Anniversary of the Zagreb earthquake – an opportunity to look into the past
Anniversary of the Zagreb earthquake – an opportunity to look into the past
A look into the past
What Kišpatić wrote about earthquakes back in 1880
On this day one year ago, we were struck by a devastating earthquake. The memory of that day is an opportunity to look into the past and see what Mijo Kišpatić wrote about earthquakes in his book “Images from Geology”, published in 1880.
It is interesting to note that, in that very year of 1880, the inhabitants of Zagreb were awakened early in the morning on 9 November by a devastating earthquake. After 140 years, history seemed to repeat itself when an earthquake of magnitude 5.3 on the Richter scale “wished” Zagreb good morning on Sunday, 22 March, at 06:24.
Let us now look at several interesting excerpts from Kišpatić’s chapter on earthquakes.
Although Kišpatić himself says: “And what does the learned world today know about the origin of earthquakes? Very little, but at least it knows that there is much about earthquakes that it cannot explain.”, his text contains an abundance of valuable data and observations, vivid descriptions of damage and accompanying natural phenomena, as well as attempts to explain the causes of earthquakes in which connections with today’s knowledge can already be seen.
“… But when the earth suddenly begins to shake, something enters this dead crust and brings it to life. Our faith suddenly betrays us. Every sound, every vibration of the air affects us. A person, so to speak, no longer trusts even the ground on which he walks. This unusual state fills the animal world with restlessness and fear. Dogs and pigs are the first to become disturbed. Crocodiles in the Orinoco, otherwise silent animals like our lizards, leave the moving riverbed and flee howling into the forest.
With such impressions, it is no wonder that people have always been interested in the question of where earthquakes come from and what kind of force produces such unusual phenomena from within our Earth. Pagan peoples regarded earthquakes as divine punishment and attributed them to one god or another. Roman priests established holidays during earthquakes…
Peruvians say that their god sometimes rises from his seat and that with every step he takes the earth trembles. He does this, they say, to count the people on Earth, because from the rumbling he knows how many people there are. That is why Peruvians, at even the smallest earthquake, run out of their huts and begin jumping, banging and shouting: here we are, here we are!…
And what does the learned world today know about the origin of earthquakes? Very little, but at least it knows that there is much about earthquakes that it cannot explain. Therefore, certain individuals have now begun to carefully collect reports about earthquakes, because only in this way will they be able to trace the true cause of earthquakes.
It is usually assumed that there are three types of earthquakes. The first type is a vertical earthquake, where the ground suddenly rises and falls; the second type is where the ground moves in waves; while in the third type the ground, so to speak, moves in a circle.
Stronger earthquakes quite often produce significant changes on the Earth’s surface through their powerful movement. When the Earth’s crust begins to bend more strongly, it is natural that it cracks somewhere on the surface or inside. It often happens that after an earthquake streams dry up or new ones appear. In 1867 and 1877, earthquakes were felt three times in the area around Ogulin, and each time the nearby Kibnik spring dried up for a short time, … Enormous cracks appeared during the mentioned earthquake in Riobamba. Many people, horses and entire caravans of mules fell into the cracks on that occasion…
During strong earthquakes in coastal regions, it has been observed that the sea also becomes disturbed and turbulent. It suddenly withdraws far back from the coast. Entire parts of the seabed remain dry. After some time, the water begins to return in huge waves and penetrates far inland with great force… In 1690, during the earthquake near Pisca, the sea withdrew two miles and only returned after three hours. For populated coasts, this movement is much more dangerous than the earthquake itself. The water strikes the shore with terrible force, destroys and tears everything apart, and carries the ruins, together with people, back into the sea.
… In some regions people believe that earthquakes return regularly. In Canada, they expect an earthquake every 25 years, lasting 40 days. In Chile, they expect strong earthquakes every 23 years. There, the city of Copiapó was destroyed by earthquakes three times, always after 23 years, in 1773, 1796 and 1819, although the city suffered several times in between as well. There have always been people who imagined that they could predict in advance when an earthquake would occur. But these were always only simple superstitions.
It is certain that there are many cavities in the ground that water has washed out over time. It is quite natural that these cavities can sometimes collapse and thereby produce rumbling and shaking of the ground. For some weaker earthquakes in areas where mines have been excavated, it has been proven that they occurred in this way. However, the greatest part of earthquakes could not have originated in this way.
One part of earthquakes is volcanic in nature… These occur just before a volcanic eruption and sooner or later subside.
… Volcanic force is not always connected with earthquakes. Earthquakes occur in all parts of the world, both where there are volcanoes and where there are none. In the past, volcanic force was believed to have created mountains, but today it is known that mountains were formed differently. And it is precisely in the formation of mountains that the cause of earthquakes is sought today.
Mountains were formed by certain parts of the Earth’s crust contracting, folding and piling up. Even today, something is still contracting the surface of the Earth; it is still bending and folding somewhat. Through this bending, layers must sometimes crack on the lower bent part, and this is thought to cause many earthquakes…”
At the end of the chapter on earthquakes, Kišpatić notes: “There are still other views on the origin of earthquakes, but I cannot list them here, because that is not my purpose.”
Prepared by Biserka Radanović-Gužvica.