Sciency Thoughts: Samos

Showing posts with label Samos. Show all posts

Friday, 2 September 2022

Magnitude 5.2 Earthquake to the northwest of the island of Samos.

The Geodynamics Institute of the National Observatory of Athens recorded a Magnitude 5.2 Earthquake at a depth of 12.8 km, beneath the Aegean Sea, about 15 km to the northwest of the island of Samos, at about 1.10 pm local time (about 11.10 am GMT) on Wednesday 31 August 2022. No damage or injuries have been reported following this event, but people have reported feeling the event across much of the Aegean region, the eastern Greek mainland, and western Anatolia.

The approximate location of the 31 August 2022 Samos Earthquake. USGS.

The Aegean Sea is underlain by the Aegean Sea Plate, a small tectonic plate caught between the African Plate to the south, the Anatolian Plate to the east and the Eurasian Plate to the northwest. The Anatolian Plate is being pushed to the west by the northward movement of the Arabian Plate to the east, pushing the Aegean Plate south and west into collision with the northward moving African Plate. Part of the African Plate is being subducted beneath the Aegean Plate along the Hellenic Trench, which runs to the south of the Greek Islands from Cyprus to Crete then northwest under the Ionian sea parallel to the Peloponnesian Coast. This is not a smooth process, as the plates frequently stick together then break apart once the pressure has built up sufficiently, leading to (fairly frequent) Earthquakes.

Simplified map of the plate movements of the eastern Mediterranean. Univeriteit Utrecht.

Friday, 30 October 2020

Nineteen confirmed deaths after Earthquake between the Greek island of Samos and the Izmir Peninisula, Turkey.

The United States Geological Survey recorded a Magnitude 7.0 Earthquake at a depth of 21.0 km, about 15 km to the north of the island of Samos and a similar distance to the south of the Izmir Peninsula, slightly after 2.50 pm in Turkey and slightly after 1.50 pm in Greece (slightly after 11.50 pm GMT) on Friday 30 October. The Earthquake causes several buildings to collapse in the Turkish city of Izmir, where seventeen deaths and 703 injuries have been confirmed so far. Two fatalities have been confirmed on Samos, a pair of teenagers struck by a collapsing wall, and several islands in the area were hit by a tsunami wave, causing damage to properties.

The approximate location of the 30 October 2020 Samos Earthquake. USGS.

The are where the Earthquake occurred lies on the boundary between the Anatolian Plate, to the north, the Aegean Sea Plate (underlying the Peloponnese, Attica, The Cyclades Islands, Crete, the Dodecanese Islands and Turkey to the southeast of the Taurus Mountains) to the west and the African Plate to the south. Northern Greece and the north coast of Turkey lie on the Eurasian Plate. Both countries are highly prone to earthquakes because of this.

Rescue workers attempting to free people from a collapsed building in Izmir, Turkey, following an Earthquake on 30 October 2020. EPA.

To the east the Arabian Plate is being pushed north and west by the movement of the African Plate, further to the south. This leads to a zone of tectonic activity within the province, as the Arabian and Anatolian plates are pushed together, along the East Anatolian Fault, and past one-another, along the Dead Sea Transform.

Simplified map of the plate movements of the eastern Mediterranean. Univeriteit Utrecht.

This movement also leads to a zone of faulting along the northern part of Turkey, the North Anatolian Fault Zone, as the Anatolian Plate is pushed past the Eurasian Plate, which underlies the Black Sea and Crimean Peninsula (transform faulting). This is not a simple process, as the two plates constantly stick together, then break apart as the pressure builds up, leading to Earthquakes, which can be some distance from the actual fault zone.

Collapsed buildings in the Turkish city of Izmir following a Magnitude 7.00 Earthquake on 30 October 2020. CNN.

Witness accounts of Earthquakes can help geologists to understand these events, and the structures that cause them. The international non-profit organisation Earthquake Report is interested in hearing from people who may have felt this event; if you felt this quake then you can report it to Earthquake Report here.

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Thursday, 16 August 2012

A giant Monitor Lizard from the Miocene of Samos, Greece.

Monitor Lizards, Varanidae, are carnivorous Lizards noted for their large size and aggressive behavior. While the majority of the group are not exceptionally large, the largest members are bigger than any other Lizards. The extant Komodo Dragon reaches 3 m in length, and the extinct Giant Australian Monitor is thought to have reached lengths of around 7 m. Among the Squamates (the group that includes Snakes and Lizards) only the Boas, Pythons and extinct Mosasaurs (a group of fully marine Reptiles that went extinct at the end of the Cretaceous) are larger, and among Lizards the only species that reach comparable sizes are the limbless Amphisbaena and Glass Snakes. More remarkably still, the Monitor Lizards appear to have repeatedly evolved large forms in places where they were in direct competition with carnivorous Mammals; the Boas and Pythons, in contrast, evolved large sizes before the evolution of large Mammals, and have simply remained large.

In a paper published in the journal PLoS One on 10 August 2012, Jack Conrad of the Anatomy Department at the New York College of Osteopathic Medicine, and the Department of Vertebrate Paleontology at the American Museum of Natural History and Ana Balcarcel and Carl Mehling, also of the Department of Vertebrate Paleontology at the American Museum of Natural History, describe a new species of Monitor Lizard from the Miocene of Samos, Greece.

The new specimen was collected by the famous palaeontologist Barnum Brown (discoverer of Tyrannosaurus rex, amongst other things) in the 1920s, and have lain undescribed in the collection of the American Museum of Natural History ever since. It was found in the Turolian (Late Miocene) Mytilini Formation of northern Samos, making it 6.9–7.6 million years old.

Map of Greece with Samos enlarged. Circle indicates the locality where the Monitor fossil was found. The star indicates Athens. Conrad et al. (2012).

The new species is placed in the extant Monitor Lizard genus Varanus, and given the specific name amnhophilis, meaning 'lover of lamb', in reference to the tendency of large monitors to take Mammalian prey. The remains from which it is reconstructed are extremely fragmentary, but it is thought that it would have been about 70 cm in length, making it the earliest known large member of the genus Varanus.

Reconstructions of Varanus amnhophilis, based upon the available material. (Top) Complete animal. (Bottom) Head. Conrad et al. (2012).