All earthquakes
1.1
very light
EARTHQUAKE DETAILS

2 km West of Gualdo Tadino

75 months ago · 20 Apr, 17:49

A very light earthquake, probably not felt by people. At this depth the shaking is felt, but rarely causes damage.

Stronger than 38% of Italian events in the past year

Where

2 km West of Gualdo TadinoEarthquakes in the province of PerugiaEarthquakes in Umbria

How far away could it be felt?

A quake this small is usually not felt by people: only seismographs record it.

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.

0.7kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×708 its energy
M0this quakeM2

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 ≈ 20 s

Animation sped up ~4× compared to reality.

  • Foligno
    27 km from the epicentre
    first tremor in ~5 s
    main shaking in ~8 s
  • Perugia
    33 km from the epicentre
    first tremor in ~6 s
    main shaking in ~10 s
  • Fano
    69 km from the epicentre
    first tremor in ~12 s
    main shaking in ~20 s
  • Arezzo
    71 km from the epicentre
    first tremor in ~12 s
    main shaking in ~20 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

11 km
medium depth
1.2 times the height of Mount Everest

At this depth the shaking is felt, but rarely causes damage.

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?

Foreshock

In hindsight it was a foreshock: 75 months ago the same area had a stronger quake (M2.8). This can only be said after the fact — it was not predictable beforehand.

2.8
The mainshock
5 km North of Cerreto d'Esi
75 months ago · 22 Apr, 07:46
Activity in the area right now (30 km radius)
7
last 24 hours
38
last 7 days
172
last 30 days
154 before164 after
this quake
Strongest of the sequence2.8

How often does it happen here?

about every ~1 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 5897 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.

17816.5
Cagliese earthquake
3 June 1781 · 46 km from here
XCompletely destructive: most buildings are destroyed.
13286.5
Valnerina earthquake
1 December 1328 · 47 km from here
XCompletely destructive: most buildings are destroyed.
18326.4
Valle Umbra earthquake
13 January 1832 · 29 km from here
XCompletely destructive: most buildings are destroyed.
17516.4
Appennino umbro-marchigiano earthquake
27 July 1751 · 1 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

Colfiorito-Cittareale

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

estimated maximum magnitude 7.1between 3 and 14 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

0.8
5 km North-West of Nocera Umbra
7 km South-East · 11 km
75 months ago
20 Apr, 16:32
0.4
5 km North of Muccia
25 km East · 12 km
75 months ago
21 Apr, 02:32
0.8
75 months ago
21 Apr, 02:46
0.8
0 km South of Fiuminata
15 km East · 23 km
75 months ago
21 Apr, 08:29
0.5
9 km East of Pietralunga
29 km North-West · 10 km
75 months ago
19 Apr, 17:49
0.5
2 km North-West of Muccia
27 km South-East · 13 km
75 months ago
19 Apr, 15:00
0.9
1 km West of Castelraimondo
26 km East · 13 km
75 months ago
21 Apr, 22:05
1.4
8 km South-East of Pietralunga
28 km North-West · 8 km
75 months ago
21 Apr, 23:43
0.6
9 km North-West of Gubbio
28 km North-West · 7 km
75 months ago
19 Apr, 08:11
0.7
4 km South-East of Fossato di Vico
6 km North-East · 11 km
75 months ago
19 Apr, 03:53

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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