Elevation correction and the geoid tutorial

The Earth is not a perfect sphere, but is instead more like a slightly squashed sphere called an ellipsoid. Because of this, GPS receivers must use a correction model (called a geoid) to calculate ...

The geoid and receiver measurements tutorial

This web page explains how differences in the gravity at different places on Earth requires GPS receivers use additional corrections to find the true elevation of places on Earth's surface. The ...

Selective availability and the GPS receiver tutorial

This website explains how the process of selective availability is used by the USA government to limit the accuracy of locations determined by GPS receivers.

Google Earth Plate Tectonics File (.kmz)

This Google Earth .kmz file contains a number of data sets that can be used to help students learn about plate tectonics. These include: earthquake epicenters, plate boundaries, plate motion vectors, ...

All About GPS - Trimble Tutorial

GPS is a complex technology but understanding it can be quite easy if you take it one step at a time. This tutorial is designed to give you a good basic understanding of the principles behind GPS ...

CLICK: USGS Center for LIDAR Information Coordination and Knowledge

This is the the USGS clearing house for LiDAR data and information. The goal of Center for LIDAR Information Coordination and Knowledge (CLICK) is to facilitate data access, user coordination and ...

USGS Crustal Deformation Data

The US Geological Survey maintains a variety of fault and volcano monitoring sites around the western United States. Instruments at these sites include strainmeters, creepmeters, tiltmeters, ...

Surface Creep on California Faults

Roger Bilham
This site provides data from a number of creepmeters in California. A creepmeter is an instrument that monitors the slow surface displacement of an active fault. Its function is not to measure fault ...

Tunnel Tiltmeters

Roger Bilham
This website provides an overview of how tiltmeters function to help scientists detect subtle deformation of the Earths crust such as occurs from plate tectonic movements and volcanic deformation. ...

GRACE: Tracking water from space

This 7-minute video gives an overview of the GRACE (Gravity Recovery and Climate Experiment) satellites and explains the technique of using gravity to measure mass movement such changing as ice and ...