Rescuers search for survivors and victims amid destroyed buildings in Nurdagi, in the hard hit region of Gaziantep, on February 12, 2023, after a 7.8 magnitude earthquake struck the border region of Turkey and Syria earlier in the week. LEHTIKUVA / AFP

Science and technology

While the death toll and destruction of the recent earthquake in Turkey and Syria dominate the news, many wonder how strong the quake was and what the scale used to measure earthquakes means.

The Richter scale is a tool used to measure the magnitude of earthquakes. Developed in the 1930s by seismologist Charles Richter, the scale ranges from 0 to 10.

Many people do not realize that the Richter scale is logarithmic in nature. This means that each increase in whole number on the Richter scale represents a tenfold increase in the earthquake's amplitude or the size of its seismic waves, so a 7 magnitude Richer earthquake is 10 times stronger than a 6 magnitude.

It's worth noting that the Richter scale is not always the best way to measure earthquakes, as it was designed to work best for smaller earthquakes in the local area of California, where it was developed. For larger and more distant earthquakes, other scales, such as the Moment Magnitude Scale, are often used. However, the Richter scale remains a widely recognized measure of earthquake magnitude and is still used in many contexts.

The strongest earthquake ever recorded on the Richter scale occurred on May 22, 1960, in Valdivia, Chile. This earthquake had a magnitude of 9.5 and caused widespread damage and loss of life. It is also the largest earthquake ever recorded in the world. Following the Valdivia earthquake, several other earthquakes have also registered high on the Richter scale. Here are some of the strongest earthquakes in recorded history, listed in order of their magnitude on the Richter scale:

Valdivia, Chile, 1960 - 9.5
Prince William Sound, Alaska, 1964 - 9.2
Sumatra-Andaman Islands, Indonesia, 2004 - 9.1
Kamchatka, Russia, 1952 - 9.0
Maule, Chile, 2010 - 8.8
Rat Islands, Alaska, 1965 - 8.7
Northern Sumatra, Indonesia, 2005 - 8.6
Andreanof Islands, Alaska, 1957 - 8.6
Ecuador, 1906 - 8.8 (est.)
Tōhoku, Japan, 2011 - 9.0

The recent earthquake of Feb 6, 2023, in Turkey and Syria was a 7.8 Richter. The last 7.8 magnitude earthquake recorded in the last 10 years occurred on April 25, 2015, in Nepal. The earthquake, which was the worst to hit the country in more than 80 years, killed over 8,000 people and injured more than 21,000. The 7.8 magnitude quake is the worst to hit Turkey since 1939 when an earthquake in the east of the country killed around 33,000 people.

There have been several other major earthquakes that have caused significant damage and loss of life, including the 2010 Haiti earthquake (magnitude 7.0, over 200,000 dead), the 2011 Tohoku earthquake and tsunami in Japan (magnitude 9.0, over 15,000 dead), and the 2016 Ecuador earthquake (magnitude 7.8, over 670 dead).

The destruction and loss of human life are also directly related to the concentration of urban areas where the earthquake occurs and the time of the day. The earthquake last week happened around 4 am when almost every resident of the area where at home sleeping.

There are several countries and urban areas around the world that are built on seismically unstable areas. Here are some examples:

Japan: Japan is located on the Pacific Ring of Fire, which is one of the most seismically active areas in the world. As a result, Japan is prone to earthquakes, volcanic eruptions, and tsunamis. Despite this, Japan is densely populated and has many major cities built on seismically unstable areas, including Tokyo, Yokohama, and Osaka.

California, United States: California is located on the San Andreas Fault, which is a major fault line that is responsible for many earthquakes in the region. Despite this, California is home to several large cities, including Los Angeles, San Francisco, and San Diego.

Nepal: Nepal is located in the Himalayan region, which is prone to earthquakes and landslides. Despite this, Nepal is home to several major cities, including Kathmandu, which was devastated by a major earthquake in 2015.

Mexico City, Mexico: Mexico City is located on an ancient lakebed that is prone to liquefaction during earthquakes, which can cause significant damage to buildings and infrastructure. Despite this, Mexico City is one of the most populous cities in the world and has a rich history and cultural heritage.

Istanbul, Turkey: Istanbul is located near the North Anatolian Fault, which is a major seismic fault that is prone to earthquakes. Despite this, Istanbul is one of the most populous cities in Europe and has a long history of settlement in the area.

The North Anatolian Fault is a major geological fault line in Turkey that runs parallel to the Black Sea coast. The fault is responsible for many large earthquakes in the region and is one of the most active and dangerous faults in Turkey.

The North Anatolian Fault is a right-lateral strike-slip fault, which means that the two tectonic plates on either side of the fault move horizontally past each other. The fault extends for over 1,500 km from eastern Turkey to the Aegean Sea and is divided into several segments that can rupture independently, producing earthquakes of varying magnitudes.

The North Anatolian Fault has produced several major earthquakes in the past, including the 1939 Erzincan earthquake, the 1999 Izmit earthquake, and the 2011 Van earthquake. The 1999 Izmit earthquake was particularly devastating, with a magnitude of 7.6 and a death toll of over 17,000 people.

The North Anatolian Fault is closely monitored by seismologists and geologists, and there are ongoing efforts to improve earthquake preparedness and risk reduction in the region. This includes improving building codes and standards, retrofitting older buildings to make them more earthquake-resistant, and educating the public about earthquake safety and preparedness.

Despite these efforts, the North Anatolian Fault remains a significant seismic hazard, and the potential for a major earthquake in the region is a serious concern for public safety and infrastructure resilience in Turkey

Overall, many countries and urban areas around the world are built on seismically unstable areas, which can pose significant risks to the safety and wellbeing of their populations. It is important for these areas to be prepared for earthquakes and other natural disasters and for measures to be taken to reduce the risk of damage and loss of life.