Mercalli intensity scale in the context of "1693 Sicily earthquake"

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 1169 Sicily earthquake occurred on 4 February 1169 at 08:00 local time on the eve of the feast of St. Agatha of Sicily (in southern Italy). It had an estimated magnitude of between 6.4 and 7.3 and an estimated maximum perceived intensity of X (Extreme) on the Mercalli intensity scale. The cities of Catania, Lentini and Modica were severely damaged, and the earthquake also triggered a paleotsunami. Overall, the earthquake is estimated to have caused the deaths of at least 15,000 people.

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 1976 Tangshan earthquake (Chinese: 唐山大地震; pinyin: Tángshān dà dìzhèn; lit. 'Great Tangshan earthquake') was a M_w 7.6 earthquake that hit the region around Tangshan, Hebei, China, at 19:42:55 UTC on 27 July (03:42:55, 28 July local time). The maximum intensity of the earthquake was XI (Extreme) on the Mercalli scale. In minutes, 85 percent of the buildings in Tangshan collapsed or were rendered unusable, all services failed, and most of the highway and railway bridges collapsed or were seriously damaged. The official count stated 242,469 deaths, while historians accepted at least 300,000 died, making it the deadliest earthquake in recorded history (excluding the famine deaths from the 1556 Shanxi earthquake) and one of the worst disasters in China by death toll.

The 1906 San Francisco earthquake was a major earthquake which struck the coast of Northern California at 05:12 am Pacific Standard Time on Wednesday, April 18, 1906. With an estimated moment magnitude of 7.9 and a maximum Mercalli intensity of XI (Extreme), it created high-intensity shaking from Eureka on the North Coast to the Salinas Valley, an agricultural region to the south of the San Francisco Bay Area.

Devastating fires soon broke out in San Francisco and lasted for several days. More than 3,000 people died and over 80% of the city was destroyed. The event is remembered as the deadliest earthquake in the history of the United States. The death toll remains the greatest loss of life from a natural disaster in California's history and high on the list of worst American disasters.

In seismology, strong ground motion is the strong earthquake shaking that occurs close to (less than about 50 km from) a causative fault. The strength of the shaking involved in strong ground motion usually overwhelms a seismometer, forcing the use of accelerographs (or strong ground motion accelerometers) for recording. The science of strong ground motion also deals with the variations of fault rupture, both in total displacement, energy released, and rupture velocity.

As seismic instruments (and accelerometers in particular) become more common, it becomes necessary to correlate expected damage with instrument-readings. The old Modified Mercalli intensity scale (MM), a relic of the pre-instrument days, remains useful in the sense that each intensity-level provides an observable difference in seismic damage.

The 1918 Celebes Sea earthquake occurred on August 15 at 12:18 UTC near the Moro Gulf coast of Mindanao. It had a magnitude of 8.3 on the moment magnitude scale and a maximum perceived intensity of X (Extreme) on the Mercalli intensity scale, making it the strongest earthquake in history to hit the Philippines. It triggered a tsunami of up to 7 m in height and the combined effects of the earthquake and tsunami led to the deaths of 52 people.