11
The Modified Mercalli Intensity (MMI) level of the Japan earthquake on March 11, 2011, was around VII to IX, varying across different locations. The earthquake caused widespread damage and triggered a devastating tsunami that led to significant destruction and loss of life.
An intensity of VII on the Modified Mercalli Intensity scale can cause considerable damage to poorly built buildings. This level of intensity typically leads to partial collapse of structures with a likelihood of extensive damage.
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According to the US Geological survey, the maximum intensity of the magnitude 9.5 Chilean earthquake of 1960 was rated as XI on the Modified Mercalli Intensity scale which are described as very disastrous or extreme events which are likely to cause significant damage to structures. Please see the related link for details.
About no. 9
The Modified Mercalli intensity scale ranges from 1 to 12 (I - XII), with XII being described as cataclysmic. This leads to total destruction of nearly all structures. The ground surface will potentially have permanently changed level by several metres. The ground's surface moves with visible waves or ripples while the earthquake is occurring.
1X = 9
An earthquake with an intensity level of XII on the Modified Mercalli Intensity scale can cause total destruction in the affected area. Buildings, bridges, and infrastructure may collapse, resulting in widespread devastation. There may also be landslides, ground ruptures, and tsunamis triggered by such a powerful earthquake.
According to the US Geological survey the Haitian Earthquake had the capacity to cause some minor structural damage to buildings as far away as 300 km from the Earthquakes epicentre (level V or 5 on the Modified Mercalli Intensity scale. It was felt by humans as far away as Guantanamo in Cuba (level III or 3 on the Modified Mercalli Intensity scale) and would most likely have been detected by seismometers all over the world. Please see the related question and link.
The US Geological Survey provide a contour map of earthquake intensity for the earthquake that occurred on the 12th of January, 2010. This indicates that the highest intensity (perceived shaking) with a level of 10 (X) on the Modified Mercalli Intensity Scale occurred in Grand Goave (population 5000). The Haitian capital Port-au-Prince suffered an intensity 9 event. The scale indicates that at this intensity structures will suffer heavy to very heavy damage. Please see the related links and question.
MM Intensity- XI
The amount of shaking produced by an earthquake at a given location is called the intensity. It is measured on the Modified Mercalli Intensity (MMI) scale, which quantifies the level of shaking experienced by people and structures during an earthquake.