All earthquakes
0.7
very light
EARTHQUAKE DETAILS

7 km North-West of Gubbio

35 months ago · 1 Aug, 18:53

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 11% of Italian events in the past year

Where

7 km North-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.

0.2kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×2,818 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 ≈ 17 s

Animation sped up ~3× compared to reality.

  • Perugia
    32 km from the epicentre
    first tremor in ~5 s
    main shaking in ~9 s
  • Arezzo
    48 km from the epicentre
    first tremor in ~8 s
    main shaking in ~14 s
  • Foligno
    51 km from the epicentre
    first tremor in ~9 s
    main shaking in ~15 s
  • Pesaro
    59 km from the epicentre
    first tremor in ~10 s
    main shaking in ~17 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

5 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: 34 months ago the same area had a stronger quake (M2.2). This can only be said after the fact — it was not predictable beforehand.

2.2
The mainshock
7 km North-West of Gubbio
34 months ago · 26 Aug, 22:15
Activity in the area right now (30 km radius)
7
last 24 hours
35
last 7 days
173
last 30 days
156 before145 after
this quake
Strongest of the sequence2.2

How often does it happen here?

about every ~7 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 597 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 · 24 km from here
XCompletely destructive: most buildings are destroyed.
18326.4
Valle Umbra earthquake
13 January 1832 · 46 km from here
XCompletely destructive: most buildings are destroyed.
17516.4
Appennino umbro-marchigiano earthquake
27 July 1751 · 26 km from here
XCompletely destructive: most buildings are destroyed.
13526.3
Alta Valtiberina earthquake
25 December 1352 · 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

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

0.5
8 km West of Cantiano
10 km North-East · 10 km
35 months ago
2 Aug, 03:04
1.1
5 km West of Fossato di Vico
20 km South-East · 11 km
35 months ago
2 Aug, 03:39
1.1
4 km West of Fossato di Vico
20 km South-East · 11 km
35 months ago
2 Aug, 03:40
1.0
4 km South-West of Cagli
19 km North-East · 11 km
35 months ago
1 Aug, 09:03
0.7
3 km East of Piobbico
23 km North · 1 km
35 months ago
1 Aug, 08:01
1.2
3 km North of Frontone
24 km North-East · 15 km
35 months ago
2 Aug, 07:26
1.0
4 km South of Gubbio
11 km South-East · 10 km
35 months ago
1 Aug, 05:57
1.5
11 km South of Montone
15 km South-West · 8 km
35 months ago
2 Aug, 09:16
1.0
2 km South-West of Sigillo
20 km East · 9 km
35 months ago
1 Aug, 04:02
1.2
3 km West of Fossato di Vico
20 km East · 10 km
35 months ago
2 Aug, 12:09

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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