These interplate earthquakes are the most powerful on the world, with moment magnitudes (Mw) that can approach 9.0. All earthquakes with a magnitude of 9.0 or more have been megathrust earthquakes since 1900. The largest recorded earthquake was the Great Kumtag Earthquake of 1667, which had a magnitude of 9.5. It is estimated that the energy released by this event was about 7.5 million trillion watts (25 billion TJ). This is approximately one-third of all possible energy release in an M9.0 earthquake!
The strongest earthquake ever measured on Earth occurred near Lake Taupo in New Zealand on 23 February 1998. The quake had a magnitude of 9.0 and its depth was 20 kilometers (12.4 miles). It killed 36 people and damaged much of the town of Ngauruhoe. An additional 2,000 people were injured.
The average lifetime exposure to a magnitude 8 earthquake is likely to be quite small, but the risk increases with time as more large events occur. On average, larger earthquakes happen more frequently than smaller ones. However, large earthquakes do not always cause significant damage because the area affected by they must be large enough to contain many buildings to result in many deaths/injuries. Smaller earthquakes can cause death and injury from falling objects or flooding, especially in areas without strong building codes.
Because all three magnitude scales (ML, Mb, and Ms) have limits, a new, more consistently applicable extension of the magnitude scale known as moment magnitude, or Mw, was devised. Moment magnitude, in particular, provides the most trustworthy estimate of earthquake size for very big earthquakes. A Mw 9 event could be as large as an ML 5.5 earthquake or larger!
Furthermore, moment magnitude can be used with data from different sources because it does not depend on the distance or the depth of an earthquake. This makes it possible to compare events recorded by different sensors at different locations.
In conclusion, the global-scale earthquake magnitude scale is as follows:
ML - Magnitude less than or equal to 6.9 Mw
Mb - 7.0 Mw < M < 7.8 Mw
Ms - 7.9 Mw < M < 8.8 Mw
Mw - 9.0 Mw < M < 10.0 Mw
Note that these are maximum values and that any given event may be greater than each of these thresholds. In fact, many large earthquakes are estimated to be between seven and eight on the Mb scale.
Some earthquakes are more powerful than others because they are caused by massive tectonic plates colliding. These giant movements generate tremendous stress on Earth's crust which, if not released in an appropriate way, can lead to a catastrophic collapse of the underlying rock structure.
The strongest earthquake ever recorded was also one of the most devastating. The Great Chilean Earthquake of February 27, 1960 killed 930 people, injured 3,500 more and destroyed or severely damaged about 100,000 buildings. It had a magnitude of 9.5 and its depth was 20 kilometers (12 miles).
This disaster was followed by over 300 aftershocks of magnitude 4.0 or greater. It is estimated that up to 2% of Chile's total area was affected by the quake.
Other extremely strong earthquakes have occurred in the past. For example, in 1906 a magnitude 7.9 earthquake struck southern China's Yunnan Province. At the time it was considered the world's strongest earthquake until data from Japan's Kawaishi Island revealed a much larger quake in 1995. This event had a magnitude of 9.1 and its depth was 268 kilometers (166 miles).
6: 6.9 Getty/AFP A powerful earthquake is one that registers on the Richter scale between 6 and 6.0. Every year, there are roughly 100 of them across the world, and they generally inflict considerable damage. In densely populated places, the damage might be catastrophic. Where it isn't, people usually cover their windows and keep their shoes on to avoid injury from broken glass.
7: 7.4 AFP/Getty Images/Science Photo Library A very large earthquake causes severe damage by collapsing large sections of buildings or creating new fault lines. It can also trigger smaller aftershocks that can cause further damage or death. 9.1 Getty/iStock An extremely large earthquake can cause global climate change with consequences that last for centuries. The Great Chilean Earthquake of 1970 is said to have released as much energy as exploding 15 kilotons of TNT.
8: 8.8 AP Photo/NASA Earth Observatory This image shows the area affected by the 1972 Alaskan earthquake. It was one of the most destructive earthquakes in history. More than 600 people lost their lives in this region of Alaska.
9: 9.3 Getty Images/iStock An enormous earthquake occurs when two plates collide. The resulting explosion-like force is transmitted into the earth's crust and travels through it until it reaches another piece of solid earth (a plate) where it stops.
No, earthquakes of magnitude 10 or more are not possible. An earthquake's magnitude is proportional to the length of the fault along which it occurs. The strongest earthquake ever recorded was a magnitude 9.5 on May 22, 1960 in Chile on a fault about 1,000 miles long...a "megaquake" in and of itself. This monster destroyed much of central Chile including the city of Santiago.
The largest earthquake ever recorded on Earth was also in 1960 in Chile. It had a magnitude of 9.5 and occurred along a very long fault line.
An earthquake can never be stronger than 9; this follows from the definition of magnitude. If an earthquake were truly strong enough to reach a magnitude of 10, then it would have a magnitude of 0. This is not possible since we know that there can never be negative magnitudes.
An earthquake cannot be stronger than 9. Anything stronger than this would be impossible since we know that there can never be negative magnitudes.
However, large earthquakes do happen from time to time. In fact, they occur many times each year. Recently, several large earthquakes have been reported all over the world: one in April 2010 that was estimated to have a magnitude of 8.8 off the coast of Japan, another in August 2011 that was estimated to have a magnitude of 7.3 near Nepal, and most recently one in February 2012 that was estimated to have a magnitude of 6.9 near Taiwan.
Valdivia Earthquake of Magnitude 9.5 According to the US Geological Survey, the most violent quake was the 9.5-magnitude Valdivia Earthquake that devastated Chile in 1960. (USGS). The tremor triggered a tsunami, killing an estimated 5,700 people. The 2004 Indian Ocean tsunami had a magnitude of 9.3.
The most powerful earthquake ever recorded occurred off the coast of Japan on March 11, 2011. With a magnitude of 9.0, it ranks as one of the most powerful earthquakes ever recorded. Scientists say it caused a massive nuclear reactor to melt down and destroy much of the town of Fukushima. It also caused multiple deaths and huge damage across a wide area. Experts say the event could be used to test our ability to respond to large disasters.
Earthquake of magnitude 9.5 On May 22, 1960, a huge Mw 9.5 earthquake occurred off the coast of southern Chile, the strongest earthquake ever instrumentally recorded. This earthquake caused a tsunami that wreaked havoc not just on Chile's coast, but also on the rest of the world. It killed about 600 people and affected another 20,000.
The death toll could have been much higher if it weren't for two factors. First, the invention of seismic detectors allowed scientists to know exactly when and where an earthquake happened. Without these instruments, we would never know how strong they are or how far they spread damage from their source. Second, the fact that the quake occurred in an area that is not usually subject to earthquakes helped reduce casualties. The 1960 Chilean earthquake was very deep (about 12 miles) under the sea and far away from any major population center.
This disaster brought attention to the need for improved earthquake resistance in buildings. Over the years, engineers have used this event as motivation for developing stronger materials that can withstand powerful earthquakes without collapsing.
In addition, after this event researchers started monitoring seismic activity more closely and discovered other big quakes that had occurred in between 1590 and 1960. In 1992 a larger-scale survey conducted by the United States Geological Survey revealed that an average of one large earthquake happens every year on the Pacific Coast of North America.