz
Contact Address:
Antarctica New Zealand
Private Bag 4745 City:
Christchurch
Country:
New Zealand
Publications/References
Otway, P.M. Blick, G.H. Scott, B.J. Volcanic deformation monitoring on Mount Erebus: methods and results of geodetic surveys, 1980-1985. in: Volcanological and environmental studies of Mount Erebus, Antarctica.Kyle P.R. (ed) Washington: American Geophysical Union. 1994. pp.57-68 [Antarctic research series: 66] ISBN 0875908756
Blick, G. H. 1986. Site notes - Mt Erebus volcanic monitoring pattern, Immed. Rep. EDS 86/2, Earth Deform. Sect., Dep. Of Sci. And Ind. Res., Lower Hutt, New Zealand.
Blick, G.H. 1987. Mt Erebus, Antarctica, volcanological observations and deformation survey. New Zealand Volcanology Record 15: 52 55.
Blick, G.J. And Scott, B.J. 1986. Volcanic activity and deformation of the summit of Mt Erebus, Antarctica, the 1984 survey with appendix. In: Displacement analysis by P.M. Otway EDS Rep. 101, 39 pp. Earth Deformation Section, Department of Science and Industrial Research, Lower Hutt, New Zealand.
Blick, G.H. And Williams, R.O. 1986. The December 1985 survey of the Mount Erebus volcanic deformation monitoring pattern, EDS Rep. 102, 39 pp. Earth Deformation Section, Department of Science and Industrial Research, Lower Hutt, New Zealand.
Blick, G.H., Otway, P.M. And Scott, B.J. 1989. Deformation monitoring of Mt Erebus, Antarctica, 1980-1985. In Latter, J.H. (Ed.) IAVCEI Proceedings in Volcanology, Vol. 1. Volcanic Hazards. Pp 554-560, Springer-Verlag, New York, 1989.
