Twenty two confirmed deaths as Cyclone Ockhi sweeps across the Lakshadweep Archiapelago.

Twenty two people have been confirmed dead after Cyclone Ockhi swept across the Lakshadweep Archipelago, part of the Indian State of Kerala, on Saturday 2 December 2017. The majority of the deaths occurred in the islands' coastal communities and fishing fleet, which has been scattered by the storm, with over 500 fishermen rescued by vessels from the Indian Navy. Coastal communities and fishing vessels from the Keralan mainland have also been badly hit, as have those in Tamil Nadu and Sri Lanka, where at least seven people have died.

Storm damage in Kanyakumari District, Tamil Nadu following the passage of Cyclone Ockhi. European Commission/Flickr.

Tropical storms are caused by solar energy heating the air above the oceans, which causes the air to rise leading to an inrush of air. If this happens over a large enough area the inrushing air will start to circulate, as the rotation of the Earth causes the winds closer to the equator to move eastwards compared to those further away (the Coriolis Effect). This leads to tropical storms rotating clockwise in the southern hemisphere and anticlockwise in the northern hemisphere.These storms tend to grow in strength as they move across the ocean and lose it as they pass over land (this is not completely true: many tropical storms peter out without reaching land due to wider atmospheric patterns), since the land tends to absorb solar energy while the sea reflects it.

 The passage of Cyclone Winston till 07.00 GMT on Tuesday 28 March 2017  (thick line) with its predicted future path (thin line, circles represent the margin of error on the predictions). Colours indicate the strength of the storm. Tropical Storm Risk.

The low pressure above tropical storms causes water to rise there by ~1 cm for every millibar drop in pressure, leading to a storm surge that can overwhelm low-lying coastal areas, while at the same time the heat leads to high levels of evaporation from the sea - and subsequently high levels of rainfall. This can cause additional flooding on land, as well as landslides, which are 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.

 Storm damage in Colombo, Sri Lanka, following the passage of Cyclone Ockhi. Lakruwan Wanniarachchi/AFP.

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Magnitude 1.1 Earthquake near Dumfries, Scotland.

The British Geological Survey recorded a Magnitude 1.1 Earthquake at a depth of about 2 km roughly 10 km to the north of the town of Dumfries in Dumfries and Galloway, Scotland, slightly after 0.30 am GMT on Thursday 28 November 2017. This was not a major event, and presented no threat to human life or property, but may have been felt locally.

The approximate location of the 28 November 2017 Dumfries Earthquake. Google Maps.

Earthquakes become more common as you travel north and west in Great Britain, with the west coast of Scotland being the most quake-prone part of the island and the northwest of Wales being more prone  to quakes than the rest of Wales or most of England.

The precise cause of Earthquakes in 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. 

(Top) Simplified diagram showing principle of glacial rebound. Wikipedia. (Bottom) Map showing the rate of glacial rebound in various parts of the UK. Note that some parts of England and Wales show negative values, these areas are being pushed down slightly by uplift in Scotland, as the entire landmass is quite rigid and acts a bit like a see-saw. Climate North East.

 

Witness accounts of Earthquakes can help geologists to understand these events, and the structures that cause them. If you felt this quake, or were in the area but did not (which is also useful information) then you can report it to the British Geological Survey here.  

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Lactura rubritegula: A new species of Tropical Burnet Moth from Texas.

Tropical Burnet Moths, Lacturidae, are found in tropical and subtropical areas across the world, with their maximum diversity in the Indo-Australian regions. They are small-to-medium sized Moths with wingspans of 11-65 mm, and tend to be cream in colour with orange, red and yellow patterns. Their larvae are leaf skeletonisers, and tend to be brightly coloured. Seventeen species are known from North and Central America, though all of these are rather similar in general appearance, with grey forewings with rows of red or black spots, and uniformly pink-red hindwings, and individuals being variable within this general pattern, making it difficult to identify these Moths to species level.

In a paper published in the journal ZooKeys on 23 October 2017, Tanner Matson and David Wagner of the Department of Ecology and Evolutionary Biology at the University of Connecticut, describe a new species of Tropical Burnet Moth from southern Texas.

The new species is placed in the genus Lactura and given the specific name rubritegula, meaning 'red tegula', where the tegula is the section of carapace above and before the wing of an Insect (roughly the 'shoulder'). The species is easily distinguished by this red area. The males of the species have wingspans of 9.5 to 10.5 mm, the females are slightly larger at 10.0-12.0 mm, but otherwise similar with salmon-red bodies and cream wings.

Lactura rubritegula, male specimen. Matson & Wagner (2017).

Larvae of this species are greenish with red stripes and yellow spots, and are found on the leaves of the Gum Bully bush, Sideroxylon lanuginosum, with flying adults observed in April and May and larvae taking a year to mature. The species was discovered in Hill County in southern Texas, and a single specimen was also found in Harris County, however the Gum Bully bush is widely distributed in the southern United States and Mexico, and it is possible that this Moth has a similar distribution and has previously been overlooked.

Larvae of Lactura rubritegula. Matson & Wagner (2017).

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British tourist attacked by Crocodile at Cape Tribulation in northern Queensland.

A 24-year-old woman believed to be a British tourist was attacked by a Saltwater Crocodile, Crocodylus porosus, at Cape Tribulation in northern Queensland, Australia, on Wednesday 27 November 2017. The attack happened at about 6.00 om local time, when the Crocodile launched itself suddenly from a creek, and left the woman with a series of puncture wounds in her upper thigh. She received treatment at Mossman Hospital, and is not thought to be in a serious condition. 

Injuries sustained by a British woman in a Crocodile attack on 27 November 2017 (inset) and the area where the attack took place (main picture). Cairns Post/Facebook.

A two meter Saltwater Crocodile was later captured at the beach by the Department of Environment and Heritage Protection and will be offered for rehoming to a local zoo or wildlife park (Saltwater Crocodiles are protected in Queensland and killing one carries stiff penalties). The incident comes roughly eighteen months after another woman, Cindy Waldron, from New South Wales, was killed by a Crocodile while wading in the sea near Cape Tribulation, and has led to calls for a cull of the animals by some local politicians.

The approximate location of the 27 November 2017 Cape Tribulation Crocodile attack. Google Maps.

Saltwater Crocodiles are one of the few Crocodile species not considered vulnerable to extinction, being found from India to Australia  and inhabiting many areas that Humans shun, such as Mangrove forests and islands without fresh water. However they are protected in Queensland and other Australian states where they are present, as they are considered an important part of local aquatic ecosystems, and were hunted almost to extinction there between the 1940s and 1960s. They are large animals, reaching about seven meters in length, and are ambush predators capable of taking large prey, including, on occasion, Humans. This can lead to problems as they recolonise areas where they were previously exterminated and encounter Humans who are naïve to their habits, or areas where tourism provides a regular supply of Crocodile-unwary people.

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