Does praying help prevent natural disasters?

Saint Januarius is the patron of Naples and annually a flask of his (supposedly) blood is presented during a public procession in the city. If, so the legend goes, the dry blood becomes liquid again the city will be spared of any disaster and misfortune. It must be said that the supposed premonitory miracle and its interpretation is very complicated. Factors like timing, how much and how the blood liquefies, color and density of the resulting liquid play a role.

Fig.1. The eruption of Vesuvius in 1631, Saint Januarius is shown above the vulcano. He's a silent guardian, a watchful protector.... most of the times.

The first supposed miracle happened in 1389 and in 1924 geologists Giovanni Battista Alfano (1878-1955) and Antonio Amitrano compiled a list, looking on how well the premonitory signs correlates with disasters or the lack of such. In years where the miracle failed to happen Mount Vesuvius erupted eleven times and nineteen earthquakes hit the city. In years when the miracle happened Vesuvius erupted just five times. So it seems that divine protection works half the times. 
Also whenever Vesuvius seems to become active a procession with the relics of the saint is organized to implore divine protection.These processions helped diplomat and amateur vulcanologist Sir William Douglas Hamilton (1730-1803) to reconstruct the activity of Vesuvius in recent history.

Fig.2. "The recent eruption of Vesuvius: scenes of terror and piety in the face of the eruption", by Achille Beltrame (1871-1956), cover of the newspaper "La Domenica del Corriere" April 1906.

Naples is not the only city with a holy protector. In Catania it´s Saint Agata. According to local folklore a veil of the saint has the power to stop a lava flow. During the disastrous eruption of Mount Etna in 1669 Saint Agata was invoked. For a time the lava flows could be diverted by a group of brave men, building dams of lava rocks in front of the advancing flow and digging alternative paths, also the walls of the city of Catania resisted. But finally the lava entered in a breach of the walls, claiming 15.000 victims.

Fig.3. Fresco by painter Giacinto Platania (1612-1691) of the eruption of Mount Etna in 1669, Platania witnessed the eruption himself and the painting is quite realistic, showing the lava flows stopped by the city walls.

Still in 1971 divine protection was claimed for the city of Sant'Alfio, near Catania, and it apparently worked this time. 

As why those inconsistent results over time - as they say the lord works in mysterious ways.

Charles Darwin in Rio de Janeiro and the Geology Of Sugarloaf Mountain

The Sugarloaf Mountain (aka: Pão de Açúcar) rising almost 400m above Rio de Janeiro is composed of granitoid rock – a plutonic rock formed by the slow cooling from magma and composed mostly of the minerals quartz, feldspar and mica.
 

Charles Darwin, visiting Rio de Janeiro in 1832, describes in details this rock “- This whole district is almost exclusively formed of gneiss, abounding with garnets, and porphyritic with large crystals, even three and four inches in length, of orthoclase feldspar: in these crystals, mica and garnets are often enclosed.”
 

Fig.1. View of Rio de Janeiro with Sugarloaf Mountain as seen from the Corcovado by HMS Beagle artist Augustus Earle. 

Granite shows commonly no preferred orientation of the minerals, however Darwin noted that the granite of Rio de Janeiro seems to be more of a gneiss with a weak developed “stratification and foliation” of minerals, as he continues “The mountains of gneiss-granite are to a remarkable degree abruptly conical, which seems caused by the rock tending to exfoliate in thick, conically concentric layers: ...”
 

Indeed the Sugarloaf is, as correctly described by Darwin, composed mostly of augen-gneiss, a metamorphic rock with single large, often elongated, crystals, resembling eyes in a finer matrix of smaller crystals, therefore the name as auge means eye in German.

Fig.2. Simplified geological map of the Sugarloaf and surrounding bornhardts, from MIGON 2010.

The Sugorloaf is also evidence for plate tectonics. 560 million years ago, when the ancient supercontinent of Gondwana started slowly to break apart, large magmatic bodies intruded into the weakened crust, feed from below by the Tristan da Cunha hotspot. 

Fig.3. Large Igneous Provinces (LIP) and correlated hotspots. Magmatic rocks of the same type can be found on both sides of the Atlantic Ocean, showing that South America and Africa once were one single continent.

Slowly cooling in the upper crust these magmatic bodies formed a large granitic pluton. During the movement of the continents parts of the pluton broke apart, as we find the same type of rock along the coasts of South-America and of Africa, also some metamorphism and deformation of the rocks occurred and the cleavage of the gneiss formed. Later finally the metamorphic pluton was pushed upwards and erosion started to form the modern landscape of Rio with the hard augen-gneiss towering above weaker and more erodible rocks.

The Dog´s Cave, Animal Cruelty and an unseen Volcanic Killer

The Grotta del Cane (the Dog´s Cave) is a short, 9m deep, artificial gallery located on the rim or the basin of Agnano near Naples. The basin is in reality the remains of an 8.000-4.000 year old collapsed volcano, just one smaller caldera of the Phlegraean Fields.

 

Fig.1. The Phlegraean Fields with the caldera of Agnano located almost at the center, from SUESS, E. "Das Antlitz der Erde" (1892).

Since antiquity the area is known for it´s volcanic activity, like hot springs and fumaroles, called mofettes.
It´s also famous because inside the dog´s cave small animals like dogs and bird will slowly suffocate. Already the Roman poet Vergil (70-19 BC) writes of the nearby lake of Averno:

"There was a deep stony cave, huge and gaping wide,
sheltered by a dark lake and shadowy woods,
over which nothing could extend its wings in safe flight,
since such a breath flowed from those black jaws,
and was carried to the over-arching sky, that the Greeks
called it by the name Aornos, that is Avernus, or the Bird-less."

Naturalists from Antiquity until the Renaissance know of the strange phenomenon and speculated about toxic vapors coming from the underground, killing smaller animals. German polymath Athanasius Kircher (1602-1680) suggested that “Ochre, Sandrak*, Orpiment and Arsenic” compounds, known at the time to be toxic (and very popular as pigments to paint), were to blame.
In the early 19th century naturalists in self-experiments determined that below a certain level in the cave they experienced a strange dizziness and started to lose feelings in their legs. Those were recognized as symptoms of a carbon-dioxide intoxication. The invisible and odorless carbon-dioxide is heavier than normal air and tends to flow to the bottom of wells and caves. 
The gas emanates from the volcanic underground and accumulates in the dog´s cave. At the entrance the layer of carbon-dioxide is just sufficiently thick to suffocate smaller animals, deeper in the cave it can become dangerous also for humans. 

The dog´s cave became a popular and somehow macabre tourist attraction in the 18th-19th century. Visitors could buy a dog from a nearby shelter and observe how it would become unconsciousness and suffocate inside the cave – when not saved in the last moment by throwing it in the nearby lake of Agnano (today dried up). The cold water would revive the poor dog in most of the cases...

 

Fig.2. Demonstrating the deadly effects of the dog´s cave, from “The book of curiosities: containing ten thousand wonders and curiosities of nature and art” (1822). 

*Sandrak is actually a resin used to fix pigments

Literature:

KROONENBERG, S. (2013): Why Hell Stinks of Sulfur: Mythology and Geology of the Underworld. University of Chicago Press: 352