The earthquake detection is used to warn people because it can be a dangerous natural disaster as earthquakes occur at any time without warning and notification system. What happens when an earthquake happens can be clearly perceived by anyone that the ground start to shake and cause all the objects around you fall. When a large earthquake occurs, it can cause lots of casualties caused by collapse buildings.
Seismo is a term meaning vibrate or violent movement. A tool to measure the ground tremble or earthquake in the ground is a seismometer. In the US alone there are seismic sensors deployed throughout the Americas region. US geological agency, USGS, put about 2,000 sensors to detect earthquakes around America but every earthquake that occurred around the world, is far to reach.
In developed countries such as Japan and Mexico, they use an early warning system to warn citizens of the danger of an earthquake that happened and the hazard like tsunami that might occur. The warning system is to inform the citizens to evacuate. In Japan 2011, the detection of the earthquake has been applied successfully to the area around the city of Sendai to send an early earthquake warning.
For the seismologists to predict when an earthquake will occur by way of fault rupture due to convergent or divergent is very unlikely. What can be done is to detect any fault collapse because at that time the seismic waves would cause vibration wider around the epicenter. That is the way of earthquake detection. Earthquake early warning system is needed for developing countries where there are no earthquake sensors. Haitian state has been shocked by the massive earthquake in 2010 that claimed hundreds of thousands of casualties because there were no earthquake warning systems. This is also the case in countries such as densely populated and prone to earthquakes locations.
Early earthquake warning system in Japan the first time installed on October 2007 was initially useful to mitigate fast train from any fallen tracks. ShakeAlarm is also an early earthquake warning system used at first in Canada to protect transportation tunnels by closing the gate of the tunnel that eventually also be applied in other places such as Canada and in the US and wider locations.
GPS on smart phones technology can also be applied to an quake detection system such as Google Nexus 5. Users should be near the epicenter to detect moderate to large earthquakes. This technology can be a cheap alternative for countries like Japan and Mexico. The least developed countries are well suited to use this technology. The use of multiple GPS smartphone will inform other users when someone is not far from the epicenter.
Seismic wave is generating two vibrations flow such as P which means Prime and S which means secondary. P wave come faster to the surface and S wave arrive late. Results carried by those streams, they could be great. Earthquake detection tool may take several minutes if large earthquakes happen. If others are close to epicenter, they will not get a warning.