The Modified Mercalli intensity scale measures the effects of an earthquake at a given location. This is in contrast with the seismic magnitude usually reported for an earthquake.
The 1811–1812 New Madrid earthquakes were a series of intense intraplate earthquakes beginning with an initial earthquake of moment magnitude 7.2–8.2 on December 16, 1811, followed by a moment magnitude 7.4 aftershock on the same day. Two additional earthquakes of similar magnitude followed in January and February 1812. They remain the most powerful earthquakes to hit the contiguous United States east of the Rocky Mountains in recorded history. The earthquakes, as well as the seismic zone of their occurrence, were named for the Mississippi River town of New Madrid, then part of the Louisiana Territory and now within the U.S. state of Missouri.
The 1983 Coalinga earthquake struck at 4:42 p.m. Monday, May 2 of that year, in Coalinga, California.
The Richter scale, also called the Richter magnitude scale, Richter's magnitude scale, and the Gutenberg–Richter scale, is a measure of the strength of earthquakes, developed by Charles Francis Richter and presented in his landmark 1935 paper, where he called it the "magnitude scale". This was later revised and renamed the local magnitude scale, denoted as ML or ML .
In the early morning hours of August 16, 1931, a powerful earthquake occurred in West Texas with a maximum Mercalli intensity of VIII (Severe). Estimates of its magnitude range between 5.8–6.4 mb, making it the most powerful earthquake ever recorded in Texas history. Its epicenter was near the town of Valentine, Texas; there, the earthquake caused damage to many homes and buildings. The earthquake may have been caused by movement along oblique-slip faulting in West Texas, the most seismically-active region in the state. Shaking from the earthquake was perceptible within a 400 mi (640 km) radius of the epicenter, affecting four U.S. states and northern Mexico. Several foreshocks and aftershocks accompanied the primary temblor, with the aftershocks continuing until at least November 3, 1931. The main earthquake caused no fatalities, though several people sustained minor injuries; the damage in Valentine amounted to $50,000–$75,000.
In seismology, an isoseismal map is used to show lines of equally felt seismic intensity, generally measured on the Modified Mercalli scale. Such maps help to identify earthquake epicenters, particularly where no instrumental records exist, such as for historical earthquakes. They also contain important information on ground conditions at particular locations, the underlying geology, radiation pattern of the seismic waves, and the response of different types of buildings. They form an important part of the macroseismic approach, i.e. that part of seismology dealing with noninstrumental data. The shape and size of the isoseismal regions can be used to help determine the magnitude, focal depth, and focal mechanism of an earthquake.
The 1867 Manhattan earthquake struck Riley County, Kansas, in the United States on April 24, 1867, at 20:22 UTC, or about 14:30 local time. The strongest earthquake to originate in the state, it measured 5.1 on a seismic scale that is based on an isoseismal map or the event's felt area. The earthquake's epicenter was near the town of Manhattan.
The 1916 Irondale earthquake struck in the north–central region of the U.S. state of Alabama on October 18. The strongest earthquake in state history, it registered an estimated Richter scale magnitude of 5.1 and resulted in minor damage. Damage was limited to Shelby and Jefferson counties and reached its maximum severity near the epicenter in the city of Irondale, including cracked windows, fallen chimneys, and dried-up wells. While there were no fatalities, the earthquake spawned widespread panic, prompting alarmed workers to evacuate tall buildings.
The 1920 Garfagnana earthquake occurred on 7 September in Garfagnana and Lunigiana, both agricultural areas in the Italian Tuscany region. The quake hypocenter was located 14 kilometres (8.7 mi) beneath Villa Collemandina. The maximum felt intensity was rated as X (Extreme) on the Mercalli intensity scale, and 6.6 on the Richter magnitude scale. It was one of the most destructive seismic events recorded in the Apenninic region in the twentieth century. Due to good news coverage, availability of official documents on the damage and abundance of recordings from surveillance stations throughout Europe, it was regarded as a first-rate case study to improve knowledge of tectonics and macroseismic analysis.
The 1925 Dali earthquake occurred at 14:42 UTC on 16 March. It had an estimated magnitude of 7.0 on the surface wave magnitude scale and a maximum perceived intensity of at least IX (Violent) on the Mercalli intensity scale. It had an epicenter in the province of Yunnan in southern China and killed an estimated 5,000 people.
Seismic intensity scales categorize the intensity or severity of ground shaking (quaking) at a given location, such as resulting from an earthquake. They are distinguished from seismic magnitude scales, which measure the magnitude or overall strength of an earthquake, which may, or perhaps may not, cause perceptible shaking.
A major seismic event occurred during the rule of the Qing dynasty in Shandong Province on July 25, 1668. The earthquake had an estimated magnitude of Ms 8.5, making it the largest historical earthquake in East China, and one of the largest to occur on land. The earthquake had cataclysmic implications to the region. An estimated 43,000 to 50,000 lives were lost in the earthquake, and its effects were widely felt. The epicenter may have been located between Ju County and Tancheng counties, northeast of the prefecture-level city of Linyi in southern Shandong.
The 1906 Manasi earthquake (玛纳斯地震), also known as the Manas earthquake occurred in the morning of December 23, 1906, at 02:21 UTC+8:00 local time or December 22, 18:21 UTC. It measured 8.0–8.3 on the moment magnitude scale and 8.3 on the surface-wave magnitude scale. The epicenter of this earthquake is located in Manas County, Xinjiang, China. An estimated 280–300 people died and another 1,000 more were injured by the earthquake.
The 2020 Kashgar earthquake, also known as the Jiashi earthquake occurred on 19 January 2020 at 21:27:56 China Standard Time in Xinjiang Province, China. According to the United States Geological Survey, the earthquake had a moment magnitude of 6.0 and a surface wave magnitude of 6.4 according to the China Earthquake Network Center. It struck at a shallow depth of 5.6 km according to the USGS while the CENC has the figure at 16 km. Local emergency management agencies said the earthquake damaged more than 1,000 homes and businesses in the nearby populated towns and villages. One person is known to have died while two other children were injured.
The 1900 Venezuelan earthquake, occurred on October 28 at between 4:30 and 4:45 am local time. This earthquake had an epicenter off Miranda State or near the Venezuelan capital Caracas, in the Cariaco Basin. It had an estimated moment magnitude of 7.6–7.7 and a surface-wave magnitude of 7.7–8.4. It had a maximum Mercalli intensity assigned VIII–X, causing landslides and liquefaction events. Many buildings were severely damaged or collapsed during the earthquake. It is thought to be the last great earthquake of the 19th century and the largest instrumentally recorded in the republic, having been felt throughout.
The 1995 Menglian earthquake or 1995 Myanmar–China earthquake occurred on 12 July at 05:46:43 local time in the Myanmar–China border region. The earthquake had an epicenter on the Myanmar side of the border, located in the mountainous region of Shan State. It registered 7.3 on the Chinese surface wave magnitude scale (Ms ) and 6.8 on the moment magnitude scale (Mw ). With a maximum Mercalli intensity assigned at VIII, the quake killed eleven people and left another 136 injured. Over 100,000 homes in both countries were destroyed and 42,000 seriously damaged. Some damage to structures were also reported in Chiang Mai and Chiang Rai, Thailand. The low death toll from this earthquake was attributed to an early warning issued prior to it happening. Precursor events including foreshocks and some seismic anomalies led to an evacuation of the area before the mainshock struck. It is thought to be one of the few successfully predicted earthquakes in history.
The 1954 Sofades earthquake struck central Greece on April 30, 1954 at 16:02 (UTC+3). It was estimated to be 6.7–7.0 Mw and had a maximum Modified Mercalli intensity of X (Extreme). More than 25 people died, 717 were injured and about 28,000 structures were damaged or destroyed.
The 1984 Cachar earthquake rattled much of Southern Assam on December 31, 1984, at 5:03 a.m. (UTC+5:30) with an epicenter 20 kilometers southwest of Lakhipur. The quake measured with a magnitude of 6.0 on the moment magnitude scale and an estimated intensity of VIII (Severe) on the Modified Mercalli intensity scale. About 20 people died and 100 others sustained mild to severe injuries.
The 1937 Heze earthquakes struck the Mudan District in Shandong Province, China on July 31 and August 1 respectively. The surface-wave magnitude 6.9 and 6.7 earthquakes were centered near the city of Heze. 3,252 people died, and 12,701 were injured, although the total number of casualties has never been finalized. The earthquakes also resulted in the loss of more than 6,000 livestock and destroyed 470,000 homes. Due to the outbreak of the Second Sino-Japanese War, rescue operations by the Chinese government were ineffective.
The 1983 Kaoiki earthquake struck southern Hawaii Island on the morning of November 16, 1983. Measuring Mw 6.7, it was the largest to hit the island since 1975. The epicenter was located 50 km southeast of Hilo with an approximated depth of 12 km. The shallow strike-slip earthquake was assigned a maximum intensity of IX (Violent) on the Modified Mercalli scale. 6 people were injured, widespread damage and landslides were reported across the island.
