our knowledge of the dynamics of the Earth, (4) promote international scientific exchange and cooperation, and (5) contribute to raising the scientific research level in the developing countries.

Scientific Background and Motivation

The Asian-Pacific area, primarily the western Pacific boundary zone including China, Japan, and Southeast Asia, and the northern Indian Ocean boundary zone including the Tibetan Plateau of China and Southeast Asia, is the convergence zone of four plates: Eurasian, Pacific, Philippine and Indo-Australian. The region also includes a major portion of the tectonic system that is responsible for new activity in the Round-Pacific and the Alps-Himalayas mountain-building zones. The area is characterized by complex tectonics, violent crustal motion, frequent and fierce earthquakes, and devastating volcanic activity. In this area there is dense population, rapidly developing economics, and yet frequent and serious natural hazards (earthquakes, volcanic eruptions, sea immersion, etc.). Therefore this area is one of the most appropriate and urgent regions for research in tectonic and crustal motion, local deformation, sea-level change and their effects on the existing human environment. The main objective of the Asia-Pacific Space Geodynamics (APSG) Program is to unite all relevant activities in the region into a cooperative research project in plate tectonic, crustal motion and deformation, and sea level change in the area. This will provide a synergistic umbrella for scientists in the region to cooperate and to contribute to the better understanding of the processes involved and better prediction of major disastrous events.

All countries in the Asia-Pacific area have been urged to join in this project, while countries outside the area are warmly invited to participate. The project will promote international academic exchange and scientific cooperation, and will contribute to the scientific research level of the developing countries in this area.

The primary objectives of study for the APSG are to:

     1. measure and monitor, using space techniques, the relative motion between the Eurasian, Pacific, Philippine, and Indo-Australian plates including the plate tectonic motion along the boundaries, as well as local crustal deformation;

     2. study the evolution and dynamics of the crustal motion of the island-arc system in the Western Pacific boundary zone and the mountain-building zones of the Tibetan Plateau and Southeast Asia;

     3. measure and monitor sea-level change in the Asia-Pacific region using space techniques including altimetry and tide gauge data to study the characteristics and causes of the fluctuations in global sea surface;

     4. investigate the dynamics of the Earth as a whole (Earth rotation, gravity changes, etc.) and the mass motions within each layer (including the atmosphere, oceans, lithosphere, mantle, and the core) and their dynamic relations; and

     5. investigate natural hazards (earthquakes, volcanic eruptions, sea immersion, etc.) in the region as well as their relation with various Earth motions, and provide basic information for the prediction of natural disasters.

Historical Background

A proposal to organize the APSG was first presented at the WEGENER meeting in St. Petersburg in June 1994. The proposal was then endorsed by the United Nations Expert Symposium on Space Technology and Application for Sustainable Development in Beijing China in September 1994, and included as a Symposium recommendation to the Ministerial Conference on Space Applications for Development in Asia and the Pacific under the United Nations Economic and Social Commission for Asia and the Pacific (ESCAP).

The APSG was then compiled into an Action Program for Chinese Space Applications for sustainable Development. Presentations were made at the Third Asian-Pacific Radio Telescope Meeting at Urumqi, China in October 1994 and at the Ninth International Workshop on Laser Ranging Instrumentation held at Canberra, Australia in November 1994. At a meeting held after the Workshop in Canberra, representatives from Australia, China, Japan, and the USA expressed their strong support for the APSG project and agreed to form a Steering Committee chaired by Prof. Ye Shuhua with membership from the above five countries. They agreed that a detailed plan should be prepared for submission to the International Association of Geodesy (IAG) at its General Assembly in Boulder, Colorado, USA in July 1995. The IAG accepted the project and recommended that it be supported by local institutions and international cooperating agencies.

The first International Meeting of the APSG was held in Shanghai in June 1996. Attendees from Australia, China, Germany, Hong Kong, Indonesia, Japan, Russia, South Korea, and the USA agreed that APSG should be set up in a manner similar to WEGENER, where the scientific research activities would be organized and coordinated by Scientific Working Groups, and measurement expertise would be represented by a Measurement Working Group organized into technique panels. Three Science Working Groups were organized to begin activities:

      1. Crustal Motion and Dynamics of the Tibetan Plateau

      2. Crustal Tectonic Motion of the Western Pacific Volcanic-Seismic Belt

      3. The Impact of Sea Level Variations on the Asia-Pacific Region

Five Measurement Panels were also organized:

      1. GPS (and other radio satellite tracking methods)

      2. Gravity

      3. Synthetic Aperture Radar

      4. Satellite Laser Ranging

      5. VLBI

The first meeting provided a venue for scientists working in the relevant disciplines in the Asia-Pacific region to meet, discuss their work, and plan activities that would benefit from a synergistic umbrella supported by key institutions and agencies in the region.

Plan for the Meeting in Tahiti

The objectives of this second meeting were to:

  1. strengthen the Science Working Groups established at the Shanghai Meeting in May 1996 so that they   can function as planning and organizational entities to:

	coordinate present measurement and analysis activities; and
	develop and implement new programs;

     2. strengthen the Measurement Technique Panels so that they would be effective resource entities to support the science activities; and

     3. strengthen the APSG organization so that it can provide the necessary umbrella and infrastructure to conduct the scientific programs.

The plan for the meeting was to:

     1. Review and discuss related scientific activities currently underway within the region;

     2. Review the status of organization and planning activities for the Science Working Groups;

     3. Review the status and planning of measurement technique development and deployment; and

     4. Continue collaborative planning for coordinated program implementation.

In their deliberations, the Science Working Groups were asked to address the following questions:

	What programs are currently underway?
	What programs are being seriously planned?
	What are the compelling science issues that we should be addressing?
	What are the natural hazard issues that we should be addressing? Are we addressing any of these?
	What can we reasonably expect from the programs underway?
	What important topics have not been addressed?
	What would be required to address them?
	Are there synergies and bases for cooperation among groups that might enhance our productivity?
	How might we proceed?
	What agencies might be interested in funding some of these activities?

The Measurement Technique Panels were asked to address the following questions:

	What is new and relevant?
	What systems are currently operating in the region?
	What are the serious plans for new systems?

Fifty-two participants from Australia, China, France, French Polynesia, Germany, Indonesia, Japan, Hong Kong, Korea, New Caledonia, Russia, Taiwan, and the United States attended (see the Attendance List). All participants in the meeting were required to join a Science Working Group or a Measurement Technique Panel. Each was asked to give a short presentation on his work in the region along with current plans (see the Program Agenda). Conveners of the Science Working Groups were asked to report on the progress-to-date in organizing their Working Groups and Panels, and in the development of their charters and plans. All Science Working Groups and Measurement Panels were required to provide a draft summary report addressing the above issues before the close of the meeting and a final version 30 days later.