All earthquakes
1.0
very light
EARTHQUAKE DETAILS

3 km North-West of Ussita

57 months ago · 25 Sept, 01:51

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 30% of Italian events in the past year

Where

3 km North-West of UssitaEarthquakes in the province of MacerataEarthquakes in Marche

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.

0.5kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×1,000 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 ≈ 19 s

Animation sped up ~4× compared to reality.

  • Foligno
    27 km from the epicentre
    first tremor in ~5 s
    main shaking in ~8 s
  • Teramo
    57 km from the epicentre
    first tremor in ~10 s
    main shaking in ~17 s
  • Terni
    57 km from the epicentre
    first tremor in ~10 s
    main shaking in ~17 s
  • Perugia
    67 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

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 (~11 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: 57 months ago the same area had a stronger quake (M3.7). This can only be said after the fact — it was not predictable beforehand.

3.7
The mainshock
4 km South-East of Visso
57 months ago · 18 Oct, 14:54
Activity in the area right now (30 km radius)
8
last 24 hours
58
last 7 days
331
last 30 days
383 before431 after
this quake
Strongest of the sequence3.7

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: 15283 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 · 28 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
20166.6
Valnerina earthquake
30 October 2016 · 14 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
13286.5
Valnerina earthquake
1 December 1328 · 15 km from here
XCompletely destructive: most buildings are destroyed.
18326.4
Valle Umbra earthquake
13 January 1832 · 43 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

Muccia-Castelluccio di Norcia

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

estimated maximum magnitude 6.9between 2 and 10 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

1.0
1 km East of Monte Cavallo
12 km West · 15 km
57 months ago
24 Sept, 22:59
0.7
1 km North-West of Foligno
28 km West · 10 km
57 months ago
24 Sept, 22:23
0.9
7 km North-West of Arquata del Tronto
18 km South-East · 13 km
57 months ago
25 Sept, 06:52
1.5
5 km North-East of Preci
9 km South-West · 11 km
57 months ago
24 Sept, 20:35
0.7
2 km West of Pieve Torina
11 km West · 9 km
57 months ago
25 Sept, 07:31
1.1
8 km South-West of Montemonaco
16 km South-East · 14 km
57 months ago
24 Sept, 17:22
0.8
0 km North of Fiastra
11 km North · 9 km
57 months ago
24 Sept, 16:08
1.1
1 km South-East of Preci
13 km South-West · 11 km
57 months ago
24 Sept, 14:19
0.6
3 km West of Muccia
18 km North-West · 12 km
57 months ago
25 Sept, 13:29
1.0
57 months ago
25 Sept, 14:18

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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