Field of Science

The Geisha and the Tsunami

More than a month has passed since the earthquake and the Tsunami that devastated the coast of north-eastern Honshu.
After the first shock people begin to ask if the extent of destruction and number of victims (more than 14.000 confirmed dead and 12.000 people missing) could be predicted. There are various hinds that can help to produce a risk
map - there is geological evidence like fossil Tsunami deposits, there are in prehistoric time maybe myths and legends surviving in oral traditions, there are in historic time written stories in chronicles, scientific observations and measurements in charts, there are monuments, but there are also the eyewitnesses' reports of survivors.

In various newspapers and online media the accounts of many survivors of the last Tohoku tsunami were reported, the story of the geisha Tsuyako Ito is remarkable because it provides us with a scale how often Japan was hit by such disasters - even in the span of a single human life.
With her 84 years she experienced three tsunamis who hit the city of Kamaishi and as a girl she had listened to her grandmother's tales of the great 1896 tsunami.

"My grandmother said that a tsunami is like a wide-open mouth that swallows everything in its path, so that victory comes to those who run away as fast as possible."

The German newspaper "stern" published this old photography of a performance by Tsuyako Ito, she lost everything in the devastating Tsunami except her memories - and she promised not to surrender.

Her mother carried her on her back to safety at the time of Ito's first tsunami in 1933. This time, her fourth and "most frightening" tsunami, she was saved by an admirer who carried Ito on his back to higher ground.

The warnings of such experiences unfortunately last only a short time, according to the Japanese Yotaru Hatamura who studied ancient traditions about Tsunamis in Japan:

"It takes about three generations for people to forget. Those that experience the disaster themselves pass it to their children and their grandchildren, but then the memory fades," he said.

After the earthquake that devastated Tokyo in 1923 and San Francisco in 1906 the opportunity to rebuild the cities following antiseismic principles was abandoned to provide a fast reconstruction.

We shouldn´t ignore or forget...

Online Resources:

ONISHI, N. (08.04.2011): Geisha survives with help from an admirer - Guardian of a local culture has lived through four tsunamis. (Accessed on 25.04.2011)

April 26, 1986: Chernobyl

"Now I know the fiendish fable
That the golden glitter bore;
Now I shun the spangled sable
That I watch’d and lov’d before;
But the horror, set and stable,
Haunts my soul for evermore."
"Astrophobos" (1918) by H. P. Lovecraft (1890-1937)

Saturday, April 26. 1986, at 1:23:40 a.m. the Reactor No. 4 at the Wladimir Iljitsch Lenin Atomic Power Station near the city of Chernobyl in modern Ukraine experienced a minor accident - the reactor exploded and parts of the nuclear fuel were hurled into the atmosphere contaminating with radioactive particles the surrounding landscape.

Fig.1. Chernobyl Disaster Aftermath after Wikipedia.

In the early hours fire-fighters, doctors and nurses rushed to the plant not aware of the danger of radioactive contamination. Realizing the extant of the catastrophe in the next days more than 16.000 policemen and military personnel where sent to the power plant to extinguish the fire, remove the radioactive debris and enclose the ruin in a provisory protection shell, these people are remembered today with the laconic term "likvidatory".
Confirmed 31 people died from radiation sickness in the first days, later estimated numbers range between some thousands sickened people in the following years, the long term effects on the Sunday afternoon evacuated 100.000 people is still poorly understand, however an increase of various cancer varieties is blamed on the radioactivity.

The effects on the fauna and flora inside the evacuated region became an investigation field for geneticists, ecologists, botanists and zoologists.
Even regions thousands of kilometres distant von Chernobyl are still today contaminated with radioactive particles and elements transported by the wind in a gigantic plume above Europe.

25 years later the atomic remains of reactor 4 is still one of the most dangerous and expensive ruins in the world. The old shell was a provisory construction, so a new project was initiated; in 2013-2015 the new sarcophagus will be terminated, projected to last for some hundred years and to enclose radioactive scoria, dust and particles inside, how long the radioactive content of the destroyed reactor will be threatening human health is unknown - the decay of some of the radioactive elements is measured in geological time...

A geologist riddle #13

An easter egg georiddle - what supposed and unusual event is depicted by this illustration of 1733:

The Younger Dryas impact hypothesis

The cause(s) that led to the extinction of most of the larger mammals that roamed the Pleistocene world are still today unknown. Many different hypotheses were proposed, from human overkill to climate change, but more unusual was an idea largely publicized in 2007.
Geophysical studies presented in spring 2007 suggested that perhaps an extraterrestrial bolide vaporized in the Earth's atmosphere caused the extinction of the North American Megafauna some 13.000 years ago.
In 2009 this hypothesis seemed to be further confirmed by subsequent findings.
This and other interdisciplinary research presented various sedimentological features found in peat layers at nine excavated sites of the North American continent and one site in Belgium and thought to be associated with impacts of meteorites on earth.

Fig.1. Profiles of sites in North America with proposed sedimentological evidences for an impact event some 12.900 years ago. The diagrams show the concentration of magnetic particles, microspheres, particles of coal and glass and some elements rare in the earth's crust but common in meteorites (such as iridium, chromium and nickel). The highest values are apparently found in a distinct single thin layer, after FIRESTONE et al. 2007.

1) An increased concentration of iridium, a rare element in earth's crust bu
t common in meteorites.

2) Metallic particles and grains, also carbon microspheres concentrated in a thin layer, interpreted as remains of the impacted meteorite and the recrystallized molten rocks of the bolide and crust.

Fig.2. and 3. The metallic micrometeorites with a diameter between 100 to 150 µm found in one of the profiles (Blackwater Draw) showed a high content of titanium and nickel typical for extraterrestrial material (FIRESTONE et al. 2007), also shown the carbon microspheres interpretated as the remains of the molten and recrystallized bolide.

3) A particular and rare modification of carbon - Lons
daleite - in shape of microscopic nanodiamonds with a hexagonal crystalline structure formed only under very high pressure as experienced during an impact.

4) Another exotic modification of carbon, the Buckminsterfull
erene or buckyballs, a modification of carbon that supposedly can be created only under great heat conditions.

5) Dark layers of peat or sediments rich in organic matter were interpreted as the remains of burned vegetation by megafires ignited by t
he heat of the impact.

6) Recovered Pleistocene bones of mammoth and bison showed features that were interpreted as direct effects of the explosion - small, 2 to 3 mm in diameter, holes in the bones with a burned halo and penetrated magnetic particles with a high content of iron and nickel of unusual isotopic composition.

To explain the lack of the most compelling evidence - the impact crater- it was suggested that the bolide exploded above or on the Laurentide ice shield, leaving behind no visible trace.
7) An alternative suggestion positioned a debris field in the Carolina Bay area along the south-eastern coast of the United States. The Carolina Bays include thousands of circular to elliptical depressions across the coastal plain of still unknown origin (some authors suggested even spawning fish).

The most intriguing conclusion of the Younger Dryas impact hypothesis: The heat released and the shock waves of the impact caused the extinction of the North American Megafauna and the annihilation of the Clovis-culture possibly in two ways, by directly killing animals and igniting large scale firestorms and in a second moment by the partial melting of the ice shield of North America and Greenland. The large amounts of fresh water released in the Atlantic Ocean caused an arrestment or a slowdown of the warm Gulf Stream, starting a 1.500 years long climatic reversal recognized especially in Europe as Younger Dryas stadial (12.900-11.600 cal BP), an important phase of cooling recognized in glacier advances and vegetation shift.

Fig.4. The isotopic values as proxy of climate recovered in ice cores from Greenland show a distinct phase of climatic reversal between 12.900 and 11.600 years ago. The sudden beginning of this period named Younger Dryas stadial is still poorly understand, the influence of changing patterns of the marine currents in the Atlantic at the end of the Pleistocene are the most suggested and likely triggers of such an abrupt climate change (Greenland Ice Core Chronology 2005 released 10. March 2006).

The hypothesis experienced a positive and large attention in the popular media but got mixed reception from earth scientists during it´s official presentation in May 2007 at the congress of the American Geophysical Union.
The meteorite idea was however not completely new and already published in 2001 and in 2006 even in a own book - however with some pseudoscientific implications like glacial landscapes with drumlins or the North American Great Lakes as the direct results of the impact.

Also focusing only on the research published in 2007 soon problems arouse. For example the methods used to identify some of the most compelling impact evidence, like the nanodiamonds, were questioned because the results of the analyses were explainable also by other, more earthly, materials.
More important - the impact hypothesis could only explain a local decline and extinction event for the American continent in a very short interval, maybe in few decades or centuries. However dated fossils seem not to support a unique and sudden extinction as proposed by this and many other catastrophist hypotheses. In a survey on 4.532 archaeological sites in Europe and Siberia and 1.177 dated remains of mammoth and mastodons in Europe, Siberia and North America the dates scatter between 45.000 to 12.000 years.
Estimating the development of the population of single species there seems to be various phases of increase and decline in numbers of individuals. The woolly mammoth for example reaches a population maximum some 16.000 to 15.500 years ago, this phase is followed by a slow decline 14.500 to 13.500 years ago, however isolated populations survived on islands and in northern regions of Asia even until historic times.

Apart of these general critics in 2011 a paper By PINTER et al. focused explicit on the single evidences as presented in 2007 and subsequent years and concluded that most of the claims can not be reproduced and the few reproduced evidences are not unequivocally related to an impact of an extraterrestrial bolide:

1) The iridium concentration was not measured in the bulk sediment but on single fragments or spherules thought to be of impact origin - this could falsify the apparent peak in the stratigraphic column. On some studied sites the concentration of iridium in the supposed Dryas interval was also surprisingly low. Despite the methodological error, these contradicting results are imputable to diagenetic alteration of the sediments and the iridium concentration is more likely of terrestrial origin.
More notable subsequent research failed to reproduce the single iridium peak.

2) Some of the carbon spherules resulted to be fungal spores or coprolites of arthropods. Subsequent research could not reproduce a peak or concentration of micrometeorites in a single layer, but the particles resulted to be distributed homogenous in the stratigraphic column, as more likely explained by the common background sedimentation from the interplanetary space occurring during geological times.

3) The supposed nanodiamonds resulted by further and more detailed investigations to be amorphous to polycrystalline carbon aggregates as produced during common wildfires, the presence of the particular carbon modification Lonsdaleite could not unequivocally proven in the sediments.

4) The presence of buckyballs was questioned because of methodological problems already in the original research and later investigations could not reproduce the results. Despite the dubious presence of the fullerenes, it is known that small amounts of this carbon modification can be produced by common wildfires, so even if buckyballs will be found, these are not unequivocally evidence of an impact.

5) Sediments rich of organic matter are not necessary produced by wildfires; common depositional environments like swamps can also produce thick layers with encoaled plant remains. Some proposed impact-related dark layers, supposedly rich of organic matter, resulted even to be coloured not by organic remains but by minerals. There is today no unequivocally evidence that the layers are connected to any wildfires after an impact.

6) Some of the bones with the supposed fragments of the bolide resulted to be older by nearly 20.000 years than the previously specified impact date. The fragments in the bones were not reanalyzed after the first claims and doubts arouse of the proposed origin.
It seems unlikely that such minuscule and fragile particles could penetrate earth's atmosphere and still impact on such a hard material as are the bones. In alternative it is well possible that the discovered particles are more likely diagenetic iron concentrations.

7) The explanation of the Carolina Bays as debris field is not supported by any discovery of extraterrestrial material in the area; also relative dating efforts showed that these depressions were formed probably during a long time interval. So if these features still remain mysterious an impact origin seems the most unlikely cause of origin.
Even radiocarbon ages achieved by the impact supporters showed significant fluctuations in the ages of formation, ranging from 6.500 to 700 years ago. This lead to the excuse that "the impacting object was ejected by a recent near-Earth supernova in which case carbon [was] enriched" modifying the radiocarbon age of the sediments.
Realizing the improbability and problems of such claims the Carolina Bays were rejected as evidence by most impact proponents.

The Younger Dryas Impact Hypothesis was adopted mainly by non earth-sciences related researchers and especially the mass media, who dedicated to the scenario even various TV-shows. Even if it was stated that some of the results were preliminary, it is still surprising how catastrophic theories are accepted uncritically by popular media.
However three years later it seems that most of the proposed evidence for the Younger Dryas Impact Hypothesis could not be reproduced by other teams and were evidence is available there are terrestrial, non impact related, interpretations possible.


BECKER (2007): Abstract: The End Pleistocene Extinction Event - What Caused It? Eos Trans. AGU, Abstract PP41A-03

BECKER (2007): Ice Age Impact. mp3 (4MB). (Interview by the Canadian Broadcast)

FIRESTONE, R.B.; WEST, A.; KENNETT, J.P.; BECKER, L.; BUNCH, T.E. et al. (2007): Evidence for an extraterrestrial impact 12,900 years ago that contributed to the megafaunal extinctions and the Younger Dryas cooling. Proceedings of the National Academy of Sciences of the United States of America 104(41): 16016-16021
KENNETT, D.J.; KENNETT, J.P.; WEST, A.; WEST, G.J.; BUNCH, T.E. et al . (2009): Shock-synthesized hexagonal diamonds in Younger Dryas boundary sediments. Proceedings of the National Academy of Sciences of the United States of America 106: 12623-12638

KERR, R.A. (2007): Mammoth-Killer Impact Gets Mixed Reception From Earth Scientists. Science 316: 1264-1265
KERR, R.A. (2008): PLANETARY IMPACTS: Did the Mammoth Slayer Leave a Diamond Calling Card? Science Vol.323 : 26

LEVY, S. (2006): Clashing with Titans. BioScience Vol. 56(4) : 292-298

PINTER, N.; SCOTT, A.C.; DAULTON, T.L.; PODOLL, A.; KOEBERL, C.; ANDERSON, R.S.; ISHMAN, S.E. (2011): The Younger Dryas impact hypothesis: A requiem. Earth Science Reviews. Article in Press
UGAN, A. & BYERS, D. (2007): Geographic and temporal trends in proboscidean and human radiocarbon histories during the late Pleistocene. Quaternary Science Reviews.26: 3017-3440

Online Resources:

MORRISON, D. (2010): Did a Cosmic Impact Kill the Mammoths? (Accessed on 23.04.2011)


"But the world itself is only a speck of dust. And man is tiny - helpless! How long has he been in existence? For millions of years the earth was uninhabited."

"Nonsense. The earth is as old as we are, no older. How could it be older? Nothing exists except through human consciousness."

"But the rocks are full of the bones of extinct animals - mammoths and mastodons and enormous reptiles which lived here long before man was ever heard of."

"Have you ever seen those bones, Winston? Of course not. Nineteenth-century biologists invented them. Before man there was nothing. After man, if he could come to an end, there would be nothing. Outside man there is nothing."

Chapter 3, George Orwell´s "1984" (1949)

April 20, 2010: Deepwater Horizon oil spill

An explosion on the BP-operated Deepwater Horizon oilrig in the Gulf of Mexico on April 20. 2010 and the subsequent oil spill for nine months has become one of the second-most presented, discussed and publicized environmental catastrophe in the last decades (the first would be Chernobyl).

Politicians, authorities and experts referred to the accident as "unprecedented" and were insecure of the amount of oil spilled, the area affected and the effects of the oil on the marine environment. One of the surprising consequences of an oil leak in 1.200m depth were large subsurface oil plumes, whose existence were first doubted or even denied.

Fig.1. The oil slick as seen from space by NASA's Terra satellite on May 2. 2010 (image from Wikipedia).

This posed a major problem in the estimation by traditional methods - areal or satellite images - of the oil amount released into the gulf.

The oil on the surface was more visible and BP tried to deny it, entrap it, burn it or disperse it with chemicals, however despite the efforts on April 29. first oil traces were spotted on the US-coast, which caused an immediate and immense media response.

The Deepwater Horizon accident is however not completely unprecedented, in 1979 a blowout from the Ixtoc I platform in the Bay of Campeche released for nine months in sum 454.000-480.000 tons of oil into the water - the world's largest peacetime oil spill until the Deepwater Horizon accident with estimated 500.000-627.000 tons.
Many of the effects and problems observed at the Ixtoc I accident however were seemingly forgotten, as it seems that today the consequences of the Deepwater Horizon accident are already forgotten.


JERNELÖV, A. (2010): The Threats from Oil Spills: Now, Then, and in the Future. AMBIO 39:353-366
SAFINA, C. (2011): The 2010 Gulf of Mexico Oil Well Blowout: A Little Hindsight. PLoS Biology 9(4): 1-5

April 18, 1906: The Great San Francisco Earthquake

"San Andreas Fault
Moved its fingers
Through the ground
Terra cotta shattered
And the walls came
Tumbling down

O, promised land
O, wicked ground
Build a dream
Tear it down

O, promised land
What a wicked ground
Build a dream
Watch it all fall down"
"San Andreas Fault" sung by Natalie Merchant


One of the firsts to note something unusual where the sailors of the transport ship "Wellington" entering the bay in early morning of April 18. 1906, the captain reports that the ship "shivered and shook like a springless wagon on a corduroy road" even if the sea was as "smooth as glass".
At the shores of Ocean Beach the worker Clarence Judson was taking a swim in the sea when he was grabbed by a strong current and sucked into the deep - only with great effort he reached the coast:

"I tried to run to where my shoes, hat and bathrobe lay, but I guess I must have described all kinds of figures in the sand. I thought I was paralyzed. Then I thought of lightning, as the beach was full of phosphorescence. Every step I took left a brilliant iridescent streak. I jumped on my bathrobe to save me."

In Washington Street the police sergeant Jesse Cook observed a terrifying spectacle:

"The whole street was undulating. It was as if the waves of the ocean were coming toward me, billowing as they came..[]"
"Davis Street split right open in front of me, … A gaping trench. . . about six feet deep and half full of water suddenly yawned and sprang up on the sidewalk at the southeast corner while the walls of the building I had marked for my asylum began tottering. Before I could get into the shelter of the doorway those walls had actually fallen inward. But the stacked-up cases of produce that filled the place prevented them from wholly collapsing."

The Geography professor George Davidson awoke from the tumult coming from the street, he grabbed his wristwatch on the desk and noted the length of a first quake - 60 seconds- and the second - again 20 to 40 seconds - and the time that later will be the official date of the great earthquake of San Francisco: 5:12.

Many people were still asleep and killed in their beds, those who escaped gathered in the streets - despite the earthquake most of the city seemed still intact and surprisingly quiet.

In 1906 San Francisco was a great and ambitious, but also corrupt and infamous city with more than 400.000 inhabitants; it had experienced an incredible growth since 1848 thanks to the discovery of gold in the rivers of California. Now it was an important harbour to the Pacific Ocean and modern trade place, many shops sold the newest technologies in cameras and film equipment. The earthquake of San Francisco will become the first natural disaster of its magnitude to be so well documented by photography and motion picture footage (even in colour).
This growth and achievements were however possible only by cheap and fast construction methods and so most buildings in San Francisco were not exceptionally stable and made of wood.
San Francisco had burned to the ground six times in the past century and experienced stronger earthquakes in 1865 and 1868 when 30 people died. However the modern automatized fire department and equipment - horse driven and steam powered water pumps - was believed to be capable to fight every fire.
Fig.1. "Earthquakey Times", a caricature by Ed Jump of the October 8. 1865 earthquake in San Francisco. While he was working as a newspaper reporter in San Francisco, Mark Twain experienced the earthquake which he describes in his 1872 book "Roughing It."
"It was just after noon, on a bright October day. I was coming down Third Street. The only objects in motion anywhere . . . were a man in a buggy behind me, and a [horse-drawn] streetcar wending slowly up the cross street. . . . As I turned the corner, around a frame house, there was a great rattle and jar. . . . Before I could turn and seek the door, there came a terrific shock; the ground seemed to roll under me in waves, interrupted by a violent joggling up and down, and there was a heavy grinding noise as of brick houses rubbing together. I fell up against the frame house and hurt my elbow. . . A third and still severer shock came, and as I reeled about on the pavement trying to keep my footing, I saw a sight! The entire front of a tall fourstory brick building on Third Street sprung outward like a door and fell sprawling across the street, raising a great dust-like volume of smoke! And here came the buggy-overboard went the man, and in less time than I can tell it the vehicle was distributed in small fragments along three hundred yards of street. . . . The streetcar had stopped, the horses were rearing and plunging, the passengers were pouring out at both ends. . . . Every door, of every house, as far as the eye could reach, was vomiting a stream of human beings; and almost before one could execute a wink and begin another, there was a massed multitude of people stretching in endless procession down every street my position commanded. . . . For some days afterward, groups of eyeing and pointing men stood about many a building, looking at long zig-zag cracks that extended from the eaves to the ground..."

Police sergeant Jesse Cook was the first to report a fire at April 18. in a grocery in Clay Street, some hours later there where already fifty in the entire city. The fire fighters realized horrified that the water pipers in the underground were broken and the hydrants in the city useless. The firestorm rages in the city for three days and will be responsible of 90 percent of the 28.000 destroyed buildings.

The journalist Arnold Genthe is thrilled by the scenery and the devastation caused by the approaching fire, unfortunately he discovers that his camera was damaged during the quake.

"I found that my hand cameras had been so damaged by the falling plaster as to be rendered useless. I went to Montgomery Street to the shop of George Kahn, my dealer, and asked him to lend me a camera. "Take anything you want. This place is going to burn up anyway." I selected the best small camera, a 3A Kodak Special. I stuffed my pockets with films and started out...."
He will take some of the most famous photos in history.

Fig.2. "Looking Down Sacramento Street, San Francisco, April 18. 1906."

The owner of "Hotaling´s Whiskey" in Jackson Streets decides to remain and fight the flames - he pays 80 men to sprinkle 5.000 barrels of whisky with water pumped out from the sewer system. Later he will mock all those who claim that the earthquake was send by god by coining a new advertising slogan:

"If, as some say, God spanked the town, for being over frisky - why did He burn the churches down an save Hotaling´s Whiskey?"

Army troops were soon ordered into the city to help in the fire fighting and prevent panic and looting. The lack of water forced to desperate measures - by blasting of entire quarters to create firebreaks it was hoped to stop the flames, however many explosions ignited even more fires. Despite martial law was never proclaimed, the major authorized policeman and soldiers to shoot looting persons - "Obey orders or get shot" was the grim warning on some improvised signboards.
Guion Dewey, a businessman from Virginia, wandering onto the streets of downtown San Francisco minutes after the quake experienced the best and worst of human behavior, as he later reported in a letter to his mother:

"I saw innocent men shot down by the irresponsible militia. I walked four miles to have my jaw set. A stranger tried to make me accept a $10 gold piece. I was threatened with death for trying to help a small girl drag a trunk from a burning house, where her father and mother had been killed. A strange man gave me raw eggs and milk . . . (the first food I had had for twenty-two hours). I saw a soldier shoot a horse because its driver allowed it to drink at a fire hose which had burst. I had a Catholic priest kneel by me in the park as I lay on a bed of alfalfa hay, covered with a piece of carpet, and pray to the Holy Father for relief for my pain. . . . I saw a poor woman, barefoot, told to "Go to Hell and be glad for it" for asking for a glass of milk at a dairyman's wagon; she had in her arms a baby with its legs broken. I gave her a dollar and walked with her to the hospital. . . .I was pressed into service by an officer, who made me help to strike tents in front of the St. Francis Hotel, when the order was issued to dynamite all buildings in the vicinity to save the hotel. I like him, and hope to meet him again. When he saw I was hurt, which I had not told him, not yet having been bandaged, he took me to his own tent and gave me water and brandy and a clean handkerchief."

The earthquake and the firestorms killed estimated 3.000 to 4.000 people, destroyed 28.000 buildings and the infrastructure of the entire city - but in a surprisingly rush people begun planning and reconstruction work on their homes and life, three year later most of San Francisco was rebuild.

Seismology was still a young scientific discipline at the time of the earthquake in San Francisco, in part as a result of the lack of appropriate equipment like sensible tools to measure the tremors of earth - worldwide there were only 96 seismographs operating, none of these in California. In the aftermath of the disaster, only three days later, the Governor of California announced the formation of the State Earthquake Investigation Commission led by geologist Andrew C. Lawson of the University of California.
The commission concentrated their work on the San Andreas Rift, a local straight valley until them considered of minor interest and mapped only in short sections. For two years Lawson and his team followed the rift along ponds and streams and up and down poison oak-covered hills on foot and horseback, they recognized that the rift followed almost the entire coastline of California for more than 1.000 kilometres. During the April 18. earthquake nearly 480 kilometres of the Earth's surface along the today notorious known San Andreas fault line had ruptured displacing the ground horizontally instead of vertically, as geologists had previously believed to be the source of earthquakes.
The commission will locate the epicentre of the earthquake at the place of the greatest observed displacing on land - however today the epicentre is believed to be situated below the Pacific Ocean, in accordance to the seismic waves coming from the sea as observed by the first eyewitnesses.

Nevertheless this finding led team member Henry Fielding Reid, a geology professor at Johns Hopkins University in Maryland, to propose a new theory regarding the origin of earthquakes. Later dubbed the "theory of elastic rebound" Reid's hypothesis was to have a revolutionary impact on the young field of seismology.


MORRIS, C. (2006): The San Francisco Calamity by Earthquake and Fire. Librivox
SLAVICEK, L.C. (2008): The San Francisco Earthquake and Fire of 1906. Great Historic Disasters. Chelsea House Publishers: 128
STARR, J.D. (1907): The California Earthquake of 1906. A.M. Robertson, San Francisco

Online Resources:

USGS (2009): The Great 1906 San Francisco Earthquake.
(Accessed on 17.04.2011)

A geologist riddle #12

An easy georiddle this time, the searched event is not the depicted but a related, more notorious, one.

The landslide of Köfels: Geology between Pseudoscience and Pseudotachylite

The landslide of Köfels covers an area of at least 11,5 square kilometres with an estimated volume of 2 to 3 cubic kilometres, the largest landslide in the crystalline Alps. The landslide descended from the western slope of the valley, damming in transverse the Ötztal and branding against the opposite valley flank, this mass - the Tauferberg - blocked the mouth of the tributary valley of Hoarlach. The river of the Ötztal, the Ötztaler Ache, became dammed to a 7 kilometres long lake. In the basin of Längenfeld lake sediments have been drilled up to a thickness of 92m. Simultaneously the river has cut a deep gorge into the dam, the Maurach gorge is still today the only way trough the landslide barricade.
Pieces of wood recovered from a gallery driven in the Tauferberg during exploration work for a power station resulted in a conventional radiocarbon age of 8.710+/-150 years BP (ca. 9.800 years cal BP), this early Holocene age is supported by additional cosmogenic isotope dating of surface boulders that yielded an age of 8.889+/-490 to 10.630 +/-570 years BP.

Fig.1. View from north into the valley of Ötz and the landslide of Köfels, on left the Tauferberg with the village of Umhausen in the foreground. On the right the concave escarpment of the landslide that lowered the mountain by estimated 200 meters. Displaced rockslide masses enveloped by stippled dark line.

Fig.2. Geological map of the Köfels rockslide area with frictionites sites and (IA) Horlach valley, i.e. place of finding of C-14 dated wood fragments buried by the rockslide deposits. Displaced rockslide masses enveloped by stippled dark line (after PRAGER et al. 2009). The map is mirrored in reference to the previous photography.

The landslide of Köfels was recognized already by pioneer geologists mapping the Alps like Escher von der Linth in 1845 and the two great quaternary geologists Penck & Brückner in 1909. The Tyrolean geologist Klebelsberger describes the morphology of the landslide in his book "Geologie von Tirol" (1935):

"…the landslide slide down apparently from the western to south-western mountain ridge above Köfels… great gliding surfacse let recognize the movement of large masses of rocks. It seems that the ridge was considerably lowered by the collapse by estimated 200m."

Ironically it was the shear mass of the landslide that misdirected later authors, observing outcrops of not shattered gneiss inside the limits of the loose debris they underestimated significantly the volume of the entire landslide - it was not yet recognized that the upper part of a large landslide can glide like a single coherent mass.
According to the new estimated volume the landslide was considered be only superficial and to "thin" to explain the observed completely shattered rocks underlying it .
A second particularity observed at the landslide seemed to provide a possible alternative explanation:
The occurrence of rocks resembling pumice in the area has been of particular interest and has caused controversial discussions of the origin of the landslide since 1920, Klebelsberger continues:

"… a particular kind of formation, for which a volcanic origin or at least influence must be considered, like nowhere else in the interior of the Alps, are the deposits of pumice in the area surrounding of Köfels in the valley of Ötz… a local peculiarity… postglacial liparitic pumice. It is an in part yellow-grey to yellow-brown, sometimes light grey to dark grey, extraordinary foamy, mostly vesicular to in rare occasions fibrous rock, with common inclusions of mylonized gneiss."

Some authors interpreted the shattered rocks and the pumice as a diatrem or the roof of a magma chamber of a supposedly Post-glacial or Holocene volcanism in the Alps (the landslide incorporates glacial sediments). In 1936 other authors suggested that the rocks are the eroded remains of the ejecta of a Holocene meteorite impact. Both hypothesis however were contradicted by evidence in the field, the supposed ejecta-deposits were found only on one side of the mountain, not scattered around a supposed impact point or volcanic conduit (never found), and the pumice was uncovered by the landslide, not overlying it as expected from a rain of molten rocks after the impact.

Only since 1970 with research performed on very large landslides in the Alps and especially in the Himalaya it was realized that the apparently partially molten rock - referred as Frictionite, Pseudotachylite or Hyalomylonite - is the results of friction heat caused by the sliding of gigantic rock masses, a unique mechanisms still today poorly understand.
Despite this new evidence, curiously in 2008 the impact hypothesis was revived by some pseudoscientists in connection to supposed observations of a meteorite by the Sumerians or to explain the death of the Iceman as a human sacrifice to prevent a nuclear winter after the impact.

Fig.3. Part of the eastern slope of the Maurach gorge where the cutting of a road along the river Ötz has exposed the crushed lower strata of the slide with veins of Frictionite/Pseudotachylite/Hyalomylonite. The upper part of the Köfels landslide moved as a large semi-coherent mass, covered by loose debris.

Fig.4. Drawing of the microscopic view of a (tectonic) shear plane with pseudotachylite in gabbro (rock with pyroxene and feldspar - Fs) of Rhodos. In the grey homogenous mass of the glass (molten and then quickly resolidified) with a sharp contact to the unmodified rock weak flow structures (F) are recognizable and additionally fragments of the primary source rocks.

There is a third geological peculiarity of the landslide of Köfels: The village of Umhausen situated north of the landslide is since 1992 notoriously known for its high percentage of lung diseases and cancer of the local inhabitants.
The lung cancer increase was caused by the unusual high concentration of the radioactive gas Radon in buildings of the area. The presence of such amounts of Radon baffled experts, well above the natural values expected for the underground geology consisting of metamorphic ortho- and paragneiss. Both rocks contain very small quantities of Uranium, which decaying converts to Radon, but the amount of gas released is as the concentration of Uranium in the source rock itself very small. However the rocks of the landslide deposits, on which the village in part stands, are shattered until the single mineral grains, increasing exponentially the surface emanating Radon.


HERMANNS, R.L.; BILKRA, L.H.; NAUMANN, M.; NILSEN, B.; PANTHI, K.K.; STROMEYER, D. & LONGVA, O. (2006): Examples of multiple rock-slope collapses from Köfels (Ötz valley, Austria) and western Norway. Engineering Geology Vol. 83 (1-3): 94-108
HEUBERGER, H. (1966): Gletschergeschichtliche Untersuchungen in den Zentralalpen zwischen Sellrain- und Ötztal. Wissenschaftliche Alpenvereinshefte Nr. 20
HUSEN, D.v.; BORTENSCHLAGER, S.; DRAXLER, I.; DRESCHER, R.; FRANK, C.; HAVLICEK, P.; HOFFNANN, K.; NAGEL, D.; PATZELT, G.; POSCHER, RABEDER, G.; TYRACEK, J.; WALTL, R. & WANSA, S. (1995): Eastern Alps Traverse. In SCHIRMER W. (ed.): Quaternary field trips in Central Europe: 381-434
IVY-OCHS, S.; HEUBERGER, H.; KUBIK, P.W.; KERSCHNER, H.; BONANI, G.; FRANK, M. & SCHLUCHTER, C. (1998): The age of the Köfels event. Relative, 14C and cosmogenic isotope dating of an early Holocene landslide in the central Alps (Tyrol, Austria). Zeitschrift für Gletscherkunde und Glazialgeologie Vol. 34: 57-70
LAHODYNSKY, R.; LYONS, J.B. & OFFICER, C.B. (1993): Phänomen Köfels - eine nur mühsam akzeptierte Massenbewegung. Geologie des Oberinntaler Raumes - Schwerpunkt Blatt 144 Landeck. Arbeitstagung der Geologischen Bundesanstalt, Wien: 159-162
PRAGER, C.; ZANGERL, C. & NAGLER, T. (2009): Geological controls on slope deformations in the Köfels rockslide area (Tyrol, Austria). Austrian Journal of Earth Sciences Vol. 102(2): 4-19

15 April, 1912: The Iceberg That Sank the Titanic

In the night of April 14, 1912 the passenger liner "R.M.S. Titanic" collided with an iceberg, two hours later (2:20, April 15)  the ship sank, estimated 1490 to 1517 passengers died in the cold water of the Atlantic.
The story of the ship became part of history and pop culture, but the story of the iceberg that caused the disaster is less understand or known and only vague descriptions and some photos exists of the supposed iceberg(s).

Fig.1. The moment of the collision according to the sailor Frederick Fleet - one of the two men on duty as lookout in the night of April 14 (after EATON & HAAS 1986).

Fig.2. One of the many icebergs suspected of having sank the Titanic photographed in the morning of April 15, from board of the ship "Prinz Adalbert". The eyewitnesses still unaware of the disaster of the previous night reported a "red smear" at the waterline of the white giant still visible and therefore supposedly less than 12 hours old. The (contradicting) dimension of the iceberg given were 30 meter height and 100 meter width (photo from Wikipedia).

Fig.3. Another iceberg photographed April 20, from the German steamer "Bremen" claimed to be the Titanic iceberg based on the vicinity to the location of the disaster and the description of the iceberg according to e
yewitnesses reports of Titanic survivors (photo from Wikipedia).

Fig.4. Photography of an ice
berg from the cable ship "Minia", one of the first ships to reach the area in search for debris and bodies. The crew found debris and bodies floating in the vicinity of the depicted iceberg and the captain assured that this was the only iceberg near the scene of the collision (after Titanic & Nautical Resource Center).
 Fig.5. Journalist Colin Campbell, a passenger of the "Carpathia" - the first ship to approach the scene of the disaster and save the surviving passengers of the Titanic - described the iceberg for the New York Tribune (after EATON & HAAS 1986).

Fig.6. Photography from the ship "Birma" of the same iceberg as described by Campbell. This iceberg has some remarkable similarities to the iceberg as described and drawn by survivors of the Titanic (see the first figure with the drawing by Fleet).
Despite the question if one of the photos shows the culprit iceberg, the remarkably number of spotted icebergs emphasizes the notion that in 1912 an exceptional number of these white giants reached such southern latitudes (after EATON & HAAS 1986).

The icebergs from the North Atlantic originate mainly from the western coasts of Greenland, where ice streams deliver large quantities of ice in the fjord-systems which leads to the Baffin sea. Still today this region is the most important origin of icebergs on the northern hemisphere, thousands of junks of ice per year drop from the front of the glaciers and if large enough will one or three years later reach the North Atlantic.

Ironically it was in 1909, three years before the disaster, that the construction works for the Titanic begun in the dockyard of Harland & Wolff Ltd. in Belfast (Ireland).

When the large iceberg reached the cold open sea of the Baffin Bay the West Greenland Current pushed it first slowly to north
ern realms following the coast of Greenland, then along the Canadian coast the voyage to the south begun.
Finally offshore of Newfoundland the iceberg was captured by the "warm", but fast Gulf Stream and pushed in south-western direction. Only one percent of all icebergs reach such southern latitudes, in 1912 however icebergs were spotted remarkably often in this area, maybe as a result of previous mild winters and strong activity of the calving glaciers (discussed also in this post on
"The Science behind the Iceberg that sank the Titanic").

 Fig.7. Schematic diagram of marine currents (blue= cold; red = hot) around Greenland and the hypothetical region of origin (West Greenland) and route of the iceberg that collided with the Titanic.

The construction of the Titanic proceeded with astonishing rate; the ship was launched to the sea on May 31, 1911 and her outfitting was completed by March 31,  1912.
The ship began its maiden voyage from Southampton, and after a stop in the French Cherbourg and the Irish Queenstown, it set out the final route for New York City on April 10, 1912.

Four days later the Titanic encountered the anonymous iceberg. In the following days bypassing ships at the site of the disaster encountered and photographed various icebergs, some eyewitnesses claim to have spotted red paint on some of them, however there is no conclusive evidence that the culprit iceberg was spotted - and there will never be - at least two to three weeks later the iceberg that sank the Titanic would be melted and disappeared forever into the Atlantic Ocean.


EATON, J.P. & HAAS, C.A. (1986): Titanic Triumph and Tragedy. Haynes Publishing: 352
SOUTH, C. (2006): The Iceberg That Sank the Titanic. The Natural World documentary film – BBC


Fig.1. Daemonosaurus chauliodus (from Spiegel Online, 13.04.2011, credit by Jeffrey W. Martz).

The generic nomen is derived from Greek daimon, evil spirit, and Greek sauros, reptile, in allusion to legends about evil spirits at Ghost Ranch, New Mexico. The specific epithet is derived from Greek chauliodous, with prominent teeth.

With such a geomythological name the little fellow deserves a brief spot here on the blog...


SUES, H.D.; NESBITT, S.J.; BERMAN, D.S. & HENRICI, A.C. (2011): A late-surviving basal theropod dinosaur from the latest Triassic of North America. Proceedings of the Royal Society B: 1-6

12 April, 2010: The railway debris flow of South Tyrol

12. April 2010 South Tyrol: 9 confirmed victims, 23 people injured; this was the headline about a rail crash between the towns of Latsch and Kastelbell reported by the news almost worldwide.
The modern railway between the two localities follows the orographic right bank of the main river Etsch, the accident occurred at a segment inside a gorge eroded by the river in Holocene sediments (manly a large alluvial fan coming from south with unconsolidated debris-flow deposits).

At 9.02 in the morning, just when the train approached, a debris flow of 400 cubic meters - with a width of 10 to 15 meters and a thickness of 2m - bursted off 50m above the railway line and hit the first wagon, knocking it from the railway.

Fig.1. The derailed train during the difficult rescue efforts (SüdtirolNews).

To clarify possible causes of the landslide soon after geological investigations were initiated. Eye witnesses reported large quantities of water running down the slope after the accident. A preliminary site investigation by the authorities concluded that the leakage of an irrigation system above the location (the area is used for agriculture) saturated the soil and underlying sediments with water, causing a mudslide just in the moment the train passed. The irrigation system was in use since the previous week and at least for the last days or hour's large quantities of water infiltrated in the underlying slope and saturated the debris. It is possible that the vibrations of the approaching train triggered finally the fatal slide that initiated the debris flow.

Today, one year after the deadly debris flow, a memorial stone was inaugurated to remember the nine victims of the disaster.

In search of Lemuria

"Yet if hope has flown away
In a night, or in a day,
In a vision, or in none,
Is it therefore the less gone?
All that we see or seem
Is but a dream within a dream."
"A Dream Within A Dream" by Edgar Allan Poe (1809-1849)

With the census of life forms in the 19th century naturalists realized that many similar animal species were distributed on different continents or remote islands. For short distances this was explainable by (voluntary or involuntarily) migration on water, on islands or in the air, but many distances were too great to overcome by large animals, especially by mammals.
The English lawyer and zoologist Philip Lutley Sclater (1829-1913) noted the particular distribution pattern of a particular group of primates - the Lemurs. Sclater however included in his Lemuridae more species than modern systematic - the Lemurs, the Indri and the Aye-aye (found on Madagascar), the Galagos (found in Africa), the Loris (found in Asia) and the Tarsiers (found in Indonesia). He observed that "while 30 different species of Lemurs are found in
Madagascar alone, all of Africa contains some 11 or 12, while the Indian region has only 3." In a short essay of 1864 titled "The Mammals of Madagascar", published in the brand new "The Quarterly Journal of Science", he addressed the possible answer - Madagascar with it's rich diversity of species was the homeland of lemurs which spread all over Asia and Africa by a land bridge connecting once these continents. He named this supposed continent appropriately "Lemuria" and because of similarities with of the lemurs of Madagascar to new world monkeys he speculated even with a connection to America:

"The anomalies of the Mammal fauna of Madagascar can best be explained by supposing that anterior to the existence of Africa in its present shape, a large continent occupied parts of the Atlantic and Indian Oceans stretching out towards (what is now) America to the west, and to India and its islands on the east; that this continent was broken up into islands, of which some have became amalgamated with the present continent of Africa, and some, possibly, with what is now Asia; and that in Madagascar and the Mascarene Islands we have existing relics of this great continent, for which as the original focus of the "Stirps Lemurum," I should propose the name Lemuria!"

In later works he was more cautious:

"This fact would seem to show that the ancient "Lemuria", as the hypothetical continent which was originally the home of the Lemurs has been termed, must have extended across the Indian Ocean and the Indian Peninsula to the further side of the Bay of Bengal and over the great islands of the Indian Archipelago."
Page 236-237, SCLATER & SCLATER (1899): "The Geography of

Sclater was not the first to promote ancient land bridges or even a sunken continent in the Indian Ocean, the idea of oceans as drown landmasses was a plausible geological theory at the time.
Marine fossils found on land demonstrated that sea level changed over time, land became sea and even if the exact mechanism was unknown, it was not impossible to image that also land would become sea.
The French geologist Etienne Geoffrey Saint-Hilaire had speculated about a connection between Madagascar and India in 1840, the English geologist Searles V. Wood (1830-1884) hypothesized the existence of a giant southern continent during the "secondary era" (modern Mesozoic). Alfred R. Wallace (1823-1913), biogeographer of South America and Indonesia, proposed in 1859 a sunken continent to explain the f
auna found on Celebes, but became later one of the most eloquent critic of the theory.
The theory of Lemuria was interesting speculation but even Sclater mention it only as idea and never promoted it too much.

In 1868 the German biologist Ernst Haeckel published his German edition of "Natürliche Schöpfungsgeschichte"(The history of Creation), addressed to
a general public where he promoted his view of evolution of life and humans. Haeckel considered the earliest humans descending from Asian primates and placed the cradle of humanity in Asia or in alternative Africa and very cautiously on the hypothetical continent between these landmasses. Lemuria played a major role as possible migration route of humans into Africa and Indonesia (Natürliche Schöpfungsgeschichte, page 515).
In later editions and the English version of the book, translated by Ray Lankester in 1876, the supposed continent is even emphasised and labelled in the map as "Paradise" and display
ed as cradle of humanity.

"The primeval home, or the "Centre of Creation", of the Malays must be looked for in the south-eastern par
t of the Asiatic continent, or possibly in the more extensive continent which existed at the time when further India was directly connected with the Sunda Archipelago and eastern Lemuria."
Page 329, HAECKEL (1876): "The history of Creation."

Fig.2. and 3. Ernst Haeckel, "A hypothetical sketch of the monophyletic origin and extension of the twelve races of Man from Lemuria over Earth." From Haeckel, Natürliche Schöpfungsgeschichte, Plate XV. Note the differences in the German version (1868) without Lemuria and the English version (1876) with Lemuria, after 1870 Haeckel adopted and promoted the idea of a sunken continent in the Indian Ocean.

"The probable primeval home or "Paradise" is here assumed to be Lemuria, a tropical continent at present lying below the level of the Indian Ocean, the former existence of which in the tertiary period seems very probable from numerous facts in animal and vegetable geography. But it is also very possible that the hypothetical "cradle of the human race" lay further to the east (in Hindostan or Further India), or further to the west (in eastern Africa)."
HAECKEL in 1870.

Haeckels work, as vague at is was, however spread the idea of sunken continents to a larger public, still in 1919 the English author Herbert George Wells wrote:

"We do not know yet the region in which the ancestors of the brownish Neolithic peoples worked their way up from the Palaeolithic stage of human development. Probably it was somewhere about south-western Asia, or in some region now submerged beneath the Mediterranean Sea or the Indian Ocean, that, while the Neanderthal men still lived their hard lives in the bleak climate of a glaciated Europe, the ancestors, of the white men developed the rude arts of their Later Palaeolithic period."

WELLS (1919): "Outline of History.

The idea of Lemura as lost cradle of humankind proposed (however not too actively supported) by serious scientists was to fascinating for pseudoscientific and esoteric groups and authors not to be incorporated in their worldview.
In 1888 the Russian esoteric author Elena Petrovna Blavatskaja (1831-1891), strongly influenced by Asian philosophy, published her "The secret doctrine" in which she proposes Lemuria as the cradle of one of the seven root races of humanity. These beings supposedly possessed four arms and eyes and were egg-laying hermaphrodites and shared the continent Lemuria with dinosaurs. The never existed continent of Lemuria became part of popular culture.


RAMASWAMY, S. (2004): The lost land of Lemuria - Fabulous geographies, catastrophic histories. University of California Press: 334

Online Resources:

FREISTETTER, F. (04.04.2011): Lemuria: wenn Wissenschaft zu Esoterik wird. (Accessed on 07.04.2011)

6 April, 2009: L'Aquila Earthquake

At 3:32 in the morning a 20 seconds lasting earthquake with magnitude 6,9 (followed quite until midday by weaker aftershocks) occurred 7km near the city of Aquila, the capital of Abruzzo, within a depth of 8,8km.

Fig.1. Intensity map of Central Italy Earthquake 2009-04-06 (L'Aquila) from the USGS.

More than 45 towns were affected, 308 people killed, 1.600 injured and more then 65.000 inhabitants were forced to leave their houses.

Italy has a long and tragic history of earthquakes. The setting between to larger continental plates (the European and African) and various micro plates results in a highly active tectonics all over the peninsula.
The first map of seismicity of the Mediterranean area and an extensive research on earthquakes in Italy was published in 1857 by the Irish engineer - and self educated geologist - Robert Mallet under the title "Great Neapolitan Earthquake- The First Principles of Observational Seismology". Mallet got interested in earthquakes in 1830 by a drawing in a natural science book displaying two columns twisted by an earthquake in Calabria. He decided to study the forces able to do this to human constructions. In his work he noted that damages on constructions were distributed in distinct areas, setting out from a point of heaviest havoc. These points, the epicentre of an earthquake, were not randomly distributed, but found in "seismic belts" following the Apennines.

Earthquakes mark the history of the region surrounding L'Aquila and the province of Abruzzo, historic events or swarms of trembles are recorded from 1315, 1349, 1452, 1461, 1498, 1501, 1646, 1703, 1706, 1791, 1809, 1848 and 1887, one of the most important on the 2, February of 1703 which caused devastation across much of central Italy and largely destroyed the city of L'Aquila and killed 5.000 people.

The destruction caused by the earthquake of 2009 surprised experts and generated discussions about the antiseismic building standards adopted in Italy. While most of the medieval structures in rural areas collapsed or were heavily damaged, in L'Aquila most concern arouse the observation that the modern buildings suffered the greatest damage and that the death toll included mostly young people. L'Aquila was a university town and cheaper accommodations which suffered severe damage were inhabited by students, also many students died when a dormitory at the University of L'Aquila collapsed. Even some buildings that were believed to be "earthquake-proof" were damaged, like parts of the new hospital and various buildings of the government.
In rural areas the "core" of most of the historic houses consisted of local material, like stone, superimposed by cement constructions or supplementary storeys of modern age. It was this mismatch that caused the collapse of many buildings. In L'Aquila the earthquake of 1703 destroyed most of the ancient buildings, during reconstruction work first antiseismic regulations were introduced - the rebuild houses possessed thicker walls, improved joints between floors and the allowed height of the building was limited. Most "modern" buildings in contrast were build previously of 1984, before modern antiseismic buildings standards were introduced in Italy.
However there was and still is a widespread disregard of building standards and the ignorance by people and (in part corrupt) authorities of the seismic hazards. Many concrete elements of the collapsed buildings (like the hospital) "seemed to have been made poorly, possibly with sand" a common tactic to build fast and cheap by building enterprises controlled by criminal organisations.
The earthquake of L'Aquila was therefore only in part a natural disaster and the manmade catastrophe was strongly misused by Italian politics and economy and many promises are still unrealized today.

Fig.2. The local prefecture (a government office) damaged by the earthquake, emblem of the situation in Italy, from Wikipedia.

However most alarming were the legal repercussions of the earthquake on science. Based on a general lack of understanding of science by the public and authorities various persons were accused to have ignored "premonitory signs" of the earthquake and early warnings- pseudoscientific "premonitory signs" of dubious veracity and warnings mostly published by individuals in internet.

To cite what the geographer Grove Karl Gilbert (who studied intensively the earthquake in San Francisco of 1906) resumed during a meeting of the American Association of Geographers (AAG) in 1909 about the predictability of earthquakes:

"Common people would be satisfied to know if we reached the point where a scientific predictability for an imminent earthquake is possible."

But Gilbert criticised the simple belief that earthquakes automatically occur in cycles or after long periods of quiescence and that an extrapolation based only on historical records is possible.

"Considering the complexity of conditions and the chaotic interrelationships between underground tensions, it can not be assumed that the particular conditions of every epoch will repeat always at the same manner."

Gilbert concluded that we should not try to predict specific events, but to prepare for the general hazard:

"[seismologists should not]…try to enforce control on the course of nature, but with the support of science, predict the imminent changes, so to enable the people to be warned and to be prepared…[]. The determination of the instant of seismic hazard belongs to an indefinite future. It is still a realm of try and hope."


TERTULLIANI, A. (2011): Il segni del terremoto sul tessuto urbano. DARWIN No. 42 Marzo/Aprile: 80-83
WALKER, B. (1982): Earthquake. Planet Earth. Time Life Books: 154