An earthquake means shaking of the Earth’s bedrock that can be very strongly destructive to buildings and people. Weak earthquakes shake lamps, but a powerful one can collapse houses or move soil. Seabed earthquakes can cause huge tidal waves that are called tsunamis. Earthquake strength is usually measured on the Richter scale and the level of destructiveness in Mercallin scale. Tremors that have the strength of magnitude of more than seven in the scale, can be very destructive.
Earthquakes take place whenever tectonic plates move in relation to each other, volcanoes erupt, an asteroid collides or land slides. Most earthquakes occur at plate borders in areas where there is also lots of volcanic activity.
Earthquakes can be detected from a far distance with a device called seismometer. Seismic waves are divided into longitudinal and transverse waves.
The strength of the earthquake is usually expressed in units of logarithmic Richter scale. The lowest detectable earthquakes by human senses have three units and the largest that have been measured are over nine points on the scale.
1556 – Earthquake in Shaanxi, China (8.2 units), 830 000 deaths
1755 – Earthquake in Lisbon, Portugal (8.7 pp), 70 000 deaths
1923 – The Great Kanto Earthquake, Tokyo-Yokohama, Japan (8.3 units), 143 000 deaths
1960 – The Great Chilean Earthquake (9.5 points)
1964 – Southern Alaska (9.2 points)
1999 – Earthquake in Izmit, Turkey, 17 480 deaths, 7.5 units of
2003 – Earthquake in Bam, Iran (6.7 points), 45 000 people died, 30 000 injured and 100 000 homeless. Bam, a historic town was completely destroyed.
2004 – Indian Ocean earthquake, coastal Sumatra, Indonesia (9.0 Mw)
2008 – Earthquake in Sichuan, China (7.9 points) 70 000 deaths and 5 million. people homeless.
2010 – Haiti’s earthquake (7.0 units), the loss of life was 28 january secured 170 000, but the government estimates that the final number is 200 000
2010 – Chile earthquake: intensity of 8.8 points, more than 500 deaths
2011 – Earthquake in Japan: a strong earthquake (9.0 units) caused a devastating tsunami.