All earthquakes
3.3
weak
EARTHQUAKE DETAILS

2 km North-East of Ussita

94 months ago · 11 Sept, 23:57

A weak earthquake, felt by some of the population. At only a few km deep the shaking is felt more sharply at the surface.

Stronger than 99% of Italian events in the past yearNo. 4 of the year in Marche

Where

2 km North-East of UssitaEarthquakes in the province of MacerataEarthquakes in Marche

How far away could it be felt?

An estimate of how far people may have felt this quake.

  • up to ~18 km · felt only by some, at rest
    ≈ 16,000 people live in this area

The coloured rings on the map below show these distances.

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.

1.3tof TNT equivalent
5.6 lightning bolts
M3
×2.8 the energy of a magnitude 3 earthquake
M2this quakeM4

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
    31 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
    59 km from the epicentre
    first tremor in ~10 s
    main shaking in ~17 s
  • Perugia
    70 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

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?

Mainshock

It is the strongest quake of its sequence: so far it has been followed by 580 aftershocks within 30 km. Aftershocks tend to fade in number and strength over time.

Activity in the area right now (30 km radius)
8
last 24 hours
59
last 7 days
324
last 30 days
591 before580 after
this quake
Strongest of the sequence2.8

How often does it happen here?

about every ~3 days

Within 50 km of this epicentre, a magnitude ≥ 3 earthquake has occurred on average this often: 1253 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 · 17 km from here
XCompletely destructive: most buildings are destroyed.
18326.4
Valle Umbra earthquake
13 January 1832 · 47 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 lies about 1 km from Muccia-Castelluccio di Norcia, one of the seismic structures mapped by INGV geologists.

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
2 km East of Muccia
17 km North-West · 9 km
94 months ago
11 Sept, 23:22
0.8
3 km East of Muccia
16 km North-West · 8 km
94 months ago
11 Sept, 22:35
1.3
3 km North-East of Preci
12 km South-West · 10 km
94 months ago
12 Sept, 01:20
0.9
3 km North-East of Ussita
1 km North · 7 km
94 months ago
12 Sept, 01:24
1.5
2 km South-West of Norcia
21 km South · 11 km
94 months ago
12 Sept, 01:25
2.3
3 km East of Muccia
16 km North-West · 8 km
94 months ago
11 Sept, 22:13
1.4
7 km North-East of Sellano
19 km West · 11 km
94 months ago
11 Sept, 21:08
1.1
5 km North of Preci
12 km West · 10 km
94 months ago
12 Sept, 02:46
1.5
3 km North-East of Preci
12 km South-West · 10 km
94 months ago
11 Sept, 20:47
1.8
2 km South-East of Muccia
17 km North-West · 8 km
94 months ago
11 Sept, 20:03

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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