Why Have There Been So Many Tremors In The Campi Flegrei In The Last 3 Months There's No Need To Be Alarmed
In recent months we are witnessing an increase in tremors in the Campi Flegrei, but what do they depend on? Earthquakes in the Phlegrean area are linked to the bradyseismic phase of ground elevation.
Earthquakes in Campi Flegrei , the active volcanic area located in the Gulf of Pozzuoli, north-west of Naples , have been on the rise for several months . The last shock clearly felt by the residents was recorded yesterday at 9:44 am , with a magnitude of 2.5 on the Richter scale , a depth of about 3 km and with its epicenter north of Pozzuoli . To have an even clearer idea of the situation, a particularly intense increase has been recorded in the last 3 months and it has gone from 283 earthquakes in October, to 365 in November up to 517of December.
Does this increase in seismic activity mean that Campi Flegrei is about to erupt? For the moment there is no cause for alarm : these tremors are nothing more than the result of bradyseism, a natural phenomenon typical of the area.
What happens to Campi Flegrei
Bradyseism , also known as "volcanic respiration", is a phenomenon which involves the periodic raising and lowering of the ground in correspondence with the Campi Flegrei caldera area: we are talking about an area approximately 180-200 km 2 wide . Why does this happen? There is no single theory but let's say that at the moment the most accredited causes concern:
- the volume change of a shallow magma chamber ( D'Auria et al., 2012 );
- the warming (and consequent expansion) of surface aquifers ( Chiodini et al., 2003 );
- the loss of CO 2 in the presence of fluids at very high pressures and temperatures ( Vanorio et al., 2015 ).
During the uplift phases, the formation of numerous low-magnitude earthquakes is frequent . Sometimes it is possible that these tremors become quite intense: in this case we speak of bradyseismic crisis , such as those that occurred in 1969-72 (upslope of the ground of 1.77 m) and in 1982-84 (upsurge of 1.78 m).
Data on the shocks of Campi Flegrei
Now that we have had a brief overview of bradyseism, let's take a detailed look at what has been happening in Campi Flegrei in recent weeks .
the whole area is in a phase of ground uplift .
Since January 2011, an uplift of about 96.5 cm has been recorded , of which 12.5 cm only since January 2022. This uplift is responsible for the formation of numerous low-intensity earthquakes, with a magnitude of less than 3.0 . More in detail, if we take the data for December 2022, of the 517 earthquakes recorded:
- 96 % (495 events) had a magnitude of less than 1.0 or could not be determined ;
- 3 % (17 events) had magnitude between 1.0 and 1.9 ;
- 1 % (5 events) had magnitude greater than or equal to 2.0 .
The maximum magnitude recorded is instead equal to 2.7 , therefore an earthquake that can be felt but which does not create particular damage or inconvenience to the population. Also from the geochemical point of view, the data confirm a multi-year trend of heating and pressurization of the hydrothermal system of the area typical of bradyseismic uplift phases.
At the moment, therefore, there is nothing to worry about and everything falls within the normal framework of the raising and lowering of the volcanic caldera: INGV itself reports in its bulletins that this trend is no different from those previously recorded. Is a bradyseismic crisis or an eruption coming? This cannot be predicted so far in advance and, precisely for this reason, it is essential to always stay up to date with all the information provided by INGV and the Civil Protection.
Why do people feel earthquakes even if they aren't that strong?
It's true, the tremors all have a rather low Richter magnitude , but that doesn't mean they can't be felt by the population . Indeed, if we take a look, the tremors often have an intensity on the Mercalli MCS scale between grade II and IV , i.e. they correspond to tremors that can be distinctly felt even inside one's own homes .
