Tectonic Rates: The Epicenter Of An Earthquake

One of the most harmful problems that waves cause is earthquakes. Earthquakes injure and kill people, demolish structures, and cause destruction. Recently an earthquake in Ecuador killed 650 people and injured 2,500. A year ago in Nepal there was also a huge earthquake that killed over 8,580 people, one of the worst in history.(13/14)

Earthquakes happen because of tectonic plate movement. When two plates rub against each other, they often get stuck. If pressure builds up, it eventually becomes too great and the rock breaks, releasing waves of seismic energy. The spot underground where the rock breaks is called the focus of the earthquake. The ground above the focus is called the epicenter of the earthquake.(6)

A solution to the injuries caused

They are securely mounted (usually in bedrock) in the earth so when the earth shakes, the case does too. The thing that doesn’t shake is the seismometer. The seismometer is a suspended mass inside the seismograph. Seismographs used to have a pen that would write on a continuously scrolling sheet (seismogram) but modern seismometers work electromagnetically. A large magnet is used as the mass and the case is full of coils of wire. The tiniest of movements of the magnet generate electric signals in the wire, that can be sent to a computer to create a seismogram. Seismographs can detect earthquakes that are too small for humans to feel. In an earthquake, seismic waves move out from the epicenter in every direction. Different types of waves move at different velocity through the earth. Primary waves (P waves) are compression waves, and travel faster than secondary waves (S waves). Because seismographs only measure movement in one direction, seismograph stations have different devices for north-south, east-west, and vertical motions of the ground. These measurements allow scientists to estimate the distance, direction, and magnitude of an

Since these P waves move faster, they serve as a warning. They trigger the seismographs and that allows an earthquake alarm to be raised in any nearby cities. The few minutes that this gives people before the devastating S waves can be enough to save people’s lives.(9) Although scientists haven’t found a way to predict when an earthquake is going to happen before it actually happens, we can use statistics from past earthquakes to figure out where they are likely, and improve building codes in those regions.(11) Another benefit of having many seismographs, is that we can triangulate with the distances from each, to figure out exactly where the epicenter is.(10) People can then immediately send supplies and medical care to the places in most