Monday, 25 September 2017

Over a thousand people displaced by flooding in Cross River State, Nigeria.

Flooding has displaced over a thousand people in Cross River State, as heavy rains since 18 September 2017 have led to homes and farmland being inundated with water. The communities of Bago, Unu, Bagabo, Bakie, Bufua, and Kakwe-Beebo are reported to have been worst hit, by flooding that has washed away houses, crops, and bridges and contaminated clean drinking water sources.

Bridge destroyed by flooding at Bebuo Bomaji in Cross Rivers State, Nigeria. The Guardian Nigeria.

West Africa has a distinct two season climatic cycle, with a cool dry season during the northern winter when prevalent winds blow from the Sahara to the northeast, and a warm rainy season during the northern summer when prevalent winds blow from the Atlantic Ocean to the southwest. These warm winds from the Atlantic are laden with moisture, which can be lost rapidly when the air encounters cooler conditions, such as when it is pushed up to higher altitudes by the Jos Plateau of central Nigeria and Shebshi Mountains on the border with Cameroon.

 Rainfall and prevalent winds during the West African dry and rainy seasons. Encyclopedia Britanica.
Cross Rivers has a Tropical Climate with distinct dry and rainy seasons. The rainy season lasts from May to October, with September typically being the wettest month. Like other areas of West Africa, Nigeria has suffered a series of flooding and related incidents this rainy season, driven by high temperatures over the Atlantic Ocean.

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83-year-old man dies after being caught in a landslide in Penang State, Malaysia.

An 83-year-old man has died after being caught in a landslide in Penang State, Malaysia, on Friday 15 September 2017. Liew Ah Kiew, of Jalan Buah Jambu, narrowly escaped from the incident, which destroyed his home, suffering injuries to the neck in the process. He died in hospital on Thursday 21 September of heart failure.

The funeral of Mr Liew Ah Kiew, who died after being caught in a landslide in Penang State, Malaysia. The Star.

The incident happened after weeks of heavy rainfall in the area; landslides are a common problem after severe weather events, as excess pore water pressure can overcome cohesion in soil and sediments, allowing them to flow like liquids. Malaysia has become increasingly landslip-prone in recent years due to extensive deforestation, which leaves soil exposed to heavy tropical rainfall. 

Landslide in Tanjung Bungah, Georgetown, Penang State, earlier this month. The Star.

Penang has suffered a series of weather-related incidents this month, including the worst flooding in fifteen years and a series of landslides. The state has a wet tropical climate with two distinct rainy seasons (common close to the equator, where the Sun is highest overhead around the equinoxes and lowest on the horizons around the solstices). These run from April to May and September to November, with peak rains in September and October.

 Flooding in Penang State, Malaysia, earlier this month. Shahnaz Fazlie Shahrizal/New Straits Times.

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Sunday, 24 September 2017

Thousands evacuated from area around Mount Agung, Bali, after rise in seismic activity.

Around 34 000 people have been evacuated from the area within 9 km Mount Agung in eastern Bali, following a sharp rise in seismic activity beneath the mountain. Seismic activity beneath volcanoes can be significant, as they are often caused by the arrival of fresh magma, which may indicate that a volcano is about to undergo an eruptive episode. Mount Agung last erupted in 1963-4, when it produced ash columns reaching 10 km above its 3 km high summit and lava flows that reached 7 km from the volcano, as well as triggering a series of lahars and pyroclastic flows that killed over 200 people, making people on the island very cautious about any future eruptions.

Mount Agung on Bali, Indonesia. Travel Wires.

The Indo-Australian Plate, which underlies the Indian Ocean to the south of Java, Bali and Lombok, is being subducted beneath the Sunda Plate, a breakaway part of the Eurasian Plate which underlies the islands and neighbouring Sumatra, along the Sunda Trench, passing under the islands, where friction between the two plates can cause Earthquakes. As the Indo-Australian Plate sinks further into the Earth it is partially melted and some of the melted material rises through the overlying Sunda Plate as magma, fuelling the volcanoes of Java and neighbouring islands.

Subduction along the Sunda Trench beneath Java, Bali and Lombok. Earth Observatory of Singapore.

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Pegylis majori: A new species of Scarab Beetle from the Hamer Region of Ethiopia.

Scarab Beetles, Scarabeidae, are a large and diverse group, containing about 30 000 known species from around the world. These Beetles are typically large and robust, and often with a metallic colouration. Many Scarab Beetles are excellent diggers, and many of these digging Scarabs share a habit of burying their eggs with a supply of dung to feed their young, gaining them the name Dung Beetles, though others lay their eggs on carrion, decaying plant matter, or in some cases living plants. Members of the genus Pegylis are found across tropical Africa and have larvae which feed on the roots of plants.

In a paper published in the journal Zootaxa on 22 September 2017, Richard Sehnal of the Department of Zoology and Fisheries, at the Czech University of Life Sciences Prague, describes a new species of Pegylis from the Hamer Reion of Ethiopia.

The new species is named Pegylis majori, in honour of Vladimír Major, who collected the specimens from which the species is described. The species is described from eleven male and four female specimens, all collected from near the town of Turmi in the Hamer Region, at an altitude of about 950 m. The males range from 14.4 to 16.3 mm in length, the females from 18.0 to 18.5 mm, both sexes being a metallic black colour, given a russet hue by the presence of many small orange hairs. 

Pegylis majori, (A) male, and (B) female, both in dorsal view. Sehnal (2017).

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Magnitude 1.9 Earthquake off the southwest coast of Jersey.

The British Geological Survey recorded a Magnitude 1.9 Earthquake at a depth of 6 km, roughly 15 km to the southwest of the island of Jersey in the Channel Islands slightly before 0.20 am British Summertime (slightly before 1.20 am GMT) on Friday 22 September 2017. Although large for the area, the quake was still to small to present any threat to human activity, and there were no reports of any damage or injuries relating to this event.
The approximate location of the 22 September 2017 Jersey Earthquake. Google Maps.
The precise cause of Earthquakes around the UK can be hard to determine; the country is not close to any obvious single cause of such activity such as a plate margin, but is subject to tectonic pressures from several different sources, with most quakes probably being the result of the interplay between these forces.
Britain is being pushed to the east by the expansion of the Atlantic Ocean and to the north by the impact of Africa into Europe from the south. It is also affected by lesser areas of tectonic spreading beneath the North Sea, Rhine Valley and Bay of Biscay. Finally the country is subject to glacial rebound; until about 10 000 years ago much of the north of the country was covered by a thick layer of glacial ice (this is believed to have been thickest on the west coast of Scotland), pushing the rocks of the British lithosphere down into the underlying mantle. This ice is now gone, and the rocks are springing (slowly) back into their original position, causing the occasional Earthquake in the process. 
 Simplified diagram showing principle of glacial rebound. Wikipedia.
Glacial rebound seems an unlikely cause of Earthquakes beneath the Channel Islands, an area that was never glaciated, but this is not entirely the case. The northwest of Scotland is rising up faster than any other part of the UK, but the Earth's crust onland in the UK is fairly thick, and does not bend particularly freely, whereas the crust beneath the Channel is comparatively thin and more inclined to bend under stress. Thus uplift in Scotland can cause the entire landmass of Great Britain to pivot, causing movement in the rocks beneath the Channel.
 Map showing areas of the British Isles currently rising or sinking as a result of glacial rebound. Wikipedia.
Witness accounts of Earthquakes can be useful to geologists trying to understand the processes that cause them and the rocks beneath the surface. If you felt this quake (or if you were in the area but did not feel the quake, which is also useful information) then you can report it to the British Geological Survey here.
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Saturday, 23 September 2017

Blindness in wild Kiwi.

Birds are considered to have the best vision in any living Vertebrate group, with almost all Birds having large eyes relative to their size and densely packed retinal neurons, along with other specialisations found in different species and groups. This is closely tied to the ecology of Birds, which typically fly, are visual foragers and rely on markings and display to find mates. However, one group of Birds, the flightless Kiwi, Apteryx spp., of New Zealand, appear to break with this pattern, having small eyes relative to their size, under-developed visual regions of the brain and the smallest visual field of any Birds. Kiwi also have a very different feeding ecology to other Birds, being nocturnal foragers on the floor of canopy forests, with highly developed senses of smell hearing and touch, particularly at the tip of the long bill, which has a unique set of mechanoreceptors (touch neurons), raising questions as to how much value vision is to a Kiwi at all.

In a paper published in the journal BMC Biology on 12 September 2017, Bret Moore of the William R. Pritchard Veterinary Medical Teaching Hospital at the University of California-Davis, Joanne Paul-Murphy of the Department of Medicine and Epidemiology, also at the University of California-Davis, Alan Tennyson of the Museum of New Zealand Te Papa Tongarewa, Christopher Murphy of the Department of Surgical and Radiological Sciences at the University of California-Davis, and the Department of Ophthalmology & Vision Science at the University of California-Davis, describe the incidence of widespread visual impairment, including blindness, in a population of wild Okarito Brown Kiwi, Apteryx rowi.

An Okarito Brown Kiwi, Apteryx rowi, on Mana Island, New Zealand, in June 2017. Leon Berard/New Zealand Birds Online.

Out of a population of 160 Kiwi examined, 53 were found to have some form of visual impairment, and four were completely blind. The Birds were found to suffer from a variety of conditions, including corneal opacification and shrunken fibrotic globes. Many of these infections appeared chronic in nature, suggesting that they were long-term conditions that had not had any undue impact on the Bird’s overall health. This included three of the completely blind specimens, which appeared healthy at the time of inspection, and which were shown by radio-tagging to survive for at least four years after the initial inspection, with one of these Kiwi going on to form a pair-bond with a visually healthy individual. 

Normal and pathologic findings for the anterior segment of the Okarito Brown Kiwi. Complete ophthalmic examinations consisted of slit lamp biomicroscopy, direct ophthalmoscopy, and streak retinoscopy. Lack of vision was interpreted by no response to light or motion, combined with the severity of ocular lesions (e.g. inability to visualize intraocular structures beyond the abnormal ocular tissue, such as marked corneal or lens opacification). (a) Normal anterior segment. Note the small palpebral aperture (mean diameter 8.53 ± 0.50 mm SD, n = 9 birds). (b) Nuclear sclerosis: a normal aging change in the lens associated with changes in lens protein composition. Nuclear sclerosis generally has minimal visual consequences in animals. (c) Buphthalmia with marked corneal edema. This animal was blind bilaterally but was in good physical condition. (d) Phthisis bulbi (a globe shrunken with fibrosis). Potential causes include any chronic inflammatory or glaucomatous process or severe trauma. (e), (f) Resorbing, end-stage cataracts. (g) Anteriorly luxated cataract. h Inferiorly luxated cataract. Moore et al. (2017).

From this Moore et al. conclude that the loss of vision has no real impact on Kiwi. They suggest that while the Birds may use vision to determine the difference between night and day, useful for determining when to forage, but do not appear to need working vision to obtain food (indeed they cannot see the tips of their beaks, their principle foraging tool), nor to obtain a mate. They suggest that Kiwi may be in the process of losing their vision by regressive evolution, i.e. vision is no longer being selected for, so the visual abilities of the Birds are slowly degenerating as deleterious mutations build up in the DNA regions which govern vision.

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Landslide kills two in Cebu City. The Philippines.

Two people have been killed and several more have been evacuated after a landslide hit the community of Sitio Lower Ponce in the Capitol Site area of Cebu City, on the Philippine island of the same name. The dead have been named as Elpedio Geraga, 64, and Juvelyn Sanipa, 31. The incident happened at about 8.15 pm on Thursday 21 September 2017, after about five hours of continuous heavy rain. Landslides are a common problem after severe weather events, as excess pore water pressure can overcome cohesion in soil and sediments, allowing them to flow like liquids.Approximately 90% of all landslides are caused by heavy rainfall. Cebu has a wet and dry tropical climate, with a long rainy season that lasts from May to January. 

 Rescue workers at the site of the 21 September 2017 Cebu landslide. Junjie Mendoza/Cebu Daily News.

Cebu has a tropical climate with distinct wet and dry seasons. The wet season lasts from June to October and brings with it frequent heavy rains and associated problems. The community of Sitio Lower Ponce is an informal settlement (i.e. built without formal permission or adherence to planning rules by members of a poor community) on a 45 degree slope above a road. This site is home to several hundred people, and is prone not just to landslides, but also to floods and fires.

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