The Modified Mercalli intensity scale, developed from Giuseppe Mercalli's Mercalli intensity scale of 1902, is a seismic intensity scale used for measuring the intensity of shaking produced by an earthquake. It measures the effects of an earthquake at a given location, distinguished from the earthquake's inherent force or strength as measured by seismic magnitude scales. While shaking is caused by the seismic energy released by an earthquake, earthquakes differ in how much of their energy is radiated as seismic waves. Deeper earthquakes also have less interaction with the surface, and their energy is spread out across a larger volume. Shaking intensity is localized, generally diminishing with distance from the earthquake's epicenter, but can be amplified in sedimentary basins and certain kinds of unconsolidated soils.
The 2006 Mendoza earthquake was a medium-intensity seismic movement in the province of Mendoza, Argentina. It took place at 11:03 AM (UTC-3) on 5 August 2006, and had a magnitude of 5.6 in the Richter scale. Its hypocenter was centered 23 km west southwest of San Martin, exactly at the town of Ugarteche, Luján de Cuyo, and at a depth of 25 km.
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The 1921 Massawa earthquake took place off the coast of Massawa, Eritrea, on August 14 with a moment magnitude of 6.1 and a Mercalli intensity of VIII (Severe). The first aftershock after the initial earthquake was of similar magnitude. Significant damage was caused to the harbour at Massawa with a number of deaths reported. Aftershocks were felt as far away as Asmara and Dekemhare.
The 1915 Asmara earthquake took place outside Asmara, Eritrea on September 23 with an Mw of 6.2 and a maximum perceived intensity of VI (Strong) on the Mercalli intensity scale.
The 2007 Aysén Fjord earthquakes occurred in Aisén Fjord, Chile from January 22 – April 22. The biggest occurred at 1:53 p.m. on April 21 and reached a felt intensity of VII on the Mercalli intensity scale. On the moment magnitude scale, the earthquake reached a magnitude of 6.2. Ten people disappeared due to a tsunami caused by a landslide, according to ONEMI, but three bodies were found on April 22 by the Chilean Navy.
The 2007 Alum Rock earthquake occurred on in Alum Rock Park in San Jose, in the U.S. state of California. It measured 5.6 on the moment magnitude scale and had a maximum Mercalli intensity of VI (Strong). The event was then the largest in the San Francisco Bay Area since the 1989 Loma Prieta earthquake, which measured 6.9 on the moment magnitude scale, but was later surpassed by the 2014 South Napa earthquake. Ground shaking from the Alum Rock quake reached San Francisco and Oakland and other points further north. Sixty thousand felt reports existed far beyond Santa Rosa, as far north as Eugene, Oregon.
The 1925 Charlevoix–Kamouraska earthquake struck northeastern North America on February 28, reaching 6.2 on the moment magnitude scale. It was one of the most powerful measured in Canada in the 20th century, with a maximum perceived intensity of VIII (Severe) on the Mercalli intensity scale at its epicentre in the area of Charlevoix-Kamouraska along the Saint Lawrence River near île aux Lièvres and not greater than VI (Strong) in the United States. The quake was felt in Quebec City, Shawinigan, Montreal, as far south as Virginia, and as far west as the Mississippi River.
The 1926 Kars/Leninakan earthquake occurred at 21:59 local time on 22 October 1926 in the border area of Soviet Armenia and eastern Turkey. It had a surface wave magnitude of 6.0 and a maximum felt intensity of IX (Violent) on the Mercalli intensity scale, causing 360 casualties. Many buildings in Leninakan and surrounding villages were destroyed or damaged.
The 1985 Rapel Lake earthquake occurred on 8 April at with a moment magnitude of 7.5 and a maximum perceived intensity of VI (Strong). The shock was centered 75 kilometres (47 mi) southwest of Santiago, Chile, with a focal depth of 37.8 km (23 mi).
The 1872 North Cascades earthquake occurred at in central Washington Territory. A maximum Mercalli intensity of VIII (Severe) was assessed for several locations, though less intense shaking was observed at many other locations in Washington, Oregon, and British Columbia. Some of these intermediate outlying areas reported V (Moderate) to VII shaking, but intensities as high as IV (Light) were reported as far distant as Idaho and Montana. Due to the remote location of the mainshock and a series of strong aftershocks, damage to structures was limited to a few cabins close to the areas of the highest intensity.
A magnitude 6.9 earthquake struck Myanmar 135 km (84 mi) north-west of Mandalay on April 13 with a maximum Mercalli intensity of VI (Strong). It struck at 8:25 pm local time, and was centered in an isolated area. The estimated depth was 134 km. It lasted for around one minute according to Xinhua reporters.
A magnitude 6.8 earthquake struck Myanmar 25 km (16 mi) west of Chauk on 24 August 2016 with a maximum Mercalli intensity of VI (Strong). It struck at 5:04 pm local time, and was centered in an isolated area. The estimated depth was 84.1 km. Tremors from the earthquake were felt in Yangon, in the eastern cities of Patna, Guwahati, and Kolkata in India, in Bangkok in Thailand and in Dhaka, the capital of Bangladesh. According to reports, several temples in the nearby ancient city of Bagan were damaged and four people were reported dead.
The 1934 Hansel Valley earthquake occurred on March 12 at approximately 8:05 a.m. MST with a moment magnitude of 6.6 and a maximum Mercalli intensity of VIII (Severe). The shock originated in the Hansel Valley at the north end of the Great Salt Lake in Utah in the United States. Damage was mostly confined to vulnerable buildings, and two people died. The dip-slip (normal) fault that generated the shock ruptured the surface of the ground and other geologic features were documented. A large aftershock occurred three hours after the initial event and may have caused additional damage.
The 1901 Richfield earthquake was a magnitude 7.0 earthquake that occurred on 13 November 1901 at approximately 9:39 PM MDT at Richfield, Utah, United States. If estimations are accurate, it is the largest earthquake ever recorded in Utah.
An earthquake struck near the Hawaiian island of Lanai on February 19, at 10:11 pm HST with an estimated magnitude of 7.5 on the moment magnitude scale (Mw ). It remains one of the largest seismic event to hit the Hawaiian Islands since the 1868 Ka‘ū earthquake, with its effects being felt throughout the entire archipelago. It caused severe damage on the islands of Lanai, Molokai and Maui. A tsunami may have been generated however there are speculations if it had actually happened. Despite the size of the quake and the extent of damage, there were no deaths.
The 1870 Charlevoix earthquake occurred on 20 October in the Canadian province of Quebec. It had a moment magnitude of 6.6 Mw and a Modified Mercalli intensity rating of X (Extreme). The town of Baie-Saint-Paul was seriously damaged by the event, with the loss of six lives. Effects from the earthquake were felt as far as Virginia and along the New England coast of the United States.
A moment magnitude 7.5–7.6 earthquake struck offshore near the Tanimbar Islands, Maluku, Indonesia, at a depth of 105.1 km, on 10 January 2023.
