Student Activity
Meet Geodesy
The Science behind GPS
Introduction
On December 23, 2003 at 11:15 AM, a magnitude 6.5 earthquake shook the town of Paso Robles, California. Two people were killed, and many historic building were severely damaged. Three days later, the city of Bam in southeastern Iran was shaken by a magnitude 6.6 earthquake, which killed more than 30,000 people and damaged more than 85% of the city’s buildings. In the days following these disasters, many news reports shared a common theme. One of the scariest things about earthquakes is that they strike without warning. Some reports also commented that the loss of life due to hurricanes has been greatly reduced because we are able to predict when and where these storms are likely to strike. But earthquakes are much less predictable.
You already know that earthquakes are caused by movements of the Earth’s crust. You may also know that these movements can be caused by volcanic activity or when blocks that make up the Earth’s crust move along fractures (called faults) between the blocks. Are strong earthquakes preceded by smaller movements of the Earth’s surface that might give some warning of larger movements? Is there any way to systematically monitor movements of the Earth’s surface?
The science known as geodesy involves measuring changes in the location of points on the Earth’s surface, as well as the Earth’s size and shape. In this lesson, you will investigate methods of determining location on the Earth's surface in order to develop an understanding of how the global positioning satellite system works.
Access Meet Geodesy Materials
: Follow your teacher's directions.
: At the proper time, insure your computer is Internet-enabled and you have an appropriate browser installed.
: Power on the computer. Launch the browser. Point the browser to the web address given by your teacher.
YOUR TURN
More Lessons from the Sky, 2014, Satellite Educators Association Meet Geodesy 7