Landslides at limestone quarries kill at least 74 in the Philippines.

Landslides at two limestone quarries have killed at least 74 people in the Philippines this week. At Itogon in Benguet Province on Luzon Island the bodies of 45 people have been recovered and 57 more are missing after a landslide struck an accomodation block where people were sheltering from Typhoon Mangkhut (referred to as Typhoon Ompong in the Philippines) on Saturday 15 September 2018. Despite the large number of people still missing, rescue operations have had to be severly cut back following warnings that the site was still unstable by the Mines and Geosciences Bureau, who raised concenrs that the low probability of finding any further survivors were outweighed by the high probability of further landslips at the site, endangering the lives of rescue workers.

Rescue workers remove a body from the scene of a landslide at a limestone quarry at Itogon in Beguet Province, the Philippines, on Tuesday 18 September 2018. Ted Aljibe/AFP.

At Naga on Cebu Island a second landslide, again associated with a limestone quarry, struck two villages on Thursday 20 September, burrying over 20 homes. Twenty nine bodies have now been recovered following this incident, and it is feared that more than fifty further victims could be burried beneath the rubble. 

Rescue workers at the scene of a landside at Naga on Cebu Island, the Philippines, earlier this week. Bullit Marquez/Associated Press.

Both incidents have been linked to heavy rains associated with Typhoon Mangkhut. 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. These events have prompted the Philippine Government to halt mining operations across a large area of the country while safety checks are carried out.

Tropical storms are caused by the warming effect of the Sun over tropical seas. As the air warms it expands, causing a drop in air pressure, and rises, causing air from outside the area to rush in to replace it. If this happens over a sufficiently wide area then the inrushing winds will be affected by centrifugal forces caused by the Earth's rotation (the Coriolis effect). This means that winds will be deflected clockwise in the northern hemisphere and anti-clockwise in the southern hemisphere, eventually creating a large, rotating Tropical Storm. They have different names in different parts of the world, with those in the northwest Pacific being referred to as typhoons.

 Typhoon Mangkhut imaged by the Japan Meteorological Agency’s Himawari-8 satellite on 14 September 2018. /Cooperative Institute for Research in the Atmosphere/Regional and Mesoscale Meteorology Branch/Colorado State University/Wikimedia Commons.

Despite the obvious danger of winds of this speed, which can physically blow people, and other large objects, away as well as damaging buildings and uprooting trees, the real danger from these storms comes from the flooding they bring. Each drop millibar drop in air-pressure leads to an approximate 1 cm rise in sea level, with big tropical storms capable of causing a storm surge of several meters. This is always accompanied by heavy rainfall, since warm air over the ocean leads to evaporation of sea water, which is then carried with the storm. These combined often lead to catastrophic flooding in areas hit by tropical storms.

Typhoon Mangkhut is considered to be the most severe tropical storm of 2018, and is attributed with the deaths of 81 people in the Philippines, not counting those at the Naga quarry or any unknown deaths at the Itogon quarry, as well as four in Guangdong Province, China and one in Taiwan. It also caused extensive damage in Maccau and Hong Kong,  where over 240 people were injured, but no fatalities have been reported. 

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Österplana 065: A unique meteorite from the Middle Ordovician of Sweden.

Ordinary chondrites, or stony meteorites, are the most abundant group of meteorites falling on Earth today, forming about 85% of all such objects. They are divided into three subgroups, based upon their mineralogy and chemical composition, H (42% of the total), L (47% of the total) and LL (11% of the total), which are thought to be derived from three different parent bodies, asteroids broken up by some ancient collision or other event. The advent of isotopic dating methods has enabled scientists to calculate the ages of these meteorites, with type H and LL chondrites all being older than 3.5 billion years (i.e. older than these methods can effectively date, and probably dating from close to the origin of the Solar System, but type L chondrites have proved to be much younger, dating from about 470 million years ago, the Middle Ordovician on Earth. Interestingly this coincides with a great increase in the number of meteorites and micrometeorites falling to Earth, as recorded in marine sediments from the time, an increase which has been linked to the Great Ordovician Biodiversification Event, a sudden increase in the turnover and evolution of many marine invertebrate groups, which led to the replacement of many dominant invertebrate groups from the Cambrian with others more typical of the later Palaeozoic. 

In a paper published in the journal Nature Communications on 14 June 2016, Birger Schmitz of the Astrogeobiology Laboratory at Lund University and the Hawai’i Institute of Geophysics and Planetology at University of Hawai’i at Manoa, Qing-zhu Yin and Matthew Sanborn of the Department of Earth and Planetary Sciences at the University of California at Davis, Mario Tassinari, also of the Astrogeobiology Laboratory at Lund University and Caroline Caplan and Gary Huss, also of the Hawai’i Institute of Geophysics and Planetology at University of Hawai’i at Manoa, describe a unique meteorite from the Middle Ordovician limestone deposits of Thorsberg Quarry in southern Sweden.

Micrometeorites, which have very low masses and are very numerous, are fairly common in the rock record, but larger meteorites are very rare, and when found are often badly deformed by their impact and later geological movements, and in addition often have most or all of their minerals replaced, (as in biological fossils). The limestone deposits at Thorsberg Quarry are remarkable in that they preserve a large number of meteors that fell into a shallow sea with a seafloor covered by soft lime clays, which are preserved without any deformation. As with other ancient meteorites, most of the original minerals have been replaced, however some spinels and other minerals have been preserved, allowing some analysis of the meteors. To date over a hundred meteors from Thorsberg Quarry have been studied, all of which have been L type ordinary chondrites.
 

The new meteorite described by Schmitz et al., Österplana 065, does not conform mineralogicaly or chemically with an L type chondrite, or any other previously described meteor type. It appears to lack any of the type of chromite mineral grains which are common in ordinary chondrites, nor does it have any aluminium spinels, the most common type in L chondrites, having a mixture of chromium spinels and chromium-titanium spinels. Furthermore no silicate minerals could be found within the new meteorite, but large rutile grains could; this combination of chromium spinels plus rutile is not known from any of the approximatwly 52 600 meteorites examined and classified by scientists to date.

The Österplana 065 fossil meteorite from the Glaskarten 3 bed. The meteorite is 8 × 6.5 × 2 cm large. It is surrounded by a grey reduction halo, in the otherwise red limestone. Oxygen was consumed when the meteorite weathered on the sea floor. The coin in the image has a diameter of 2.5 cm. Schmitz et al. (2016).

While Österplana 065 is mineralogically different to the type L chondrites it was found alongside, it does share one other feature with them. Cosmic-ray exposure age dating is a method used to date meteorites, by studying nuclides (atoms of a specific isotope of an element) produced by cosmic rays striking minerals on the surface of the rock. Since a rock burried within the centre of an asteroid will not be exposed to cosmic rays, the amount of such nuclides can be used to estimate the time that such a rock has been exposed to space, presumably by the break-up of a larger body. All of the Thorsberg Quarry meteorites, including Österplana 065, yielded cosmic-ray exposure ages of less than a million years, suggesting that they had been released from inside a larger body by a collision less than a million years before falling to Earth and being buried again. Schmitz et al. suggest that this could imply Österplana 065 is a relict of the body which collided the parent body of the L type chondrites, in the collision that resulted in the formation of those bodies, a body of which we have to date discovered no other traces.

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Sinkhole opens up at Kansas golf course.

Part of the fairway at the Canyon Farms Golf Course in Lenexa, Kansas has had to be closed after a large sinkhole opened up on the course on Friday 19 June 2015. Nobody was injured by the event, however the hole, which is about 3 m deep, presents a major obstacle to golfers, and it is not clear at the current time what can be done to repair the course.

Aerial photograph of the Canyon Farms Golf Course sinkhole. KCTV5.

Sinkholes are generally caused by water eroding soft limestone or unconsolidated deposits from beneath, causing a hole that works its way upwards and eventually opening spectacularly at the surface. Where there are unconsolidated deposits at the surface they can infill from the sides, apparently swallowing objects at the surface, including people, without trace. Potash, a potassium salt, is readily soluble and can be dissolved quickly if water gains access to deposits, leading to the rapid formation of sinkholes.

The approximate location of the Canyon Farms Golf Course sinkhole. Google Maps.

The Canyon Farms Golf Course is known to have been partially constructed over an old limestone mine, and this appears to have been the cause of the sinkhole. It is likely that heavy rain in the past weeks has led both to water-logging of surface sediments (increasing their weight) and weakening of buried limestone deposits from which extraction previously occurred. Rainfall can be acidified by carbon dioxide, which dissolves in the water to form carbonic acid, which presents no immediate health threat to humans but which attacks limestone vigorously. 

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Police vehicle swallowed by sinkhole in Sheridan, Colorado.

A Sheridan Police Department SUV was swallowed by a sinkhole that opened up beneath it unexpectedly at about 2.15 am local time on Friday 5 June 2015. The single occupant of the vehicle, police sergeant Greg Miller, was able to craw out of the hole, which was...

Giant sinkholes appear at Missouri golf course.

A pair of giant sinkholes have appeared at the Top of the Rock Golf Course in Taney County, Missouri, on Friday 22 May 2014. The larger of the two sinkholes measures 25 m across by 10 m deep, while the...

US Marine killed by Missouri Sinkhole.

A US Marine has died after falling into a 20 m sinkhole while hunting deer in near Buckthorn in Pulaski County, Missouri, on the evening of Monday 16 September 2013. It is thought that the sinkhole opened up in...

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A Late Jurassic lagerstätte from central Poland

The term lagerstätte is used by Palaeontologists to describe a particularly rich fossil source; a site where fossils are either exceptionally numerous or exceptionally well preserved (or, ideally, both). One of the best known of these is the Solnhofen Limestone, or Solnhofen Plattenkalk, which formed in the early Tithonian,  towards the end of the Jurassic, as a result of intense global warming that covered most of what is now Southern Germany with a shallow tropical sea. This was populated by abundant reef-forming Sponges and Corals, leading to the formation of numerous lagoons, in which the waters became cut of from the surrounding sea, then became hyper-saline due to evaporation.

In a paper published in the journal Lethaia in January 2013, Adrian Kin of the Institute of Geological Sciences at Jagiellonian University, Michał Gruszczyński of the Institute of Geography at Jan Kochanowski University, David Martill of the School of Earth & Environmental Sciences at the University of Portsmouth, Jim Marshall of the School of Environmental Sciences at the University of Liverpool and Błażej Błażejowski of the Institute of Paleobiology at the Polish Academy of Sciences, describe a newly discovered fossil lagerstätte from the Owadów-Brzezinki Quarry in central Poland, thought to be of late Tithonian origin, slightly younger than the Solnhofen Limestone.

The Owadów-Brzezinki Lagerstätte comprises three distinct units with a total thickness of about 13m. The lowermost unit (Unit I) comprises yellowish marly limestones grading upwards into massive fine-grained limestones and is roughly 6.6 m thick This unit contains numerous Zaraiskites Ammonites. The second unit (Unit II) comprises thinnly bedded, fine-grained limestones with occasional distinctive parallel lamination. Zaraiskites is also present in this unit, though less numerous, whch also contains a single thin horizon with a mass occurrence of Polychaete Worm tubes (serpulite). The uppermost unit (Unit III) comprises fine grained limestones with a variety of bedding structures. Zaraiskites is rare here, but the bed contains a wide variety of other fossils, notably the bivalve Corbulomima obscura as well as avariety of other marine invertebrates, including Bivalves, Brachiopods, Arthropods, Fish, Sharks, Sphenodonts and  (non-marine) Insects and Pterosaurs.

The quarry at Owadów-Brzezinki showing the successive sedimentary units I–III of the studied Late Tithonian (= Middle Volgian) strata. In the right column are details of the studied profile: (1) thick-bedded limestones of unit I; (2) thin-bedded limestones of unit II; (3) lithographic- type limestones of unit III; (4) boundaries dividing units; (5) serpulite; (6) Corbulomima horizon; (7) tsunamite or mega-stormite. Kin et al. (2013).

The sequence is thought to represent a progression from a shallow marine offshore environment to a nearshore environment, possibly coastal or lagoonal. Unit I appears to have formed bellow the storm wave base where sediments were heavily bioturbated by marine organisms, while Unit three shows signs of being influenced by numerous weather events, as well as horizons of tidal and evaporitic origin, suggesting that the waters were becoming shallower throughout the succession. The beds are believed to have been laid down in a shallow epicontinental (inland) sea which dominated central Europe during the Late Jurassic. The unit also contains a bed considered to be tsunamigenic in origin, which Kin et al. suggest may be related to Earthquake activity on the nearby Middle Polish Trough, an area of active subduction in the Late Jurassic.

Palaeogeographical map showing position of the Owado´w-Brzezinki quarry on the margin of the Middle Polish Trough. Kin et al. (2013).

The vast majority of fossils from the location come from a single bed within Unit III, referred to as the Corbulomima horizon, due to the presence of large numbers of the bivalve Corbulomima obscura. In addition to the bivalves his unit produces Ostracods, Ammonites, Brachiopods, Limulids (Horseshoe Crabs), Dragonflies, Beetles, Sharks, Boney Fishes, Sphenodonts (Squamate Reptiles related to Snakes and Lizards), Pterosaurs and a variety of other fossils.

Fossils from the Corbulomima horizon of Unit III. (A) Nearly complete exuvia of the Horseshoe Crab Crenatolimulus sp.. (B) Fragmentary preserved pycodontid fish skeleton (possibly tuberculate scales of Coelodus sp.). (C) Wing of the dragonfly Eumorbaeschna sp.. (D) Partial skeleton of indeterminate pycnodontid fish preserved in situ. Scale bars are all 10 mm. Kin et al. (2013).

Fossils from the Corbulomima horizon. (A) Bivalves:  

Mesosaccella sp. (1) and numerous representatives of Corbulomima  

obscura (2). (B) Indeterminate pterosaur tooth. (C) The only example  

of Zaraiskites zaraiskensis found from the Corbulomima  

horizon.  

Kin et al. (2013).

Examples of vertebrates from the Corbulomima horizon. (A) mandible of aquatic Sphenodontian Pleurosaurus goldfussi. (B) Nearly 

complete dentary bone of Actinopterygian (Ray-finned) Fish Caturus sp.. (C) Details of same specimen, showing teeth of the mid dentary in detail. Scale

bars are all 10 mm.

Kin et al. (2013).

See also A new species of Split-foot Lacewing from the Middle Jurassic of Inner Mongolia, Opportunistic Bivalves during the Early Jurassic Toarcian Oceanic Anoxic Event, A Caddisfly from the Middle Jurassic of Inner Mongolia, Choristopsychid Insects from the Middle Jurassic of Inner Mongolia and A Pliosaur from the Jurassic Coast of Dorset.

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Landslide at limestone quarry kills six in Omdurman, Sudan.

Six people have been killed ad another five injured in a landslide at a quarry in Omdurman (Umm Durman) in Khartoum State, Sudan on Tuesday 8 October 2013. It is understood that the quarry was artisanal in nature, with people excavating limestone on a small scale for their own needs as a building material rather than being managed by a governing corporation. Most landslides are the result of excess rainfall, as excess pore water pressure can overcome cohesion in soil and sediments, allowing them to flow like liquids, however on this occasion it is not thought to have been a factor. Local authorities had apparently previously determined that the site was becoming unstable due to unplanned excavation of rock, and had advised against further quarrying at the site.

The approximate location of the 8 October 2013 Omdurman quarry landslide. Google Maps.

Omdurman is the largest city in Sudan, lying on the west bank of the Nile, opposite the capitol, Khartoum, on the east. The quarrying of limestone and granite is an ancient industry here, local quarries having supplied the monuments of ancient Nubia, and to some extent Egypt.

See also At least fifteen dead following landslide in Freetown, Sierra Leone, Four year old boy killed by landslide in Bududa District, eastern Uganda, Two workers killed in landslide at Bihar quarry, Three workers killed in landslide at Mumbai quarry and Three workers killed in rockfall at Thai limestone quarry.

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Three workers killed in landslide at Mumbai quarry.

Three workers have been killed, and a further two injured, in a landslide at a quarry in Navi Mumbai (a satelite town of Mumbai), in Maharashtra State, India. The incident happened at the Turbe Sainath Patil Quarry at arround 10.30 am local time (around 5.00 am, GMT) on Tuesday 18 June 2013, while the five men were operating drilling equipment at the site, following days of heavy rains associated with the onset of the Monsoon Season. Local police have reportedly arrested the director of opporetions at the site, Manan Shaikh, on suspision of causing the deaths by negligence; local press report that this is not the first incident at the quarry.

 Rescue workers using a crane to clear debris at the site of the Navi Mumbai landslide. Outlook India.

 The three men who died have been named as Polus Fansing Topoo (18), Lal Fansing Topoo (22) and Musku Surin (25) all migrant labourers hailing from Jharkhand State. The two injured men were Bhujal Kassap (23) and Ramesh Topu (25), also from Jharkhand.

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.

See also Seven killed in Nepal landslide, Three workers killed in rockfall at Thai limestone quarry, Fifteen-year-old boy killed in Kathmandu landslide, Seven people killed by Landslide in Shaanxi Province, China and Three people killed by landslide in Sichuan Province, China,

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Three workers killed in rockfall at Thai limestone quarry.

Three workers are known to have died following the collapse of a rockwall at a Thai quarry on Monday 3 June 2013, and another four are trapped beneath the rubble. The incident happened at the Phetsamut Quarry in Khao Yoi Disterict, roughly 110 km southwest of Bangkok. The rockfall is reported to have occurred after heavy rains associated with the onset of Thailand's monsoon season. The workers at the quarry are a mixture of Thai and Myanmar nationals. Some reports are putting the death toll as high as six.

Collapsed rocks at the Phetsamut Quarry in Khoa Yoi District. 3 June 2013. MCOT.

Thailand has undergone a major construction boom in recent years, fueling demand for limestone both as a building material in its own right and as the main ingredient in cement. Limestone is a common rock and relatively easy both to locate and extract, but doing this safely is slightly harder. Limestone deposits are often interbedded with softer sedimentary rocks such as clays. When these are exposed to precipitation they can be extremely absorbent, but as water is absorbed they lose cohesion and can be washed out, undermining the more resilient limestone layers and leading to rockfalls.

The approximate location of the Phetsamut Quarry. Google Maps.

See also Seven people killed in Mexican landslide, Seven people killed by Landslide in Shaanxi Province, China, One child dead and another missing following Minnesota landslide, US professor killed in Nepal landslide and Three people killed by landslide in Sichuan Province, China.

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