Monday, February 2, 2015

Geodesy in the 21st Century

Geodesy is the study of the Earth's physical nature, including its shape, orientation, size, and gravitational field. It is a relatively new field that relies on technological advancements, especially satellite and space measurement technologies (starting with the launch of Sputnik in 1957). It relies on accurate measurements using fixed constants usually perceived from space, whether that be the north and south pole or cosmological orbits of the moon and planets.

There are many techniques used to get centimeter accurate measurements, including widely know ones such as global positioning system (GPS) and light detection and ranging (LIDAR). Using them, scientist can find global estimates of sea level change or map the motion of tectonic plates. Also, mixing two techniques such as the primarily elevation based LIDAR and rainwater precipitation sensitive GNSS (similar to GPS) can be used to see how aquifers recharge after rainfall.

The only way information such as the graph above can be made is because of the precise and repetitive nature of satellite orbits. Data from the 1980s can be used with more current data to provide information on the extent of surface deformation due to plate movement, this in turn can provide insight into the slight changes in Earth's gravitational fields that can only be seen in large scale.

Another inference made came from the the use of GPS measurements of glacial movement and loss. After the melting of ice caps in the last ice age the Earth's mantle and crust warped due to the changes in mass above them. Measuring this change has led to the determination of how viscous the mantle is.

Geodesy is also important in understanding and predicting natural disasters and subtle changes in lived in areas. Multiple threats can impact places like Thailand where the constantly rising sea levels are magnifying the impact of normal floods.

 Some other applications (above), including aquifer response to water pumping and landslides along crests.

Source: Wdowinski, S., & Eriksson, S. (2009). Geodesy in the 21st Century. Eos, Transactions American Geophysical Union90(18), 153-155.


  1. Since the introduction of technologies such as geodesy and LIDAR, we are able to measure and predict so many more things that impact a lot of people in the world, like the natural disaster prediction mentioned. I wonder if, since 2009 when this paper was published, any new technologies or improvements in the field of geodesy have been made and if so, what do those new innovations allow us to do?

  2. Its interesting how such large scale technology like LiDAR and GPS can help us view things both large and small scale. The use of these technologies is allowing us to get a real understanding and perspective of what the world actually does, and did, look like. We are now able to access much more information about the physical properties and characteristics which in turn can aid in research in other areas such as archaeology and history.