Earthquakes are caused by movements within the Earth's crust and uppermost mantle. They range from events too weak to be detectable except by sensitive instrumentation, to sudden and violent events lasting many minutes which have caused some of the greatest disasters in human history. Below, earthquakes are listed by period, region or country, year, magnitude, cost, fatalities and number of scientific studies.
The 1938 Banda Sea earthquake occurred on February 2 with an estimated magnitude of 8.5–8.6 on the moment magnitude scale and a Rossi–Forel intensity of VII. This oblique-slip event generated destructive tsunamis of up to 1.5 metres in the Banda Sea region, but there were no deaths.
The International Seismological Centre (ISC) is a non-governmental, nonprofit organisation charged with the final collection, definitive analysis and publication of global seismicity. The ISC was formed in 1964 as an international organisation independent of national governments that would carry on the work of the International Seismological Summary in collecting and analyzing seismic data from around the world, and particularly to handle increased flow of data from the World-Wide Standard Seismograph Network (WWSSN), also established that year. The ISC considers its prime task to be the collection and re-analysis of all available earthquake seismic date in order to produce definitive data on earthquakes. The ISC's catalog is considered "the most complete and authoritative final depository of global earthquake parameter data."
This list of 20th-century earthquakes is a list of earthquakes of magnitude 6 and above that occurred in the 20th century. Sone smaller events which nevertheless had a significant impact are also included. After 1900 most earthquakes have some degree of instrumental records and this means that the locations and magnitudes are more reliable than for earlier events.
The 1971 Solomon Islands earthquakes occurred in the northern part of the Solomon Islands, within Papua New Guinea as a doublet earthquake. The first large shock occurred on July 14 at 06:11 UTC with a magnitude of 8.0. The second large event occurred on July 26 at 01:23 UTC with a magnitude of Mw 8.1. The initial event on July 14 caused a tsunami, which was observed in Rabaul. The earthquake of July 26 triggered a tsunami with a 3.4 m (11 ft) runup in New Britain.
The November 1960 Peru earthquake occurred offshore northern Peru on November 20 at . The magnitude of the earthquake was Ms 6.75 by using the conventional surface-wave magnitude measurement within a shorter duration of ~20 s. However, there is a large discrepancy between the magnitudes in Ms and Mw in this earthquake. The discrepancy was caused from the earthquake's long source duration of about 130 s, and by calculating the seismic moment, the magnitude would be Mw 7.6 or Mw 7.8, according to different sources. This earthquake belongs to a category of earthquakes with slow rupture velocities and potential of producing tsunamis larger than those expected from the moment magnitudes.
The 1941 Andaman Islands earthquake struck the Andaman Islands on June 26 with a magnitude of 7.7 to 8.1. Details of this event are poorly known as much of Southeast Asia was in the turmoil of World War II. The quake caused severe damage in the Andaman Islands. The tsunami it triggered was reported along the Andaman and Nicobar Islands, India and British Ceylon. There may have been damage and deaths in Bangladesh, Myanmar, and Thailand due to the tsunami.
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.
The Nemuro-Oki earthquake in scientific literature, occurred on June 17 at 12:55 local time. It struck with an epicenter just off the Nemuro Peninsula in northern Hokkaidō, Japan. It measured 7.8–7.9 on the moment magnitude scale (Mw ), 8.1 on the tsunami magnitude scale (Mt ) and 7.4 on the Japan Meteorological Agency magnitude scale (MJMA ).
On April 13, 1923 at 15:31 UTC, an earthquake occurred off the northern coast of the Kamchatka Peninsula in the USSR, present-day Russia. The earthquake had a surface-wave magnitude (Ms ) of 6.8–7.3 and an estimated moment magnitude (Mw ) of 7.0–8.2. This event came just two months after a slightly larger earthquake with an epicenter struck south of the April event. Both earthquakes were tsunamigenic although the latter generated wave heights far exceeding that of the one in February. After two foreshocks of "moderate force", the main event caused considerable damage. Most of the 36 casualties were the result of the tsunami inundation rather than the earthquake.
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.
United States, Kodiak Island, Alaska (Magnitude 7.9) October 9
Venezuela, Miranda (state) (Magnitude 7.7) October 29 25 deaths
