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SCAR Bulletin No 134, July 1999

Working Group on Solid-Earth Geophysics

The Working Group met on 20, 23-24 July 1998, and joined the Working Group on Geology on 21 July (and also on 23 and 24 July in the afternoon) in joint discussions. A joint meeting of the 3 Working Groups on Geodesy, Geology, and Solid-Earth Geophysics took place on 21 July.

The meeting was attended by 13 National Representatives and 2 observers.

1. National reports

National Reports were presented by representatives and science programmes were discussed.

2. Sdls - status and future; Antostrat.

An overview on the SDLS structure and the funding resources for producing the data on CD-ROM was presented by A K Cooper. A brief discussion on usage of existing data collection and possible inclusion of other data (eg potential field data) followed. The proposal that ANTOSTRAT should form a subsidiary body of WGs SEG and Geology to preserve SDLS and expertise (as necessary to advise ODP-Antarctic drilling) was presented and deferred for discussion at the joint meeting with the Working Group on Geology.

3. 9th ISAES proposal

The formal invitation by the German National Committee for SCAR to hold the 9th ISAES in Potsdam, Germany in 2003 was presented by the German representative.

4. Liaison with IUGG and CMG

During XXIV SCAR it was noted that the two representatives of IUGG and CMG had been absent for several meetings. The secretary was asked to approach SCAR Executive on the matter.

The need for an appointed liaison representative was discussed and it seemed that there is no apparent neccessity for such a liaison position as it was felt that this is accomodated sufficiently through the presence of working group members during IUGG meetings. However, it remained unclear whether IUGG (and CMG) need a formal liaison with WG SEG. The secretary was asked to approach SCAR Executive again on the matter.

5. Neotectonics

R Bell and D H Elliot presented a proposal to form a new group on Antarctic Neotectonics. The discussion was deferred to the joint meeting of WGs SEG and Geology and a joint meeting of the three WGs SEG, Geology and GGI.

6. Dome C

The Working Group noted the efforts by France and Italy to install a permanent geophysical observatory at the new Antarctic base CONCORDIA (75°S, 124°E).

The earth science programme, essentially dedicated to the study of the Earth Interior, will include:

7. ADMAP

A Meloni reported on ADMAP (Antarctic Digital Magnetic Anomaly Programme). This was launched (1995 workshop ADMAP I, Cambride, UK) to compile and integrate into a digital database all existing near-surface and satellite magnetic anomaly data collected in Antarctica and surrounding oceans south of 60°S.

A workshop (ADMAP II) was held at ING (Istituto Nazionale di Geofisica) in Rome, Italy, from 29 September to 2 October 1997 to consider progress on the development of a digital magnetic database for the production of an Antarctic magnetic anomaly map. More than 30 scientific presentations were prepared and are now undergoing peer-review for publication in a special issue of the journal ANNALI DI GEOFISICA. In addition, the following actions were taken:

The full report of the ADMAP II workshop is available on the website http://io.ingrm.it/free/admap.htm.

The Working Group acknowledged the work of ADMAP and urges again all nations holding magnetic data to contribute so that ADMAP may conclude its work within the initially anticipated 6-year project lifetime.

8. ADGRAV

The goal of ADGRAV (Antarctic Digital Gravity synthesis), presented by R Bell, is to develop an Antarctic gravity data base which will facilitate access to improved high resolution satellite gravity models, in conjunction with airborne, marine, and land based gravity measurements. The proposed gravity data base will complement the parallel projects to develop new continental bedrock (BEDMAP) and magnetic (ADMAP) maps of Antarctica; it will be closely coordinated with the ADMAP and BEDMAP communities. After identifying existing data sets, assessing their quality and agreeing upon protocols for the use of the data contributed to the data base, an interactive method of accessing data via a Web-based interface will be developed. It is intended to present a preliminary map of existing data at the 8th ISAES. The WG welcomed this initiative and encouraged ADGRAVto coordinate closely with ADMAP.

9. Lake Vostok

R Bell reported on the proposal to hold a workshop on Lake Vostok. This issue was deferred to the joint meeting of WGs SEG and Geology.

10. Instrument availability

On behalf of P O'Brien (WG Geology) P Barker suggested compiling a list of (marine) equipment now that geophysical instrumentation is becoming scarce and forcing the possibility of equipment hire.

Working Group members agreed to act as national point of contact for information on the availability of geophysical equipment.

11 Japanese seismic experiment

K Kaminuma (Japan) described seismic reflection and refraction lines that are planned for Enderby Land in 1999-2001, with shots placed on Tonagh sland.

12 Downgrading of Mawson Geomagnetic Observatory

G Burns informed the Working Group about the closing of the magnetic observatory at Mawson Station.

Recalling Recommendation SEG 1998-2, continued from SEG 1996-2, the Working Group is distressed to hear the proposed downgrading of magnetic measurement facilities at Mawson.

13. Working Group rationale

The Working Group considered its function, operation and the related constraints and will continue this discussion at the next meeting.

14. Next Meeting

The Working Group will meet formally during the 8th ISAES in Wellington, New Zealand, in 1999 and again at the XXVI SCAR in Tokyo, Japan in 2000.

Recommendations

SEG 1998-1 (continued from SEG 1996-1)

Recognising the importance of global seismic monitoring in understanding the structure of the deep interior of the earth, the Working Group supports the continued operation of existing broad-band seismographs on the Antarctic continent and encourages the establishment of new ones, both permanent and temporary, in optimal locations.

SEG 1998-2 (continued from SEG 1996-2)

Recognising the importance of high precision absolute measurements of the geomagnetic field in improving understanding of the structure and evolution of the earth's interior, the Working Group encourages the continuation and upgrading of existing magnetic observatories.

SEG 1998-3

Recognising the importance of permanent GPS sites and absolute gravity measurements to geodynamic studies and in providing ground truth for upcoming satellite missions, the Working Group encourages the establishment of new permanent GPS sites and absolute gravity measurements in optimal locations.

SEG 1998-4 (revised from SEG 1996-3)

Recognising that seismic profiling oversnow is essential to an understanding of the geological structure of the Antarctic continent, the Working Group strongly recommends further expansion of this activity.

SEG 1998-5 (revised from SEG 1996-5)

Recognising the value of potential field compilations for understanding continental-scale geologic features, developing new programmes and supporting new satellite missions, the Working Group encourages the completion of the ADMAP digital database and publication of the magnetic anomaly map, as well as the initiation of a synthesis of Antarctic digital gravity data. The Working Group urges all countries holding magnetic and gravity data to contribute.

SEG 1998-6 (revised from SEG 1996-4)

Recognising that swath mapping and high-resolution acoustic profiling are essential for the identification of glacial, neotectonic and other developments in and around Antarctica related to Global Change, the Working Group welcomes the expansion of these activities and recommends their integration with coring and drilling.