Moment magnitude scale in the context of "365 Crete earthquake"

The Great Kantō Earthquake (Japanese: 関東大地震, romanized: Kantō daijishin or 関東大震災, Kantō daishinsai) was a megathrust earthquake that struck the Kantō Plain on the main Japanese island of Honshu at 11:58:32 JST (02:58:32 UTC) on Saturday, 1 September 1923. It had an approximate magnitude of 8.0 on the moment magnitude scale (M_w), with its epicenter located some 100 km (62 mi) southwest of the capital Tokyo. The earthquake devastated Tokyo, the port city of Yokohama, and surrounding prefectures of Kanagawa, Chiba, and Shizuoka, and caused widespread damage throughout the Kantō region.

The event was a complex disaster, with modern research indicating it consisted of three consecutive shocks in the span of several minutes. The initial megathrust event in Kanagawa Prefecture was followed three minutes later by a magnitude 7.2 earthquake centered beneath Tokyo Bay, and two minutes after that by a magnitude 7.3 shock in Yamanashi Prefecture. Fires, exacerbated by strong winds from a nearby typhoon, spread rapidly through the densely populated urban areas, accounting for the majority of the devastation and casualties. The death toll is estimated to have been between 105,000 and 140,000 people, including tens of thousands who went missing and were presumed dead. Over half of Tokyo and nearly all of Yokohama were destroyed, leaving approximately 2.5 million people homeless. The disaster triggered widespread social unrest, including the Kantō Massacre, in which ethnic Koreans and others mistaken for them were murdered by vigilante groups based on false rumors.

The April 2015 Nepal earthquake (also known as the Gorkha earthquake) killed 8,962 people and injured 21,952 across the countries of Nepal, India, China and Bangladesh. It occurred at 11:56 Nepal Standard Time on Saturday 25 April 2015, with a magnitude of M_w 7.8–7.9 or M_s 8.1 and a maximum Mercalli Intensity of X (Extreme). Its epicenter was east of Gorkha District at Barpak, Gorkha, roughly 85 km (53 mi) northwest of central Kathmandu, and its hypocenter was at a depth of approximately 8.2 km (5.1 mi). It was the worst natural disaster to strike Nepal since the 1934 Nepal–India earthquake. The ground motion recorded in Kathmandu, the capital of Nepal, was of low frequency, which, along with its occurrence at an hour when many people in rural areas were working outdoors, decreased the loss of human lives.

The earthquake triggered an avalanche on Mount Everest, killing 22 people, the deadliest incident on the mountain on record. The earthquake triggered another huge avalanche in the Langtang valley, where 250 people were reported missing.

The 1956 Amorgos earthquake occurred at 03:11 UTC on July 9. It had a magnitude of 7.7 on the moment magnitude scale and a maximum perceived intensity of IX on the Mercalli intensity scale. The epicentre was to the south of the island of Amorgos, the easternmost island of the Cyclades in the Aegean Sea. There was significant damage on Amorgos and the neighbouring island of Santorini. It was the largest earthquake in Greece in the 20th century. It was followed 13 minutes later by a magnitude 7.2 earthquake near Santorini. It triggered a major tsunami with a maximum run-up of 30 m. The combined effects of the earthquake shaking and the tsunami caused the deaths of 53 people with a further 100 injured.

The 1693 Sicily earthquake was a natural disaster that struck parts of southern Italy near Sicily, then a territory part of the Crown of Aragon by the Kings of Spain Calabria and Malta, on 11 January at around 21:00 local time. This earthquake was preceded by a damaging foreshock on 9 January. The main quake had an estimated magnitude of 7.4 on the moment magnitude scale, the most powerful in recorded Italian history, and a maximum intensity of XI (Extreme) on the Mercalli intensity scale, destroying at least 70 towns and cities, seriously affecting an area of 5,600 square kilometres (2,200 sq mi) and causing the death of about 60,000 people.

The earthquake was followed by a number of tsunamis that devastated the coastal villages on the Ionian Sea and in the Straits of Messina. Almost two-thirds of the entire population of Catania were killed. The epicentre of the disaster was probably close to the coast, possibly offshore, although the exact position remains unknown. The extent and level of destruction caused by the earthquake resulted in the extensive rebuilding of the towns and cities of southeastern Sicily, particularly the Val di Noto, in a homogeneous late Baroque style, described as "the culmination and final flowering of Baroque art in Europe".

Megathrust earthquakes occur at convergent plate boundaries, where one tectonic plate is forced underneath another. The earthquakes are caused by slip along the thrust fault that forms the contact between the two plates. These interplate earthquakes are the planet's most powerful, with moment magnitudes (M_w) that can exceed 9.0. Since 1900, all earthquakes of magnitude 9.0 or greater have been megathrust earthquakes.

The thrust faults responsible for megathrust earthquakes often lie at the bottom of oceanic trenches; in such cases, the earthquakes can abruptly displace the sea floor over a large area. As a result, megathrust earthquakes often generate tsunamis that are considerably more destructive than the earthquakes themselves. Teletsunamis can cross ocean basins to devastate areas far from the original earthquake.

A submarine, undersea, or underwater earthquake is an earthquake that occurs underwater at the bottom of a body of water, especially an ocean. They are the leading cause of tsunamis. The magnitude can be measured scientifically by the use of the moment magnitude scale and the intensity can be assigned using the Mercalli intensity scale.

Understanding plate tectonics helps to explain the cause of submarine earthquakes. The Earth's surface or lithosphere comprises tectonic plates which average approximately 80 km (50 mi) in thickness, and are continuously moving very slowly upon a bed of magma in the asthenosphere and inner mantle. The plates converge upon one another, and one subducts below the other, or, where there is only shear stress, move horizontally past each other (see transform plate boundary below). Little movements called fault creep are minor and not measurable. The plates meet with each other, and if rough spots cause the movement to stop at the edges, the motion of the plates continue. When the rough spots can no longer hold, the sudden release of the built-up motion releases, and the sudden movement under the sea floor causes a submarine earthquake. This area of slippage both horizontally and vertically is called the epicenter, and has the highest magnitude, and causes the greatest damage.

The 1950 Assam–Tibet earthquake, also known as the Assam earthquake, occurred on 15 August and had a moment magnitude of 8.7. The epicentre was located in the Mishmi Hills. It is one of the strongest earthquakes ever recorded on land.

Occurring on a Tuesday at 7:39 PM Indian Standard Time, the earthquake was destructive in both Assam (India) and Tibet (China), and approximately 4,800 people were killed. The earthquake is notable as being the largest recorded quake caused by continental collision rather than subduction, and is also notable for the loud noises produced by the quake and reported throughout the region.

The 1934 Nepal–India earthquake or 1934 Bihar–Nepal earthquake was one of the worst earthquakes in India's history. The towns of Munger and Muzaffarpur were completely destroyed. This 8.0 magnitude earthquake occurred on 15 January 1934 at around 2:13 pm IST (08:43 UTC) and caused widespread damage in northern Bihar and in Nepal.

The International Nuclear and Radiological Event Scale (INES) was introduced in 1990 by the International Atomic Energy Agency (IAEA) in order to enable prompt communication of safety and significant information in case of nuclear accidents.

The scale is intended to be logarithmic, similar to the moment magnitude scale that is used to describe the comparative magnitude of earthquakes. Each increasing level represents an accident approximately ten times as severe as the previous level. Compared to earthquakes, where the event intensity can be quantitatively evaluated, the level of severity of a human-made disaster, such as a nuclear accident, is more subject to interpretation. Because of this subjectivity, the INES level of an incident is assigned well after the occurrence. The scale is therefore intended to assist in disaster-aid deployment.