Rukwa Trough, Tanzania magnitude 4.7 earthquake (8:49 AM, 15 October 2021) : 無料・フリー素材/写真
Rukwa Trough, Tanzania magnitude 4.7 earthquake (8:49 AM, 15 October 2021) / James St. John
| ライセンス | クリエイティブ・コモンズ 表示 2.1 |
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| 説明 | This is a seismogram from the Kilima Mbogo seismic station in Kenya. The prominent red noise on the 05:30 line (click on the image once or twice to zoom in) represents shock waves from a magnitude 4.7 earthquake that hit southwestern Tanzania in eastern Africa. The quake occurred at 8:49 AM, local time, on 15 October 2021. The epicenter was about 10.5 kilometers south-southeast of the town of Kaoze, Tanzania.This earthquake occurred in the Rukwa Trough, a branch of the East African Rift Valley. Eastern Africa is being ripped apart by the Afar Hotspot. Two rift branches radiating from the hotspot are so deep that they've been flooded by the oceans - the Red Sea and the Gulf of Aden. The East African Rift Valley is a third rift branch - it extends ~southward into Africa. In places, the rift valley is deep enough to host lakes. In the far future, it will also be flooded by seawater. Earthquakes occur throughout the rift system. Active and potentially active volcanoes are also present.The magnitude 4.7 Tanzania quake took place at the southern margin of the Rukwa Trough, south of Lake Rukwa. It appears to have occurred from a jolt of movement along the Ufipa Fault, a major normal fault that separates the Rukwa Trough from the Ufipa Plateau.See info. at:earthquake.usgs.gov/earthquakes/eventpage/us6000fute/exec...anden.wikipedia.org/wiki/East_African_Rift--------------------------------An earthquake is a natural shaking or vibrating of the Earth caused by sudden fault movement and a rapid release of energy. Earthquake activity is called "seismicity". The study of earthquakes is called "seismology". The actual underground location of an earthquake is the hypocenter, or focus. The site at the Earth's surface, directly above the hypocenter, is the epicenter. Minor earthquakes may occur before a major event - such small quakes are called foreshocks. Minor to major quakes after a major event are aftershocks.Most earthquakes occur at or near tectonic plate boundaries, such as subduction zones, mid-ocean ridges, collision zones, and transform plate boundaries. They also occur at hotspots - large subsurface mantle plumes (Examples: Hawaii, Yellowstone, Iceland, Afar).Earthquakes generate four types of shock waves: P-waves, S-waves, Love waves, and Rayleigh waves. P-waves and S-waves are body waves - they travel through solid rocks. Love waves and Rayleigh waves travel only at the surface - they are surface waves. P-waves are push-pull waves that travel quickly and cause little damage. S-waves are up-and-down waves (like flicking a rope) that travel slowly and cause significant damage. Love waves are side-to-side surface waves, like a slithering snake. Rayleigh waves are rotational surface waves, somewhat like ripples from tossing a pebble into a pond.Earthquakes are associated with many specific hazards, such as ground shaking, ground rupturing, subsidence (sinking), uplift (rising), tsunamis, landslides, fires, and liquefaction.Some famous major earthquakes in history include: Shensi, China in 1556; Lisbon, Portugal in 1755; New Madrid, Missouri in 1811-1812; San Francisco, California in 1906; Anchorage, Alaska in 1964; and Loma Prieta, California in 1989. |
| 撮影日 | 2021-10-15 12:49:51 |
| 撮影者 | James St. John |
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