All earthquakes
1.2
very light
EARTHQUAKE DETAILS

3 km South-West of Ussita

52 months ago · 20 Mar, 10:20

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 47% of Italian events in the past year

Where

3 km South-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.

1.0kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×501 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 ≈ 20 s

Animation sped up ~4× compared to reality.

  • Foligno
    29 km from the epicentre
    first tremor in ~5 s
    main shaking in ~9 s
  • Teramo
    53 km from the epicentre
    first tremor in ~9 s
    main shaking in ~15 s
  • Terni
    55 km from the epicentre
    first tremor in ~9 s
    main shaking in ~16 s
  • Perugia
    69 km from the epicentre
    first tremor in ~12 s
    main shaking in ~20 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

6 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 (M3.4, 52 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

3.4
The mainshock
5 km South-East of Accumoli
52 months ago · 27 Feb, 14:07
Activity in the area right now (30 km radius)
14
last 24 hours
68
last 7 days
338
last 30 days
390 before441 after
this quake
Strongest of the sequence3.4

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: 15703 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 · 24 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
20166.6
Valnerina earthquake
30 October 2016 · 10 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
13286.5
Valnerina earthquake
1 December 1328 · 13 km from here
XCompletely destructive: most buildings are destroyed.
18326.4
Valle Umbra earthquake
13 January 1832 · 45 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
5 km North-East of Cittareale
29 km South · 11 km
52 months ago
20 Mar, 09:12
0.6
52 months ago
20 Mar, 08:49
1.4
2 km West of Monte Cavallo
17 km North-West · 12 km
52 months ago
20 Mar, 13:14
0.9
5 km South-East of Sellano
17 km West · 11 km
52 months ago
20 Mar, 13:23
1.3
5 km North-East of Preci
7 km West · 10 km
52 months ago
20 Mar, 14:30
1.3
3 km North-West of Accumoli
22 km South-East · 11 km
52 months ago
20 Mar, 18:04
1.0
3 km East of Sellano
18 km West · 11 km
52 months ago
20 Mar, 02:10
0.6
3 km East of Sellano
18 km West · 11 km
52 months ago
20 Mar, 01:45
0.9
2 km West of Visso
8 km West · 10 km
52 months ago
20 Mar, 01:34
1.0
4 km West of Ussita
3 km North-West · 13 km
52 months ago
20 Mar, 19:56

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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