After the seismic swarms that occurred in recent days in the Flegrei fields and in Calabria, some people have reported the experience of perceiving earthquake shocks also in their absence: this phenomenon takes the name of “Ghost earthquake” and is described as one false perception of an earthquake in the absence of seismic activity detected by the monitoring systems. Who is hit by this tactile hallucination – which in some ways remember the so -called “Ghost vibration” In which it happens to warn the smartphone to vibrate in the pocket when in reality it is not happening – it reports to warn soil tremolii or to perceive oscillations of objects and walls, accompanied by a sensation of prolonged anxiety, insomnia and strong concern. The phenomenon was clinically documented for the first time only in 2020so it is still largely unknown and its causes are still unknown. However, it seems to have one transitory naturegradually disappearing in the months following the end of a seismic swarm.
The first cases of “ghost earthquake” during the earthquakes of Zagreb of 2020
The phenomenon of the “ghost earthquake” was registered clinically for the first time following the sequence of earthquakes that hit Zagreb and the areas surrounding on March 22, 2020. That day, a few hours later the region was shaken by two earthquakes of magnitude 5.5 and 4.9followed by 125 minor shocks in the following weeks. Despite the significant damage to houses and infrastructures, 27 wounded were recorded and no victims due to collapses.
However, the seismic sequence caused a strong alarm in the populationfrightened by the possibility of an imminent tragedy, so much so that the Zagreb clinical hospital activated a telephone psychological support service for the population, recording a increase in cases of a phenomenon Until then never analyzed in the scientific literature. Specifically, many people reported to perceive suddenly and uncontrolled way vibrations and tremolii of the soil, warning a sort of “hallucination“In the absence of recorded activities, accompanied by a growing state of alarm and an intense anxiety. This phenomenon was called”ghost earthquake “.
The main characteristics of the “ghost earthquake”: the events
Thanks to the reports of patients, clinicians managed to describe in detail the phenomenon, which manifests itself mainly with the following characteristics.
- Illusory perception Of Power trees and vibrations, movement of objects, oscillation of walls and furniture in the absence of competing seismic events. These sensations suddenly appear both during the day and during the night, sometimes causing sudden awakenings.
- Psychological discomfort Characterized by sensations of anxiety, insomnia, panic, fear of crazy, confusion and persistent concern for the absence of confirmation of a real seismic event.
- Excessive alarm responses to environmental noisesstate of constant alert towards earthquake (such as obsessive control of seismic detectors).
- Changes in daily habitsincluding avoidance of prolonged or difficult to interrupt domestic activities in case of a seismic event (for example taking a shower or being on the balcony), preferring short and easily abandonable activities.
- In the most serious cases, feeling of nausea (a condition similar to the kinetosis but without a real movement), but also Dizziness and motor instabilitysometimes responsible for sudden falls.
In the case of the earthquakes of Zagreb, these symptoms they gradually attenuate themselves with the restoration of normality: during the first week following the earthquake the frequency of episodes varied from 1-5 times a weekgradually decreasing within 1-3 months.
The causes of the “ghost earthquake”: the hypothesis of the amygdala
The reason why the brain lets itself be “deceived” by stageing the illusion of the ghost earthquake It is not yet known. Although there are no specific scientific studies on the phenomenon, one of the hypotheses is that repeated earthquake shocks can leave the brain in a constant alert state, making it hypersensitive to environmental stimuli and sending false signals to our upper centers. From a neurobiological point of view, it is assumed that the structure mainly involved is the control unit of brain emotions: theamigdala. This region performs the delicate task of receiving and integrating all the environmental signals that we collect through the meaning bodies e assign them an emotion comparing them with our past experiences. All this happens very quickly e without rational control.
In the case of repeated seismic shocks, the state of general alert to which it has undergone could determine an hyperactivation of the amygdalainducing the brain to associate unconsciously even minimal vibrations or environmental variations to the experience of the earthquake, generating the illusory perception of a new seismic event, or the phenomenon of “Ghost earthquake”.
