The Global Geodetic Observing System (GGOS): Backbone for a Solid Earth Observing System for Geohazards Assessment and Disaster Reduction
Hans-Peter Plag(1)
(1) University of Nevada, Reno, Mail Stop 178, Reno, NV 89557, United States
Abstract

An important services that science can provide to society is understanding, predicting, and reducing the vulnerability of society to natural hazards, including geohazards such as earthquakes, volcanoes, rock- and landslides, subsidence, as well as tsunamis triggered by earthquakes, volcanic eruptions, and submarine landslides. In disaster prevention and mitigation, Earth observations are pivotal in at least three aspects: (1) understanding the processes causing these hazards and assessing their risks for planning and mitigation, (2) monitoring the development of hazardous situations and providing a basis for a decision on early warnings, and (3) determining the extent of a disaster as support for rescue and damage assessment.

Geohazards all involve ground deformation. A common observational requirement for these hazards is therefore the ability to measure surface displacements with respect to a well defined reference frame. Information on surface displacements provides a basis for scientific studies of geohazards, hazard assessment, early warning, and disaster assessment. Consequently, geodetic observations play a crucial role in all aspects of disaster prevention and mitigation, including risk assessment and the monitoring of hazardous situations required for the implementation of early warning systems. The observations collected by existing global and regional geodetic networks have already transformed our understanding of geohazards, and these networks will be even more important in the future as their spatial coverage and precision improve. In many regions, observing systems dedicated to geohazards have to be flexible in spatial and temporal resolution, as well as readiness on demand. Therefore, in many parts of the world, dedicated ground-based geodetic networks are needed. In addition to the classical, point-oriented geodetic techniques, two-dimensional imaging techniques such as InSAR are increasingly available allow the monitoring of relevant areas with high spatial resolution, although currently not with the low latency and temporal resolution required for some geohazards applications. Their integration with the geodetic point-techniques provides new means for the monitoring of geohazards.

The Global Geodetic Observing System (GGOS) of the International Association of Geodesy (IAG) is coordinating the geodetic support for the Earth sciences. Building upon the work of the IAG Services, GGOS provides the geodetic infrastructure necessary to support the monitoring of the Earth system and global change research. With the global geodetic reference frames and observations of the variations in the Earth's shape, gravity field, and rotation, GGOS provides fundamental contributions to the Global Earth Observation System of Systems (GEOSS). Geodetic techniques are crucial in the assessment and monitoring and early detection of geohazards, and they will play a pivotal role in early warning systems of such hazards and disasters. The prospect of a fully implemented GGOS is increased security, a better use of resources, and progress towards sustainable development.

The presentation will summarize the current status of the implementation of GGOS in its relevance for geohazards, discuss the main challenges for a better integration of GGOS with other solid Earth observing systems, and use examples to illustrate the versatility of the geodetic techniques for geohazards applications.