By Shabait,
An earthquake measuring 5.0 Richter scale was today witnessed in Asmara and Massawa cities at 12:04:23 PM local time.
Reports indicated that the tremor had its cores at the distances of 67 Km. north-east Asmara and 18 Km. north-west of Massawa port city, and that its depth was gauged as 10 Km.
Experts described the current incident as the one with greater intensity when compared with a similar experience registered in the year 2002 although no harm was reported. They further made remarks pertaining to the cautionary measures nationals should take in case of such instance.
In this connection, similar quakes reportedly occurred in Chile, Turkey, Argentina, Albania, Indonesia, Fox Islands, Aleutian Islands, Dominique, Southern Italy, Greece, Bolivia, Solomon Islands and Taiwan respectively.
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Earthquake of magnitude 5.0 in Eritrea, along the margin of the East African rift
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By Lorenzo Pasqualini,
An earthquake of magnitude 5.0 occurred at 11:53 Italian time in Eritrea, about 70 km north-east of the capital Asmara and 18 km from Massawa.
The estimated hypocentral depth is 9.8 km. The quake, which to what is the news from Africa has not resulted in damage to persons or property, occurred along the continental margin of the East African rift, the boundary between the African Plate and the Arabian. This is the point where the two plates move away from each other, due to the tectonic extensional. The process of rifting in the course, which is leading to the separation of the two plates, has already led to the formation of an ocean basin: the Red Sea.
The earthquake occurred today just off the coast of the Red Sea, and a few tens of km north of one of the most active volcanic areas in the world. band characterized by extensional tectonics is huge, extending from Turkey to Mozambique for about 6500 km. Its maximum width is recorded at the Red Sea, where it reaches 300 km. (Software Translation)
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Continental Breakup: M5.0, Eritrea
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By Jennifer Young,
Arguably the most interesting earthquake this week is the M5.0 which occurred in Eritrea. Geologically, this area is fascinating: A rising plume of rock sourced from deep within the earth is lifting the crust and will in time initiate continental breakup of Africa, with a new ocean forming between Ethiopia and Sudan.
The M5.0 of 18 September had its epicentre in Eritrea, north of the main hot spot.
This region is known as a triple junction, with ocean ridges along the axes of the Red Sea and Gulf of Aden already splitting Arabia from Africa and creating new ocean crust. The third arm, the East African Rift, propagates southwards to become the Great Rift Valley. With such dynamic processes in action, it’s unsurprising that this area is characterised by extensive volcanism and accompanied by earth tremors, although large earthquakes in the area are rare.
US Earthquakes: The Western States
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The majority of significant earthquake activity in the States this week continued to be in Alaska. Elsewhere there was no outstanding noteworthy event, but this in itself offers an opportunity to look at the overall pattern of tremors and to get some idea of the relationship between earthquakes and topography.
The San Andreas fault zone, a major plate boundary, is clearly dominant but other, older margins are equally important.
To understand the complex geological history of California, even at a very simple level, we need to understand that the US west of the Rockies is made up of various geological blocks which over time have ‘docked’ with continental North America. The boundaries of these blocks are structurally relatively weak – as is indicated by the broadly linear pattern of seismic activity. It’s also worth noting the scattering of tremors in and around Montana-Idaho-Wyoming, which results primarily from volcanic activity associated with the Yellowstone hot spot.
Creative Processes Cause Earthquakes
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The Eritrean earthquake, and its association with the Afar mantle plume, is exciting because it reminds us that earthquakes are not merely part of a destructive process – even though most major tremors are associated with subduction and melting of oceanic crust. The constructive processes by which new crust is created also involve enormous crustal forces and, as a result, are capable of generating noteworthy earthquakes.
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