National Cat Day.
Is it true that they feel earthquakes first?
Predicting the arrival of an earthquake would be an incredible feat and could save many lives.
Over time, many beliefs have spread that animals, especially cats, could warn earthquakes early. But is it true that these animals can predict seismic events?
Today, February 17, National Cat Day, we celebrate the elegant feline and life partner of man, trying to answer this question.
According to the hypothesis of experts, cats have a special sensitivity to the Earth's magnetic fields and are able to feel minimal tremors, not perceptible to humans, which occur just before an earthquake of greater intensity.
Helmut Tributsch, a German scientist, conducted a study on the correlation between animal behavior and earthquakes published in the book 'The Prophets of the Earthquake' of 1900, in which he argued that animals could detect a flow of ions - electrically charged air - created by friction of the Earth's underground plates that rub together just before the occurrence of an earthquake, since they have drier body surfaces than humans, therefore more sensitive to electrostatic charges that precede seismic events.
Another research, conducted by US geologist Jim Berkland in the late 80s and early 90s, made it possible to predict two earthquakes in California by tracking advertisements of lost pets, especially cats, in newspapers. Berkland's theory was that cats who knew in advance that an earthquake would occur and would run away from home to escape the catastrophe, although there was no scientific evidence to support this hypothesis.
Do cats really feel earthquakes early?
In June 2018, a video which documents the strange behavior of a community of cats that used to be at the Cat Café in Osaka, in Japan.
In the video you can see many felines that at any moment start to move at the same time, as if something had frightened them: some raise their heads with a snap, others get up on their feet or move around the room. About ten seconds later the room begins to shake strongly, the chandeliers and some furniture sway, rattling noises are heard. It is an earthquake that has just hit the city of Osaka.
What scared the cats even before the earthquake? Did they notice any precursor phenomena of the seismic event?
The blog ingvterremoti.com has studied the case to try to give an answer to this question, through a mathematical calculation, which we report below.
Looking at the video we notice that the cats raise their heads and start moving at 07:58:48. The earthquake originated at 07:58:35, 13 seconds earlier. Cats raise their heads exactly in correspondence with a sharp noise in the room; it could therefore have been a simple sudden noise to have alerted them, but in reality we see that they continue to remain alert even during the following seconds.
Could it be that the cats heard the P waves?
P (Primary) waves are compression waves, also called longitudinal waves or primary waves. They are the fastest among the waves generated by an earthquake and therefore the first that are felt by a seismic station.
Here is the calculation that can be done: we have a P wave after 13 seconds and an S after 23 seconds from the time originating from the earthquake. If we assume an average speed of the P waves in the crust equal to 6 km / s we obtain a distance from the hypocenter of 78 km (6 km / sx 13 s).
Let's see the S waves: assuming a speed of the S waves equal to that of the P waves divided by 1.78 (as per the textbook) we get: 6 / 1.78 = 3.37 km / s. Multiplying this speed by the travel time (in this case 23 seconds) we get: 3.37 km / sx 23 s = 77.5 km.
P waves (primary, longitudinal) and S waves (transverse).
The two moments of "attention" of the cats could correspond to the arrival of the P waves and the S waves. Since the distance between the Cat Café and the epicenter of the earthquake is 77.5 kilometers, we can therefore believe that the cats were initially frightened because they felt the P wave of the earthquake, which took about 13 seconds to reach the Cat Café.
Whether the cats were really alarmed by the vibrations or the noise produced by something that was moved by the arrival of the seismic wave, we cannot know, as we cannot say with certainty that they are able to sense P waves or even warn the earthquake in advance. What is certain is that these beautiful animals must be loved, celebrated and respected every day for all the affection they are able to give us.
Source: INGV earthquakes
