Establishment of an Absolute Gravity Network in East-Asia and Precise Monitoring of Gravity Changes

我们参与了国际天文学联合会的亚太空间地球动力学项目合作活动和亚洲及太平洋地理信息系统基础设施常设委员会(PCGIAP)的工作计划，合作建立了东亚和东南亚绝对重力标准台网(AGSSN-ESEA)和FG-5绝对重力仪。在2002年至2005年期间，我们已经在武汉、南宁、上海、北京、昆明、拉萨、香港乌鲁木齐、西安和西宁的中国、台湾的新竹、印度尼西亚的万隆、日惹慈农和蓬田纳克、马来西亚的吉隆坡和哥打基纳巴卢、泰国的曼谷和正迈、菲律宾的马尼拉和日本的京都、江西、松下、神冈、木户、麻生、水上和那霸，按μGal的顺序测定了绝对重力值。在这次活动中，我们在印度尼西亚、马来西亚和菲律宾进行了首次AG测量，并为建立这些国家的国家重力标准做出了贡献。作为这一活动在南半球的延伸，我们于2003-2004年在澳大利亚的珀斯和堪培拉以及南极的西奥瓦站进行了绝对重力测量。通过比较武汉、北京、香港、新竹和京都的不同FG-5仪器获得的AG值，发现每个仪器的测量值最大相差11μGal。在武汉、万隆、京都、Esashi、Matsushiro和Kamioka，我们通过SG和AG仪器的相互比对，确定了SG校准因子，精度在0.1%量级以内。我们预计，通过AGSSN-ESEA站每隔5-10年的重复AG测量，可以探测到大陆和岛弧之间的相对垂直运动在1厘米量级。

Taking part in the Asia-Pacific Space Geodynamics (APSG) Project cooperation campaigns in IAG and the work plan in the Permanent Committee on GIS Infrastructure for Asia & the Pacific (PCGIAP), we have collaborated to establish the Absolute Gravity Standard Station Network in East Asia and South-East Asia (AGSSN-ESEA) with FG-5 absolute gravimeters. During the period from 2002 to 2005, we have already determined absolute gravity values in the order of μGal at Wuhan, Nanning, Shanghai, Beijing, Kunming, Lhasa, Hong-Kong Wulumuqi, Xi'an and Xining in China, Hsinchu in Taiwan, Bandung, Yogyakarta Cibinong and Pontianak in Indonesia, Kuala Lumpur and Kota Kinabalu in Malaysia, Bangkok and Cheng-Mai in Thailand, and Manila in Philippines as well as Kyoto, Esashi, Matsushiro, Kamioka, Muroto, Aso, Mizunami and Naha in Japan. In this campaign, we performed first AG measurements in Indonesia, Malaysia and Philippines and contributed to establish national gravity standards in these countries. As an extension of this campaign in the southern hemisphere, we have conducted absolute gravity measurements in Perth and Canberra in Australia, and the Syowa Station in Antarctica in 2003-2004.As a result of comparison of AG values obtained from different FG-5 meters in Wuhan, Beijing, Hong Kong, Hsinchu and Kyoto, it was revealed that difference in measured values depending on each instrument is 11μGal at the most. In Wuhan, Bandung, Kyoto, Esashi, Matsushiro and Kamioka, we have determined SG calibration factors within the accuracy of the order of 0.1% from inter-comparison of SG and AG meters.We are expecting that relative vertical movements between the continent and island arc can be detected in the order of 1cm by the repeated AG measurements at stations in AGSSN-ESEA at interval of 5 to 10 years.