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3.6
weak
EARTHQUAKE DETAILS

M3.6 earthquake · 2 km North-West of Pollenza (MC)

3 years ago · 21 Feb 2023, 01:07

A weak earthquake, felt by some of the population. At only a few km deep the shaking is felt more sharply at the surface.

No. 4 of the month in ItalyStronger than 99% of Italian events in the past yearNo. 2 of the year in Marche

Where

2 km North-West of PollenzaEarthquakes in the province of MacerataEarthquakes in Marche

How far away could it be felt?

An estimate of how far people may have felt this quake.

  • up to ~8 km · felt by many people, especially on upper floors
    ≈ 37,000 people live in this area
  • up to ~27 km · felt only by some, at rest
    ≈ 386,000 people live in this area

The coloured rings on the map below show these distances.

Statistical estimate from the Italian intensity attenuation model (INGV): actual perception depends on geology, buildings and depth. Very shallow events can be felt locally even below the threshold.

Earthquake map

61 events
Magnitude:lightweakmoderatestrong

The energy released

How much energy this quake unleashed, translated into everyday comparisons.

3.8tof TNT equivalent
16 lightning bolts
M3
×7.9 the energy of a magnitude 3 earthquake
M3this quakeM5

Each extra magnitude unit releases about 32 times more energy: an M5 is not "a bit stronger" than an M4 — it is a different league.

Energy estimated with the standard Gutenberg–Richter relation; an average lightning bolt ≈ 1 billion joules. Indicative values.

The race of the seismic waves

Two waves set off from the hypocentre: the faster P wave arrives first with a sharp jolt; the S wave carries the actual shaking.

P waves — the first sharp jolt (~6 km/s)S waves — the strongest shaking (~3.5 km/s)
t ≈ 22 s

Animation sped up ~4× compared to reality.

  • Ancona
    36 km from the epicentre
    first tremor in ~6 s
    main shaking in ~10 s
  • Foligno
    55 km from the epicentre
    first tremor in ~9 s
    main shaking in ~16 s
  • Fano
    66 km from the epicentre
    first tremor in ~11 s
    main shaking in ~19 s
  • Teramo
    75 km from the epicentre
    first tremor in ~13 s
    main shaking in ~22 s

Theoretical times with average crustal speeds: real values vary with geology. The gap between P and S waves is what earthquake early-warning systems rely on.

How deep it was born

7 km
shallow

At only a few km deep the shaking is felt more sharply at the surface.

in line with the area average (~10 km)

For the same magnitude, a shallow earthquake is felt much more than a deep one: the energy starts closer to the surface.

What kind of quake is this?

Mainshock

It is the strongest quake of its sequence: so far it has been followed by 107 aftershocks within 30 km. Aftershocks tend to fade in number and strength over time.

Activity in the area right now (30 km radius)
0
last 24 hours
8
last 7 days
58
last 30 days
55 before107 after
this quake
Strongest of the sequence3.2

How often does it happen here?

about every ~37 days

Within 50 km of this epicentre, a magnitude ≥ 3.5 earthquake has occurred on average this often: 115 events in the last 12 years of the INGV catalogue.

An average computed on the recent past: it tells how used this area is to shaking, not when the next quake will come — earthquakes cannot be predicted.

The great earthquakes in this area's history

Almost a thousand years of catalogues: the strongest documented events within ~50 km.

17516.4
Appennino umbro-marchigiano earthquake
27 July 1751 · 49 km from here
XCompletely destructive: most buildings are destroyed.
12796.2
Appennino umbro-marchigiano earthquake
30 April 1279 · 43 km from here
XCompletely destructive: most buildings are destroyed.
17996.2
Appennino marchigiano earthquake
28 July 1799 · 18 km from here
IX-XCompletely destructive: most buildings are destroyed.
17416.2
Fabrianese earthquake
24 April 1741 · 32 km from here
IXDestructive: many buildings partly or fully collapse.

Source: Parametric Catalogue of Italian Earthquakes CPTI15 (INGV, CC BY 4.0).

The closest seismic structure

Southern Marche

The epicentre lies about 3 km from Southern Marche, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 6.9between 4 and 11 km deep

Faults are mapped to build better and understand the territory: knowing them says nothing about when an earthquake will occur, which remains unpredictable. Source: DISS 3.3 (INGV, CC BY 4.0).

Other quakes in the area

1.2
3 years ago
21 Feb 2023, 01:12
0.7
3 km North-West of Pollenza
1 km North-West · 10 km
3 years ago
21 Feb 2023, 01:14
0.8
3 km South of Treia
2 km North · 9 km
3 years ago
21 Feb 2023, 01:19
0.9
3 years ago
21 Feb 2023, 01:33
0.7
3 years ago
21 Feb 2023, 01:40
0.8
3 years ago
21 Feb 2023, 01:40
0.9
3 years ago
21 Feb 2023, 01:47
0.7
3 km South of Treia
2 km North · 10 km
3 years ago
21 Feb 2023, 01:57
0.3
4 km West of Pollenza
2 km West · 8 km
3 years ago
21 Feb 2023, 01:59
1.2
3 years ago
21 Feb 2023, 02:02

Data: INGV — National Institute of Geophysics and Volcanology (CC-BY 4.0)

Estimates computed by Meteare on INGV data (Gutenberg–Richter relation; Italian macroseismic intensity attenuation model).