Magnitude 5.4 Earthquake in North Gyeongsang Province, South Korea.

The United States Geological Survey reported a Magnitude 5.4 Earthquake at a depth of 10.0 km about 10 km northwest of the city of Pohang in North Gyeongsang Province, South Korea, slightly before 2.30 pm, local time (slightly before 5.30 am GMT) on Wednesday 15 November 2017. The quake caused extensive damage to buildings in and around Pohang, with over a thousand buildings destroyed or damaged and more than 1500 people made homeless and 57 reported injuries, with ten people hospitalised and two described as being in critical conditions. People have reported feeling the event across South Korea, and it is likely that it was also felt in North Korea. The event was followed by at least 45 aftershocks.

Damage in Pohang, South Korea, following the 15 November 2017 Earthquake. Min Kyung-suck/Newsis/AP.

Korea lies on the southern part of the Amurian Plate, a breakaway section of the Eurasian Plate that also underlies parts of China, Japan, and the Russian Far East. The border with the Eurasian Plate lies to the east of the Korean Peninsula; this is a divergent margin along which new seafloor is being created, pushing the Eurasian and Amurian Plates apart. The Amurian Plate is also moving south relative to the Eurasian Plate, creating extra stresses along the margin between the two plates. Despite this significant Earthquakes in South Korea are not common events, and this is the second largest ever recorded there.

 Map of Plate Framework in the Northeast Asia. Study area is depicted by open red box. Boundaries of the Okhotsk (OK) and Amur (AM) plates are shown. Surrounding plates include Eurasia (EU), North America (NA), Pacific (PA), Philippine Sea (PS), and Yangtze (YA). Black vectors give model velocities (with numbers in mm/a) relative to plate whose identifier is underlined. Black circles are locations of Euler poles. Akira Takeuchi (2013).

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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Hippocampus haema: A new species of Seahorse from Japan and Korea.

Seahorses, Hippocampus spp., are small marine Bony Fish related to Pipefish, from which group they appear to have diverged during the Miocene, distinguished by having Horse-like heads, an upright posture, bony armour divided into segmented rings, prehensile tails, and the internal brooding off eggs by the males. They are found in shallow temperate and tropical seas around the world, favouring Seagrass beds, Mangrove forests, Coral reefs, and estuaries. The taxonomy of Seahorses is difficult, as the group is very morphologically conservative, with ichthyologists using traditional methods having suggested as few as two species, while modern genetic methods suggest there are probably more than fifty. Understanding Seahorse taxonomy is important, as many populations are threatened by Human activities, including habitat destruction, and collecting for use as food, traditional medicine, souvenirs and in aquariums, and it is difficult to establish proper conservation measures without knowing how what species individual populations belong to.

In a paper published in the journal ZooKeys on 31 October 2017, Sang-Yun Han and Jin-Koo Kim of the Department of Marine Biology at Pukyong National University, Yoshiaki Kai of the Maizuru Fisheries Research Station of Kyoto University, and Hiroshi Senou of the Kanagawa Prefectural Museum of Natural History, describe a new species of Seahorse from Japan and Korea, described as part of a review of the Seahorse species found in these nations.

The new species is named Hippocampus haema, where 'haema' is the Korean word for 'Seahorse'. It has 10 body segments plus 35-38 tail segments, double gill-openings and a high, backwards-swept crown, and is highly variable on colour, with observed individuals being black, white, orange, yellow, magenta, claret, brown, or grey with black, red, or white stripes. The smallest sexually mature male specimen found measures 59.3 mm in length, the largest specimen found measured 100.3 mm. The species was found along the southern and southeastern coasts of the Korean Peninsula, the western coast of Kyushu and northwestern coast of Honshu, in floating Sargassum and weeds on shallow soft bottom habitats, at depths of up to 18 m.

Hippocampus haema, (A) colouration of fresh specimen, (B) X-radiograph; a' indicates the anterior coronet spine; 5' indicates the posterior coronet spine (the 5th tip on the corona); the first (1) and last (10 or 11) trunk rings are marked. Han et al. (2017).

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