The Phlegraean Fields supervolcano shook the region around the port city of Pozzuoli with a powerful earthquake swarm.
Pozzuoli – In recent weeks, the supervolcano to the west of Naples has been in the south of Italy been relatively quiet. In September it terrorized the approximately 350,000 residents in the Bay of Pozzuoli with over 1,100 tremors; the strongest tremor had a magnitude of 4.2 on the Richter scale. Parts of the facade fell onto the streets. At its peak, the earth shook 160 times within 24 hours.
After a break, Italy’s most dangerous volcano is becoming active again
In October the supervolcano suddenly strangely quiet. But on Sunday (October 15th) the supervolcano returned with two earthquakes measuring 1.45 and 1.9, An earthquake followed on Monday magnitude 3.6. But that wasn’t all: on Thursday night (October 19th), the earth shook 13 times between 7:32 p.m. and 6:05 a.m. Eight of the shocks were above level one on the Richter scale, with the strongest quake at 6:01 a.m. having a magnitude of 2.2.
Twelve of the quakes occurred between 5:24 a.m. and 6:05 a.m. – a classic swarm earthquake. This indicates volcanic activity underground. Magma, gas or heated water rises and sets the rocky ground in motion. In fact, many locals fear that the quakes are harbingers of an eruption of the supervolcano, which has had devastating effects in the past.
Supervolcano terrorizes region in Italy: Locals consider moving from Pozzuoli
People in Pozzuoli and the neighboring Neapolitan district of Bagnoli are at their wits’ end: “I’m seriously considering leaving Pozzuoli, I haven’t slept peacefully since August,” writes a user in the Facebook group “Those in the Red Zone of the Phlegraean Fields”. Another responds: “If you have the opportunity, do it.” A woman writes sarcastically: “Three nice shocks, yeah, what a nice wake-up call!” The epicenter of the swarm quake was once again at the Solfatara crater, which is known for its hot springs and steam geysers.
What many locals noticed again: Many of them first heard a rumble of thunder before they felt the actual quake. “The ground behaves like a huge loudspeaker that moves under our feet and transmits the vibrations to the air and thus to the atmosphere,” explains geologist Pietro Bongiorno of the phenomenon on the site geopop.it.
First a mighty thunder – and then the earth shakes
This perception of thunder before feeling the shock waves of an observation is explained by Bongiorno due to the different speed of propagation of seismic waves: “The first waves that arrive and are felt are the longitudinal (“first” P waves), they are the most difficult to vibrate But they can generate an acoustic signal.” According to the geologist, the noticeable waves are transverse waves, also called “S” waves. Bongiorno: “They are usually slower than the P waves.”