I wrote these four essays in the mid-90s for an encyclopedia published in America in the twentieth century. I offer the translation of the English text as an example of the methodology for the analysis of catastrophic events, practiced with the aim to draw conclusions for the future.
EARTHQUAKE IN ARMENIA
brief summary. About 25,000 people have died in an earthquake of magnitude 6.9 that caused the collapse of many buildings in three jerry-built towns and 150 villages in northern Armenia. The event
. The main shock occurred at 11.41 on 7 December 1988, about 80 km south of the main chain of the Caucasus. The shaking lasted 30 seconds and reached 21% gravitational accelerator. Four minutes later came a aftershocks of magnitude 5.9, which caused further collapse of the buildings already damaged by the first knocked.
Officially, 24,944 people died, although some estimates were much higher. Of the 31,000 wounded, the hospital had 12,200.
Circa il 40% del territorio armeno fu interessato dal terremoto, e, dei 150 paesi danneggiati, 58 villaggi furono quasi interamente distrutti e 3 città furono gravemente danneggiate: Leninakan (pop. 290.000), Spitak (pop. 20.000) e Kirovakan (pop. non conosciuta). Ben 8 milioni di metri quadri degli alloggi (il 17% del totale armeno) furono distrutti o resi inagibili. Soltanto a Leninakan, 72 edifici alti sono crollati e 60 altri sono stati danneggiati oltre qualsiasi possibilità di ricupero. A Spitak, 9 km dall'epicentro, nessun alloggio rimase utilizzabile. In tutta la zona interessata dal sisma i senzatetto furono 514.000.
Mentre, i due impianti termonucleari dell'Armenia non ricevettero danni (un colpo di fortuna, dato la loro mancanza di adeguati sistemi di sicurezza), 130 fabbriche furono danneggiate o distrutte, un duro colpo all'economia armena. Le perdite economiche ammontavano a US$15 miliardi.
Le frane sismiche erano numerosissime, come erano i fenomeni di liquefazione. Alcuni villaggi molto isolati furono colpiti da valanghe detritiche, causando perdite di vite, e diverse strade e linee di ferrovia interrotte dai movimenti franosi. Come in altri eventi sismici di impatto molto disperso, i soccorsi raggiunsero i villaggi più remoti soltanto con massiccio ritardo.
Il comportamento sismico degli edifici . La cattiva qualità del suolo sotto Kirovakan, Leninakan e Spitak causò il crollo di diversi edifici, ma the type and quality of construction they recorded much more. The older buildings were built of stone, often of a volcanic rock that broke during the seismic shaking. These buildings were very heavy horizontal elements of mattoneria or concrete, and then the dynamic load of the earthquake caused the crack angle to cause the collapse to the outside walls and the free fall of internal plans. However, many older buildings made of stone have withstood the earthquake, and most buildings had collapsed less than 15 years.
The more modern buildings were of reinforced concrete, often with preformed panels are also made of concrete. But the weakness of the joints in the frames Structural often leads to the progressive and total collapse of the building. If not, the scales fell off and collapsed during the seismic shaking, thus preventing the evacuation of occupants.
altisismiche standards in Armenia was insufficient in that it underestimated the probability of strong shaking and because they were based on an insufficient amount of data. However, while the quake was not likely in itself, the seismicity of the area was well known, such as to indicate the appropriate measures to be taken. But the Armenian authorities had ignored a fundamental scientific work of 1975, which clarified the need for earthquake resistant construction.
The epidemiology of infortuni . Dal terremoto di Guatemala del 1976, a quello di Armenia del 1988, si è imparato molto sugli infortuni causati dagli eventi sismici, specialmente in rapporto alle inefficienze delle operazioni di soccorso, l'inutilità dei materiali inviati nella zona disastrata, e la predominanza di ferite da schiacciamento dovute al crollo degli edifici scossi dal sisma.
Mentre alcune vittime morirono di asfissia a causa della polvere proveniente dagli edifici sgretolati dai tremori, molti sono morti schiacciati sotto travi e macerie. La "sindrome dello schiaccamento" avviene quando la proteina mioglobulina viene rilasciata in quantità massiccia nel flusso del sangue dalla rottura del tessuto muscolare. Essa finisce per impedire il funzionamento the kidneys, requiring immediate dialysis to save the life of the patient. Similar phenomena occur when potassium is released into the blood stream from the crushed cell disruption. In Yerevan, the kidney dialysis unit sent by the United States allowed the execution of 25-35 daily dialysis.
A sample of three Armenian villages, a total of 8,500 residents, showed a mortality of 49.5%, and a traumatic morbidity of 14.6%. But apart from the city level, the worst took place in some unusual buildings that collapsed with a mortality rate of over 90% of the occupants. Thus 205 of 215 workers died in a factory, and 285 of 302 children in a school. Typically, the plates constituent plans of such buildings disintegrated into fragments so small as not to give space to survive in the rubble.
Under the rubble lay about 40,000 people, of whom only 15,000 have been pulled out alive, most other survivors using only rudimentary tools. While some victim was rescued less than 19 days after the earthquake, 90% and saved lives of people trapped were freed within 24 hours after the main shock.
Logistics . The operations of search and rescue and relief efforts in general, were chaotic, inefficient and slow to begin. The weather alternated between snow fog, with night temperatures going down to-20EC. In fact, the situation weather, coupled with the fact that almost all hospitals in the area affected by the earthquake were not working anymore, slowing down relief efforts in particular. In addition, 80% of doctors and nurses in the area died in the earthquake. Then, the wounded had to be taken to Yerevan and Tbilisi. The lack of an adequate system of air traffic management, along with bad weather, had resulted in two aerial combat, with a total of 85 dead.
The problem of drugs. In the early days of the disaster are missed analgesics, antibiotics, anesthetics, intravenous fluids, syringes, stretchers, and equipment to transport the wounded.
Approximately 60 hours after the strike began rescue operation in which as many as 70 nations donavano money, manpower, food and other aid. Within a week after the disaster, the main airport in Yerevan operated 150 flights per day and 32 stores of donated material. Over 5,000 tonnes of medicines and medical supplies have arrived from abroad (25-30% by value of all donations), of which only 30% result, while 8% had expired and 11% were type useless. Most of the rest consisted of a total of 238 medicinal names in 21 different languages, making it impossible to identify the substance in question. The translations were rare in Russian and in Armenian non-existent. So at the end of the month you had to destroy 20% of medicines. In addition, a strategy efficiente per gestire i rifornimenti medici si è avuta soltanto 2 settimane dopo il disastro. Nel frattempo i produttori di medicinali hanno apparentemente colto l'occasione per scaricare i loro avanzi sulla zona disastrata.
Il contesto . Il terremoto armeno avvenne in mezzo ad un processo di trasformazione dell'Unione Sovietica. Fu il primo evento del genere in cui le autorità sovietiche accettarono una grande quantità di auiti dall'estero.
Tuttavia, la gravità del disastro non riuscì a cancellare le preesistenti preoccupazioni politiche: alcuni soccorritori azeri sono stati aggrediti dagli armeni, alcuni politici locali usavano la situazione per diffondere l'ultranazionalismo, le tensioni etniche grew strongly, and finally even the coprifuovo and the presence of 13,000 Soviet troops managed to contain the situation.
FIRE IN MEDITERRANEAN CALIFORNIA
brief summary. In the autumn of 1993 some spot fires in southern California burned 79,000 acres and 1,814 homes, especially in Malibu. Three people died in the flames. The event
. At the end of October 1993, a series of fires burned a large section of the Mediterranean's southern and most urbanized of the State of California. In six counties, including Los Angeles, 14 fire completely destroyed 731 houses and 66,800 hectares of heathland. Economic losses were estimated at more than $ 1 billion.
beginning of November 1993 nine other fires have killed three people, injured 111 and destroyed 1,084 homes, leaving more than 30,000 people homeless. In Malibu, 350 houses were destroyed, with damage amounting to $ 375 million. The injuries complained of smoke poisoning, burns and lung damage caused by breathing superheated air.
The Malibu fire began east of the city at 11.45 on November 2, 1993. In 4 hours, the flames traveled 19 km along the deep valleys carved into the coastal hills until it reaches the Pacific Ocean. The fire leapt in the air and 15-20 m beachfront palm trees burst spectacularly into flames.
Gusts a kind of Santa Ana wind threw hot and dry air at 90 mph and pushed the fire towards the urban area of \u200b\u200bthe coast, necessitating the evacuation of schools, factories, homes and a university. Many residents, worried about the fate of their homes, refused to evacuate. Therefore, rather than to fight the flames, firefighters in the middle of a residential area of \u200b\u200bEmerald Bay was used to save the lives of those who refused to go away.
Logistics . 7,000 firefighters were in the area. Undertook the bulldozers to remove combustible materials from the heath around Malibu, and it was great use of a different number of Bell-412 helicopters, capable of carrying 1,400 litri di acqua, e di aerei C-130, i quali possono trasportare 11.000 litri di sostanze chimiche utilizzate per sopprimere le fiamme. Tuttavia, i rischi erano troppo grossi per poter volare di notte.
La strategia per combattere l'incendio consisteva nella creazione di una serie di confini, mantenuti contro le fiamme da linee di pompieri insieme ai loro 250 mezzi. Si allestiva un posto di comando sul lungomare. Ma diverse volte, le linee sono state spezzate dalle fiamme, e di fronte a questo pericolo, si è dovuto ritirare anche il posto di comando. A Las Flores Creek, le fiamme passavano nel vento sopra i pompieri, i quali sono rimasti quasi circondati.
Gli incendi selvatici . Sebbene la protezione di risorse ad alto valore richieda l'impiego di un intervento sempre diretto e vigoroso, ogni giorno si dovrebbe formulare una nuova strategia per combattere l'incendio in base alle condizioni meteorologiche.
Un cosiddetto incendio selvatico brucia fuori controllo e minaccia le persone, gli insediamenti o altre risorse. Tramite barriere naturali o costruite, un incendio confinato viene limitato ad una determitata area, mentre il dilagarsi di un incendio contenuto viene impedito da una linea di controllo. Se quest'ultimo avvolge tutta la zona in fiamme, si ha un incendio diretto. L'incendio di Malibu fu prima contenuto e poi diretto.
Quando bruciano i rami e le foglie di un albero si ha un incendio di corona, che può divampare in rapporto alle fiamme in superficie (incendio dipendente) o propagarsi direttamente da un'albero all'altro (incendio scorrevole). La maggior parte degli incendi nella macchia mediterranea sono incendi dipendenti di corona e incendi di superficie, e possono causare incendi nel terreno ("ground fires") se il materiale combustibile giace sul terreno in uno strato spesso e consistente. I back-burns ("incendi ripassanti") possono avvenire se il materiale combustibile non viene interamente consumato dal primo passaggio delle fiamme, e se il vento cambia direzione tale da rispingere l'incendio indietro. I venti forti possono causare gli incendi a chiazza quando essi gettano frasche brucianti davanti alla linea del fuoco. Nella macchia, la temperatura dell'incendio può raggiungere 1100EC.
A Malibu si ebbe un incendio di superficie con elementi di incendio di corona che si autopropagava da un albero ad un altro. La radiazione e la circolazione dell'aria stimulava l'incendio a propagarsi sulle colline, non soltanto a progredire verso il mare spinto dal vento. Come spesso accade, le irregolarità del vento e della distribuzione territoriale di materiali combustibili spingevano il fronte dell'incendio in forma irregolare caratterizzata dal frequente scoppio di incendi a chiazza.
L'erosione accelerata e altri effetti ambientali . Dieci giorni dopo l'incendio a Malibu, la caduta di 4 cm di pioggia in 24 ore diede luogo ad un episodio di erosione accelerata nella zona bruciata, compresa una serie di colate of mud houses and took away a part of the coastal road.
When vegetation burns the Mediterranean, it distills some natural chemicals that waterproof the soil with a hydrophobic layer. At the same time the destruction of green vegetation by erosion, which is enhanced by the increased flow of water on the barrier layer. The result is a series of mudslides that come with the first rains after the fire.
The high frequency of fires, the power of deadly landslides and the continued urbanization of new areas determines the decline of populations of species of rare birds. California fires of 1993 have left a fragmented habitat so che alcune specie di avifauna rara probabilmente non riusciranno a superare la scossa.
Il rischio di incendio in California . Ogni anno circa 3.000 incendi scoppiano nelle macchie della California meridionale. Molti sono di origine dolosa, ma meno del 20% delle persone colpevoli vengono soperte.
Come altrove, in California il rischio di incendio raggiunge un massimo nelle aree tra le zone di nuova urbanizzazione e il terreno ancora in stato naturale. Sono delle aree di massima crescita demografica e quindi di grande frequenza degli incendi, i quali causano danni ingenti e costosi nel giro di poche ore. Circa un terzo del costo consiste nelle spese per combattere l'incendio.
Buone risposte al rischio . The devastating fires of 1970 and 1977 had resulted in the creation of the California Firescope, a structure based on a centralized Incident Command System (ICS) and a multi-agency Coordination System (MACS), with a center with a sophisticated system Fire Information. The emergency intervention is based on weather forecasts and infrared surveillance of areas of potential fire. In the case of the rapid development of a large fire, the key to effective intervention is the system of mutual assistance between the various regional and local authorities, which guarantees a certain level of timely workforce against the flames.
Un'incendio catastrophic stimulates certain measures, how to broaden the access routes to areas most at risk, buy more equipment (like air Canadian CL-215 "super scooper", which is able to lift 6,000 liters of water in just 12 seconds), and improve planning and coordination of emergency operations. Also, because burning some houses and spare others, the fire can also demonstrate the utility of standards for reducing inflammability of building materials.
good response to risk . In California, as elsewhere, the use of appropriate fire regulations varies from place to place as the tendency to follow them. After the great fire of 1991 in Oakland, 25% of homes not rebuilt were the measures required by new legislation to prevent the spread of the flames.
Repeated public opinion polls in California showed a progressive increase in the sensitivity of the fire problem, but without a tendency to take sufficient measures to mitigate the risk.
Despite a great plan for insurance against fire damage, insurance companies have done little to encourage their customers to reduce the risk of fire. In summary, some researchers argue that the offer of generous loans and repayments has almost rewarded the owners of homes burned for failing to mitigate the risk.
avalanches in the Alps EUROPEAN
Executive Summary . Diverse valanghe di neve uccisero 150 persone nel Dipartimento francese di Savoia, nell'alta valle del Rodano in Svizzera e nel Tirolo austriaco. In ciascun paese i disastri diedero luogo a nuovi programmi di mitigazione del rischio di valanga.
Gli eventi di febbraio 1970 . Nelle Alpi europee i disastri causati dalle valanghe di neve avvengono in base allo spessore della coltre di neve, alle condizioni meteorologiche e all'uso del terreno in fondo ai versanti interessati dall'instabilità. Avvengono due tipi di catastrofe. Nel primo, le condizioni meteorologiche favorevoli alle valanghe durano a lungo, dando luogo ad un alto rischio che continua per lunghi periodi. Ad esempio, nell'inverno del 1950-1, 650 persone morirono in una serie di valanghe alpine che complessivamente distrussero 2.500 edifici.
Nel secondo tipo, disastri provocati da singoli eventi che interessano soprattutto gruppi di sciatori o alpinisti avvengono negli anni di rischio generalmente basso. Così, in Svizzera nel 1960 un gruppo di 88 lavoratori morirono sotto una valanga proveniente da un ghiacciaio.
L'anno 1970 offre un buon esempio del primo tipo, una stagione disastrosa, che induceva ad una rivalutazione generale delle precauzioni contro le valanghe alpine.
Nel febbraio del 1970 le temperature nelle Alpi oscillavano continuamente intorno allo zero, con notevoli inalzamenti quotidiani. Nelle aree ad alta quota e sui versanti piuttosto ripidi, questa situazione provocava growing instability in dense layers of snow earlier by a heavy snowfall.
On February 10, 42 people died and 60 were injured by an avalanche in Val d'Isere in the French department of Savoie. It was a movement of powder snow, with a 45-90 front off me when to stop a thickness of 3.65 m. Invaded a youth hostel, where thirty young people died asphyxiated or crushed, while another dozen people was swept away from outside the building. The hostel was built only 7 years before his site was not considered a place of particular risk and was also protected on top by a series of concrete blocks, which, however, does not help stop the avalanche.
From the French authorities, the rapid recognition of a potential danger for the immediate closure of Val d'Isère. A helicopter was able to evacuate the wounded once before worsening weather conditions such as to block any possibility of flying. The first convoy of cars coming out of the valley was hit by a new avalanche, while a similar event elsewhere killed a child. As soon as possible, the authorities evacuated 5,000 people from hotels and residences in the area.
Following the disaster took issue much on the apparent reluctance of French authorities to invest in structural measures for mitigation of avalanches (tunnels, fences, roofs, etc.). When you invest a lot in the promotion of winter sports. Having recently moved from Chambéry to Grenoble, the National Institute for Research on Snow had just lost his representative in Val d'Isere.
Later that month, in Switzerland 11 people were killed and 19 injured by an avalanche that had not seen such a site in that more than half a century. Despite that 500 troops and 12 dogs to search for survivors, it was not easy to evacuate the victims amid the snow and the continued risk of further avalanches.
February 25, a village on Mount Cenis in the French Alps was hit by an avalanche 10 times greater than that of Val d'Isère. Seven lives were lost. The movement was immediately preceded by a pressure wave that demolished several buildings. It took 13 hours to extract the victims from the snow. The same day an avalanche killed two people in the Tyrol in the middle of the main street of St Leonhard Pitztal am. In the Austrian provinces of Tyrol and Vorarlberg avalanches were so widespread as to prevent the evacuation of 14,000 people.
Meanwhile, the Swiss made extensive use of explosive material thrown from helicopters to trigger avalanches before the snow accumulation can be dangerous. In Italy, meanwhile, seven soldiers died in an avalanche during their exercises.
The events of April 1970. On April 15, 1970, when temperatures were unusually alte per la stagione, una valanga a lastre di ghiaccio colpì un sanatorio nell'Alta Savoia francese. Si dovettero impegnare 21 ruspe per setacciare le macerie, da cui furono estratte 72 salme, 56 delle quali bambini. Alcuni ulteriori movimenti di neve, ghiaccio e macerie ferirono 13 soccorritori.
Il rischio valanga nelle Alpi . Nelle Alpi europee, come in altre catene montuose, le cifre degli infortuni per valanga variano parecchio da un anno all'altro. In Svizzera, ad esempio, la media è di 17.480 eventi e 24 morti, ma questo può variare di diversi ordini di magnitudine.
Le popolazioni indigene continuano a diminuire nelle aree alpine, mentre aumentano quelle saltuarie, le quali non sempre conoscono bene i rischi. In solo 30 anni alcuni centri sciistici nelle Alpi sono cresciuti di 20-50 volte rispetto alle loro dimensioni nel 1945. Intanto, le popolazioni di vacanzieri aumentano proprio nel periodo di massimo pericolo di valanga.
Nell'inverno del 1970 i rischi variavano con le condizioni meteorologiche. In febbraio avvenivano valanghe di neve polverosa associate con il freddo. Erano di una rapidità tale da causare onde di pressione capaci di travolgere persone ed edifici. Invece, le valanghe di aprile erano composte di lastre di ghiaccio, le quali generavano pressioni di impatto in rapporto con la loro più alta densità. Gli eventi di febbraio erano la conseguenza di tempeste, quelli di aprile di scioglimenti.
Il salvataggio . Si riscontravano grande difficoltà di estrarre le vittime dalla neve delle valanghe di febbraio 1970. I cani, che in Svizzera trovano il 50% delle persone sepolte sotto la neve, non riuscirono a individuare una persona intrappolata a più di un metro sotto la superficie. La neve più profonda richiede le sonde con pali, sonar oppure sensori ad infrarosso, ma la ricerca diventa assai difficile quando una forte nevicata è in atto.
La mitigazione . Le valanghe del 1970 hanno dato luogo ad un potenziamento delle previsioni del tempo che causa le valanghe. Ma gli eventi di aprile 1970 non furono di un tipo particolarmente prevedibile, ed inoltre una previsione è valida soltanto se viene collegata con un programma di structural and non-structural mitigation, including the planning of human settlements and the evacuation of populations during periods of highest risk.
For many years the French and Swiss have collected and compiled data on avalanche risk charts at scales ranging from 1:10.000 to 1:50.000. During the 70 municipalities of Alpine France undertook to plan their urban growth on the basis of risk mapping of flood by prohibiting new construction in areas "red" and limiting the areas 'blue'. However, some similar initiatives in Switzerland have been hampered by the division of resposabilità for urban zoning between the governments of the cantons and the federal state. This situation brought a remarkable heterogeneity of planning legislation against the danger of avalanches.
Despite this, the Swiss have made extensive use of structural methods nonstrutturali and mitigation of avalanches, using a good combination of measures. Instead, the Italians, for the most part, have used expensive structural measures, which were contrabilanciate by massive deforestation and a major development of sports facilities.
In summary, the Alpine winter disaster of 1970 represented an excellent window of opportunity "to introduce certain mitigation measures. However, the expansion of tourism and mountain sports has helped keep fairly constant number of disasters due to avalanches, although their amount is decreased due to better forecasting and planning against the Avalanche.
Aberfan TO LANDSLIDE IN WALES
brief summary. A pile of debris from a coal mine collapsed on Aberfan, a mining town in South Wales. The landslide destroyed 18 homes and an elementary school and killed 116 children and 18 adults. The event
. At 09:15 of October 21, 1966, landslide 117,000 m of debris from a coal mine and piled in a heap of height 67 meters. In a series of waves, the water-saturated debris flow traveled at 15-30 km / hr along a slope E. slope of 12.5 Approximately 75,000 m of debris stood at the foot of the heap, but 42,000 ft, traveled another 100 meters and came in the middle of the adjacent village of Aberfan (pop. 4,000), forming a deposit often 7-9 meters. The debris flow
demolished two houses and crushed their occupants. Later destroyed a school full of children and 18 homes in the country. Of the 144 people affected by the flow is not saved. Among the dead were five teachers and 109 school children aged between 7 and 10 years. Seven other children died and 29 other children and six adults were injured, some seriously. Several houses were flooded by water coming from the lava flows and broken un'acquedotto.
Conditions antestante . Since the '20s the debris from the mine had been stored in 7 piles of height between 17 and 67 m. In 1962 he began a process of refining of coal that left pieces of scrap were later dumped in seventh pile of ashes which made up 39% and 6-8% water. Consequently, this combination had a low density and was saturated with water from a natural spring located mainly in the mass of debris. No report was ever made to geological sites of the seven piles.
In the 70s Britain produced and released into open some 50 million tons of rock material of the type that has crumbled to Aberfan. In 1939 about 180,000 tons of debris from a mine near Aberfan had slid for a distance of 400 m across the main street of the area. But in 1966 the villagers took care of most of the risk of flooding, given that several times during wet periods the water flowed in the streets and entered houses. In fact, despite the advent of small movements in 1944 and 1963, the engineers did not anticipate that happening in coarse materials flows as well as those of the heaps of debris from the mines.
The reaction to the disaster. The disaster was followed immediately by a massive "response to convergence", where the labor force and help arrived at Aberfan in excess. Accumulating a fund for the victims, from 1,750,000 in donations, not only from all over the UK but also from 40 other nations. Despite a series of disputes between the trustees and the survivors of the disaster, the money was well used to compensate those who denounced the material losses, to create a memorial to the victims, and to build a community center for the country. However it could not mitigate the fact that a very supportive community had lost almost an entire generation of his children.
A question of responsibility. At first, neither the Welsh Office of the British government nor the National Board for Coal (NCB), admitted responsibility for the disaster. The villagers of Aberfan were fighting with all their strength to prosecute the guilty, but was found a thick resistance from the authorities. In addition, the NCB refused to raze the mounds of debris, which continued to constitute a danger to the country is a symbol of disgrace. Finally, public opinion forced the government to allocate funds for the removal of all the piles 7. The court of inquiry found 9 dell'NCB officers guilty of gross negligence, but the law was not that they could be prosecuted, and in fact even the dell'NCB Director had resigned. In summary, despite clear indications to the contrary, for many years before the disaster, the NCB repeatedly assured the people of Aberfan that there was danger of a collapse in heaps of debris. Following the disaster denied any responsibility for it was not forced by the court to admit his guilt. But the court failed to prosecute persons who with their actions had caused the disaster.
A notable aspect of the disaster in Aberfan is the total lack of plans, regulations, and standards expertise to manage the process of unloading around the mines. As usually happens in such cases, immediately after the disaster the laws were updated to remedy. But by then the eminent engineer Prof. Alan Bishop of Imperial College, London University, had shown by calculation and physical models which, under the circumstances, Aberfan era un disastro inevitabile.
Aspetti umani della tragedia . Dato un certo consenso al fatto che i minatori pagano un prezzo sproporzionato per la creazione del benessere della società, gli abitanti del Regno Unito e di altri paesi provavano grande compassione e simpatia verso Aberfan. Essendo profondamente scossi dal disastro, molti abitanti, poco abituati a stare al centro dell'attenzione, non erano felici dell'invadenza del mondo esterno. Però, la solidarietà del paese ha retto e poche persone e famiglie si sono traslocate al di fuori della zona. Ma tale era la scossa psicologica che molti dei sopravissuti di Aberfan negavano per anni che la tragedia fosse successa. Come nella colata detritica di Buffalo Creek, Pennsylvania (Also from a mine), which killed 118 people in 1972, among the victims of Aberfan was noted a "survivor syndrome", consisting of an inner terror, a tendency to relive the tragedy and a state of "psychological paralysis "or a" temporary collapse of ego. "
Finally, the deadly mudslides caused by mining activities continue to happen, as the Italian case is one example of the Val Was, 1985, in which 264 people died.
LANDSLIDE IN ANCONA
brief summary. The landslide of 1982 interested in 341 acres of the northern city of Ancona. It destroyed 476 buildings and left 3,661 homeless.
The event
. During the night of December 13, 1982 a landslide interested in the slope of the hillock at the north side of the city of Ancona and Marche on the coast of the Adriatic Sea. 294 residential buildings were damaged, consisting of 1,025 apartments and 182 other buildings, including two hospitals, a gym and the Faculty of Medicine, University of Ancona, some churches, a cemetery, several factories, a few farms, a barracks of the forces of 'order, and some workshops and industrial applications. The victims were 3,661, of whom one patient died when he had to be evacuated from the intensive care unit of one of the hospitals affected by the landslide. The town of
Borghetto had to be entirely demolished, and some parts of the suburbs of Ancona Posatora, Pinocchio, Palombella and Towers suffered serious damage. Severe impacts were also found by the road through the area and the Adriatic railway, which passes over the foot of the landslide. In addition, light pipes, gas and electricity were cut. The cost of the damage was estimated as £ 1 trillion.
causes. The move came after several weeks of rain. While the seismic shaking could have contributed to the destabilization of the slope, was not a trigger for the movement of 1982. The causes included the long-term effect in increasing coastal erosion the steepness of the slope, and mismanagement of the infiltration of rain and drainage of the slope in areas of recent and current urban growth. The main cause was the high short-term pore pressure of soil moisture, especially at the top of the slope.
History . At the point the slope of the landslide Montagnolo reaches 251 m above sea level, is off my 1400 has a slope that varies from 9 to 18E. The area was affected by problems of stability since 1770, when postal links were interrupted frequently by surface movements on the old road through the area. At the beginning of the twentieth century, a landslide destroyed 16 hectares of the tannery Barden and licked the rail at the base of the slope. An engineer called by the State Railway to make a geological survey concluded that the slope of the exceptional measures needed to ensure its stability. Barden located upstream of the landslide, the old house is placed upstream spectacularly revolved around 3E, constituting a clear testimony to the instability of the area.
In the 70s the General Regulatory Plan of Ancona took a large urban sprawl to the north of the city. In 1970 an employee of the Geological Survey of state he predicts accurately the mechanism and extent of the landslide (with 12 years in advance) and suggested a series of engineering measures to consolidate the area at risk. However, very few of the proposed works were built. Instead, the urbanization of the area continued with the construction of houses and buildings in the middle of the unstable area and the faculty of medicine at the foot of the old landslide Barden. Further geotechnical report, published in the Bulletin of the Italian Geological Society in 1974, concluded that the area was essentially stable, although, strangely, the data presented in that work showed exactly the opposite.
The mechanism of movement. The slope of a lithology Montagnolo there is a little complicated, which is composed of clay cracked blue board, with varying degrees of compactness, and a slightly consolidated sand. The geological investigations following the disaster concluded that the landslide took place on a cutting plane located up to 120 m below the surface of the slope. However, data from drilling and inclinometers did not confirm this hypothesis, and is more likely that the extraordinary size of the movement is a progressive movement of plates of land due to a change in the type "shear deformation" at a depth no greater than 40 -45 m, with involvement of the rest of the slope because of the shift of its overall balance.
teleosservazione The infrared shows the presence of two substantial patches of soil moisture, one just below the crown of the head of the landslide detachment, and the other near di una trincea di subsidenza che si apriva in mezzo della frana a causa dei movimenti distensionali franosi e della presenza di una faglia normale che attraversa il versante in direzione nord-sud.
Il comportamento degli edifici . La grande frana di Ancona ha fornito molta informazione sulla reazione di edifici di vari tipi alle forze e ai movimenti indotti da un grosso e complesso movimento franoso. Le strutture più vecchie erano di mattoni rossi cotti, di modeste dimensioni e quasi prive di fondazioni. Invece, le strutture più moderne erano per la maggior parte di cemento armato, sebbene nella zona vi fosse qualche struttura in acciaio. La spaccatura dovuta alla frana tendeva ad esser unidirezionale e a risultare da una pressione sostenuta causata dalla subsidenza, dal rigonfiamento o dalla spinta proveniente dal movimento franoso. Dove la subsidenza differenziale ha interessato le fondazioni, un edificio con struttura portante in cemento armato poteva inclinarsi fino a 6,5E senza crollare, ma nella maggior parte dei casi un'inclinazione di 2-3E era sufficiente per compromettere la stabilità dell'edifico irrimediabilmente. Se i pannelli della facciata fossero ben ancorati alla struttura portante, un edificio in acciaio poteva resistere la conpressione senza crollare fino ad un metro di deformazione.
In genere, gli edifici in cemento armato funzionavano meglio di tutti gli altri sotto il carico della frana, dato che il grado di integrazione delle loro strutture permetteva loro di resistere massive forces. The risk was highest where buildings were located through the steep, landslide, and then where they suffered from severe differential movements, which might tilt, swivel, compression or distension of their structures.
Conclusion. In summary, the Ancona landslide disaster was another highly anticipated and in fact often provided with ample time in advance. While interpretations may vary, the data showed very clearly that the presence of a high degree of risk of instability were freely available throughout the period of urban expansion antestante the disaster. In the years before and after the event, almost every aspect of the disaster was politicizzato, con l'effetto che si stentava e si stenta ancora a separare la realtà oggettiva dalle speculazioni e dalle opinioni prive di fondamenta. Con il senno di poi, la questione principale ancora da risolvere è quanto il disastro risultava da una trasformazione ambientale basata su un'ignoranza del rischio di frana e quanto invece essa risultava da una speculazione che deliberatamente ignorava il rischio. La catastrofe, con il suo elevato costo in termini di denaro pubblico, dimostra il pericolo, non soltanto di una mancanza di controllo ambientale dei processi di urbanizzazione, ma anche dei rischi inerenti a un controllo in cui il colpevole è anche il giudice e la giuria del risultante processo.
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