All earthquakes
0.9
very light
EARTHQUAKE DETAILS

4 km North-East of Valtopina

35 months ago · 12 Aug, 11:32

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

Stronger than 22% of Italian events in the past year

Where

4 km North-East of ValtopinaEarthquakes 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 ≈ 23 s

Animation sped up ~4× compared to reality.

  • Foligno
    11 km from the epicentre
    first tremor in ~3 s
    main shaking in ~6 s
  • Perugia
    37 km from the epicentre
    first tremor in ~7 s
    main shaking in ~12 s
  • Terni
    56 km from the epicentre
    first tremor in ~10 s
    main shaking in ~17 s
  • Ancona
    78 km from the epicentre
    first tremor in ~13 s
    main shaking in ~23 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

18 km
medium depth
2 times the height of Mount Everest

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

deeper than 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 (M1.9, 35 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

1.9
The mainshock
5 km North of Muccia
35 months ago · 3 Aug, 08:16
Activity in the area right now (30 km radius)
5
last 24 hours
44
last 7 days
239
last 30 days
212 before235 after
this quake
Strongest of the sequence1.9

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: 11538 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.

17036.9
Valnerina earthquake
14 January 1703 · 47 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
20166.6
Valnerina earthquake
30 October 2016 · 38 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
13286.5
Valnerina earthquake
1 December 1328 · 31 km from here
XCompletely destructive: most buildings are destroyed.
18326.4
Valle Umbra earthquake
13 January 1832 · 19 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

0.9
6 km East of Castel Ritaldi
28 km South · 9 km
35 months ago
12 Aug, 11:48
1.2
2 km North-East of Foligno
10 km South · 11 km
35 months ago
12 Aug, 09:44
0.8
2 km West of Serravalle di Chienti
12 km South-East · 6 km
35 months ago
12 Aug, 09:27
1.3
4 km South of Nocera Umbra
2 km North · 11 km
35 months ago
12 Aug, 05:06
1.0
5 km North-East of Valtopina
0 km North · 13 km
35 months ago
12 Aug, 05:05
1.1
3 km South-West of Spello
16 km South-West · 9 km
35 months ago
12 Aug, 18:49
0.5
35 months ago
12 Aug, 00:15
0.5
35 months ago
12 Aug, 23:16
0.7
4 km East of Pieve Torina
24 km East · 8 km
35 months ago
13 Aug, 03:50
0.6
35 months ago
13 Aug, 13:05

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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