All earthquakes
3.2
weak
EARTHQUAKE DETAILS

2 km South-East of Visso

111 months ago · 20 Apr, 11:48

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

Stronger than 98% of Italian events in the past yearNo. 5 of the year in Marche

Where

2 km South-East of VissoEarthquakes 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 ~15 km · felt only by some, at rest
    ≈ 6,000 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.

952kgof TNT equivalent
4.0 lightning bolts
M3
×2 the energy of a magnitude 3 earthquake
M2this quakeM4

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 ≈ 18 s

Animation sped up ~3× compared to reality.

  • Foligno
    24 km from the epicentre
    first tremor in ~4 s
    main shaking in ~7 s
  • Terni
    53 km from the epicentre
    first tremor in ~9 s
    main shaking in ~15 s
  • Teramo
    58 km from the epicentre
    first tremor in ~10 s
    main shaking in ~17 s
  • Perugia
    64 km from the epicentre
    first tremor in ~11 s
    main shaking in ~18 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

8 km
shallow

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

in line with the area average (~11 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?

Foreshock

In hindsight it was a foreshock: 111 months ago the same area had a stronger quake (M4.0). This can only be said after the fact — it was not predictable beforehand.

4.0
The mainshock
3 km West of Visso
111 months ago · 27 Apr, 23:16
Activity in the area right now (30 km radius)
10
last 24 hours
60
last 7 days
330
last 30 days
0 before2000 after
this quake
Strongest of the sequence4.0

How often does it happen here?

about every ~3 days

Within 50 km of this epicentre, a magnitude ≥ 3 earthquake has occurred on average this often: 1254 events in the last 11 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.

17036.9
Valnerina earthquake
14 January 1703 · 26 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
20166.6
Valnerina earthquake
30 October 2016 · 12 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
13286.5
Valnerina earthquake
1 December 1328 · 11 km from here
XCompletely destructive: most buildings are destroyed.
18326.4
Valle Umbra earthquake
13 January 1832 · 40 km from here
XCompletely destructive: most buildings are destroyed.

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

The closest seismic structure

Muccia-Castelluccio di Norcia

The epicentre sits above this source area: the deep structure where this area's earthquakes can originate.

estimated maximum magnitude 6.9between 2 and 10 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

2.0
4 km West of Valfornace
14 km North · 8 km
111 months ago
25 Apr, 12:32
1.2
3 km South-West of Preci
12 km South-West · 10 km
111 months ago
25 Apr, 13:45
0.9
4 km East of Muccia
17 km North · 9 km
111 months ago
25 Apr, 13:47
1.0
5 km North-West of Acquasanta Terme
28 km South-East · 20 km
111 months ago
25 Apr, 13:51
0.9
7 km West of Norcia
16 km South · 10 km
111 months ago
25 Apr, 13:57
1.1
2 km South-West of Ussita
5 km East · 6 km
111 months ago
25 Apr, 14:40
1.1
3 km South-West of Visso
4 km West · 12 km
111 months ago
25 Apr, 14:52
0.9
6 km North-East of Norcia
17 km South-East · 12 km
111 months ago
25 Apr, 15:00
0.9
4 km North-West of Ussita
4 km North-East · 5 km
111 months ago
25 Apr, 15:13
0.9
2 km South-East of Visso
0 km South · 10 km
111 months ago
25 Apr, 15:19

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).

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