From the introduction section:
The Quake-Catcher Network: Cyberinfrastructure Bringing Seismology to Homes and SchoolsEarthquake safety is a responsibility shared by billions worldwide. The Quake-Catcher Network (QCN) provides software so that individuals can join together to improve earthquake monitoring, earthquake awareness, and the science of earthquakes. The Quake-Catcher Network (QCN) links existing networked laptops and desktops in hopes to form the world’s largest and densest earthquake monitoring system. Costs for this network are minimal because the QCN uses 1) strong motion sensors (accelerometers) already internal to many laptops and 2) low-cost universal serial bus (USB) accelerometers for use with desktops. The QCN is built around the Berkeley Open Infrastructure for Network Computing (BOINC!), which provides free software to link volunteer computers together for a single scientific goal.Learn more about the Desktop Network.Learn more about the Laptop Network.The QCN provides a natural way to engage students and the public in earthquake detection and research. This project places USB-connectable sensors in K-12 classrooms as an educational tool for teaching science and a scientific tool for studying and monitoring earthquakes. Through a variety of interactive experiments students can learn about earthquakes and the hazards that earthquakes pose. For example, students can learn how the vibrations of an earthquake decrease with distance by jumping up and down at increasing distances from the classroom sensor and plotting the decreased amplitude of the seismic signal displayed on their computer.
Here is a layman's description of the system.
The type of sensors being used are low cost three way accelerometers. If you take a look at the usage, you'll find that a quake better not hit on saturday or sunday.