All earthquakes
1.8
very light
EARTHQUAKE DETAILS

2 km South of Gubbio

83 months ago · 16 Aug, 03:51

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 82% of Italian events in the past year

Where

2 km South 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.

7.6kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×63 its energy
M1this quakeM3

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 ≈ 19 s

Animation sped up ~4× compared to reality.

  • Perugia
    26 km from the epicentre
    first tremor in ~5 s
    main shaking in ~8 s
  • Foligno
    42 km from the epicentre
    first tremor in ~7 s
    main shaking in ~12 s
  • Arezzo
    53 km from the epicentre
    first tremor in ~9 s
    main shaking in ~15 s
  • Pesaro
    66 km from the epicentre
    first tremor in ~11 s
    main shaking in ~19 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 (~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: 83 months ago the same area had a stronger quake (M2.3). This can only be said after the fact — it was not predictable beforehand.

2.3
The mainshock
4 km West of Fiuminata
83 months ago · 23 Aug, 13:04
Activity in the area right now (30 km radius)
2
last 24 hours
33
last 7 days
162
last 30 days
65 before71 after
this quake
Strongest of the sequence2.3

How often does it happen here?

about every ~4 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 1000 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 · 32 km from here
XCompletely destructive: most buildings are destroyed.
18326.4
Valle Umbra earthquake
13 January 1832 · 37 km from here
XCompletely destructive: most buildings are destroyed.
17516.4
Appennino umbro-marchigiano earthquake
27 July 1751 · 19 km from here
XCompletely destructive: most buildings are destroyed.
13526.3
Alta Valtiberina earthquake
25 December 1352 · 38 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

0.3
8 km West of Costacciaro
11 km North-East · 13 km
83 months ago
16 Aug, 03:37
1.1
2 km South of Gubbio
0 km South · 8 km
83 months ago
16 Aug, 04:56
1.3
6 km East of Valfabbrica
21 km South-East · 63 km
83 months ago
16 Aug, 09:56
1.1
5 km South-East of Gualdo Tadino
24 km South-East · 10 km
83 months ago
15 Aug, 17:43
1.9
7 km North-East of Assisi
25 km South-East · 10 km
83 months ago
15 Aug, 17:10
1.1
6 km North-East of Assisi
25 km South-East · 10 km
83 months ago
15 Aug, 17:05
0.6
5 km South of Gubbio
3 km South-East · 10 km
83 months ago
15 Aug, 16:10
0.5
6 km North-West of Gubbio
8 km North-West · 7 km
83 months ago
17 Aug, 11:41
0.9
2 km South of Costacciaro
14 km East · 13 km
83 months ago
13 Aug, 10:47
0.1
8 km South-West of Cantiano
13 km North · 6 km
83 months ago
18 Aug, 22:29

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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