Bulletin of the GSI(Vol.58)

The Long-Term Plan for Basic Surveys (hereinafter referred to as "Long-Term Plan") is a plan on the Basic Surveys, which is conducted by the Geospatial Information Authority of Japan (hereinafter referred to as "the GSI") as the survey that serves as the basis for all other surveys, and Long-Term Plan shall be stipulated by the Minister of MLIT based on Article 12 of the Survey Act.

Long-Term Plan shall be established in order to achieve the purpose of the Survey Act, which is to avoid redundancy in surveys and to assure survey accuracy by publicly announcing the target and scale of the Basic Surveys in advance.

According to the Basic Act on the Advancement of Utilizing Geospatial Information (Act No. 63 of 2007 - hereinafter referred to as the "NSDI Act") enacted in 2007, information that represents the position of specific point or extent in geospace and its associated information are defined as geospatial information, and it is considered extremely important to promote its advanced utilization for creating an economic society in which people can live their lives security and abundantly.

This revision of Long-Term Plan aims to clarify the policies, for which GSI should take initiative in implementing, in order to realize an advanced geospatial information utilization society in which geospatial information including survey results will be used more effectively based on the newly enacted NSDI Act in addition to the Survey Act.

Aiming to define the basic direction for research and development (R&D) to be performed by the Geospatial Information Authority of Japan (GSI), this plan clarifies what kind of R&D should be executed by the GSI in the future as well as necessary policies for the execution of such R&D in light of social needs for R&D based on the “Basic Plan for the Advancement of Utilizing Geospatial Information” (hereafter, “Basic Plan for the AUGI”), the “Long-Term Plan for Basic Survey,” the “Promotion of Research and Observation Program for Earthquake and Volcanic Eruption Prediction (proposal)” suggested by the Council for Science and Technology, in addition to achievements and issues of the previously-conducted plan, the “GSI Research and Development Five-year Plan.”

The period of this plan is set to five years from FY2009 to FY2013 in order to maintain the continuity of R&D, while taking expected changes in social conditions and rapid progress in technologies into consideration. Note that, however, this plan will be partially or entirely revised as needed, even within the period.

The GSI aims to solve various issues through this plan within the planned period and make every effort to achieve this goal.

This paper introduces the “Active Fault Map in Urban Areas”, a series of 1:25,000 scale maps showing detailed locations of active faults in urban areas published by the Geospatial Information Authority of Japan (GSI). The 1995 South Hyogo Prefecture Earthquake in the local district of Kobe prompted GSI to obtain more information about inland active faults and to develop Active Fault Maps. Since then, GSI has continued to publish these maps, with 147 maps published as of 2010. The maps describe active faults, active flexures, active folds, and terrain classifications at a scale of 1:25,000. Since 2006, scanned map images and GIS data were also published on the Japanese GSI website. GSI will encourage further improvement of the Active Fault Map in Urban Areas.

This paper summarizes the effect of various noises on GEONET height time series and demonstrates how the state-of-art analysis technique can improve its quality with the results evaluated by simulations and actual observations. Three factors that may affect the GPS-derived height time series are investigated: 1) mismodeling of atmospheric delays; 2) load deformation by the atmosphere; and 3) load deformation by the ocean. It is found that: 1) the use of conventional mapping functions that are used in the current GEONET routine analysis may introduce spurious annual height variations up to 3mm, and these spurious signals can be considerably mitigated with the use of mapping functions based on numerical weather models; 2) annual height variations caused by the atmospheric loading are up to 3mm; and 3) the annual variations caused by oceanic loading deformations get larger toward the south, reaching 3mm in the Nansei Islands. It is confirmed that when these corrections are applied in the GPS analysis of GEONET data, the annual height variations of GEONET stations are largely reduced. Hence, it may now be possible to detect even these small movements related to the earthquake/volcanic activities that were formally obscured by the annual height noises, offering a hope that more accurate disaster prevention information could be provided.