All earthquakes
0.9
very light
EARTHQUAKE DETAILS

6 km South-West of Gubbio

130 months ago · 20 Oct, 23:41

A very light earthquake, probably not felt by people. At only a few km deep the shaking is felt more sharply at the surface.

Stronger than 22% of Italian events in the past year

Where

6 km South-West of GubbioEarthquakes 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.

0.3kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×1,413 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.

  • Perugia
    22 km from the epicentre
    first tremor in ~4 s
    main shaking in ~7 s
  • Foligno
    41 km from the epicentre
    first tremor in ~7 s
    main shaking in ~12 s
  • Arezzo
    51 km from the epicentre
    first tremor in ~9 s
    main shaking in ~15 s
  • Pesaro
    70 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

10 km
shallow
1.1 times the height of Mount Everest

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?

Aftershock

It is an aftershock: it follows a stronger quake (M2.8, 130 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

2.8
The mainshock
5 km South-East of Gubbio
130 months ago · 28 Sept, 18:08
Activity in the area right now (30 km radius)
1
last 24 hours
29
last 7 days
152
last 30 days
120 before172 after
this quake
Strongest of the sequence2.8

How often does it happen here?

about every ~5 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 898 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.

17816.5
Cagliese earthquake
3 June 1781 · 35 km from here
XCompletely destructive: most buildings are destroyed.
18326.4
Valle Umbra earthquake
13 January 1832 · 35 km from here
XCompletely destructive: most buildings are destroyed.
17516.4
Appennino umbro-marchigiano earthquake
27 July 1751 · 20 km from here
XCompletely destructive: most buildings are destroyed.
13526.3
Alta Valtiberina earthquake
25 December 1352 · 37 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

Gubbio Basin

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

estimated maximum magnitude 7.0between 2 and 7 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

0.7
5 km West of Pietralunga
21 km North-West · 8 km
130 months ago
21 Oct, 01:39
0.9
5 km West of Nocera Umbra
25 km South-East · 10 km
130 months ago
21 Oct, 04:49
0.9
4 km North of Gubbio
9 km North · 6 km
130 months ago
20 Oct, 16:28
0.8
5 km West of Pietralunga
24 km North-West · 8 km
130 months ago
20 Oct, 14:49
0.8
2 km South-West of Gubbio
4 km North-East · 7 km
130 months ago
21 Oct, 08:33
0.5
2 km East of Pietralunga
19 km North-West · 3 km
130 months ago
21 Oct, 09:52
1.0
6 km West of Pietralunga
21 km North-West · 6 km
130 months ago
21 Oct, 10:35
0.9
5 km North-West of Montone
21 km North-West · 9 km
130 months ago
20 Oct, 08:41
1.1
10 km East of Pietralunga
22 km North · 9 km
130 months ago
21 Oct, 16:42
1.6
1 km South-West of Gubbio
5 km North-East · 8 km
130 months ago
21 Oct, 16:49

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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