All earthquakes
0.2
very light
EARTHQUAKE DETAILS

3 km West of Ussita

54 months ago · 26 Dec, 23:38

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 0% of Italian events in the past year

Where

3 km 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.

0.1kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×15,849 its energy
M-1this quakeM1

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
  • Terni
    55 km from the epicentre
    first tremor in ~9 s
    main shaking in ~16 s
  • Teramo
    56 km from the epicentre
    first tremor in ~10 s
    main shaking in ~16 s
  • Perugia
    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 (~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?

Aftershock

It is an aftershock: it follows a stronger quake (M3.3, 55 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

3.3
The mainshock
2 km East of Sarnano
55 months ago · 14 Dec, 06:34
Activity in the area right now (30 km radius)
16
last 24 hours
68
last 7 days
339
last 30 days
365 before423 after
this quake
Strongest of the sequence3.3

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: 15468 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 · 26 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
20166.6
Valnerina earthquake
30 October 2016 · 12 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
13286.5
Valnerina earthquake
1 December 1328 · 12 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

1.6
3 km North-East of Norcia
16 km South · 9 km
54 months ago
27 Dec, 00:45
1.2
4 km West of Sant'Angelo in Pontano
26 km North-East · 23 km
54 months ago
26 Dec, 21:38
1.6
3 km South-West of Ussita
4 km South-East · 8 km
54 months ago
27 Dec, 01:58
1.5
4 km North-West of Gualdo
26 km North-East · 23 km
54 months ago
27 Dec, 03:25
1.5
4 km East of San Ginesio
25 km North-East · 23 km
54 months ago
26 Dec, 18:47
0.9
2 km East of Muccia
15 km North-West · 17 km
54 months ago
26 Dec, 18:45
0.7
54 months ago
26 Dec, 17:14
1.5
2 km East of Monte Cavallo
11 km West · 12 km
54 months ago
26 Dec, 17:10
1.2
6 km West of Arquata del Tronto
21 km South-East · 10 km
54 months ago
27 Dec, 06:38
0.9
5 km East of Cerreto di Spoleto
17 km South-West · 9 km
54 months ago
27 Dec, 07:12

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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