All earthquakes
1.4
very light
EARTHQUAKE DETAILS

6 km South of Castelsantangelo sul Nera

114 months ago · 11 Feb, 16:18

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 62% of Italian events in the past year

Where

6 km South of Castelsantangelo sul NeraEarthquakes 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.

1.9kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×251 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 ≈ 18 s

Animation sped up ~3× compared to reality.

  • Foligno
    33 km from the epicentre
    first tremor in ~6 s
    main shaking in ~10 s
  • Teramo
    49 km from the epicentre
    first tremor in ~8 s
    main shaking in ~14 s
  • Terni
    50 km from the epicentre
    first tremor in ~9 s
    main shaking in ~15 s
  • L'Aquila
    63 km from the epicentre
    first tremor in ~11 s
    main shaking in ~18 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: 113 months ago the same area had a stronger quake (M3.2). This can only be said after the fact — it was not predictable beforehand.

3.2
The mainshock
2 km South-West of Ussita
113 months ago · 26 Feb, 18:04
Activity in the area right now (30 km radius)
10
last 24 hours
52
last 7 days
320
last 30 days
0 before2000 after
this quake
Strongest of the sequence3.2

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: 16018 events in the last 11 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 · 16 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
17036.7
Aquilano earthquake
2 February 1703 · 46 km from here
XCompletely destructive: most buildings are destroyed.
20166.6
Valnerina earthquake
30 October 2016 · 4 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.

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

1.2
3 km West of Ussita
12 km North · 10 km
113 months ago
26 Feb, 14:52
0.5
4 km South of Norcia
11 km South · 8 km
113 months ago
26 Feb, 15:02
0.9
8 km North-West of Accumoli
9 km South · 13 km
113 months ago
26 Feb, 15:04
1.1
2 km North-East of Pieve Torina
22 km North-West · 8 km
113 months ago
26 Feb, 15:15
1.4
2 km North-West of Ussita
13 km North · 9 km
113 months ago
26 Feb, 15:18
0.8
6 km West of Norcia
9 km South-West · 10 km
113 months ago
26 Feb, 15:27
1.0
1 km South-West of Ussita
10 km North · 7 km
113 months ago
26 Feb, 15:33
0.9
113 months ago
26 Feb, 15:37
1.4
2 km West of Accumoli
17 km South-East · 11 km
113 months ago
26 Feb, 15:58
1.3
5 km North-East of Norcia
5 km South-East · 9 km
113 months ago
26 Feb, 16:01

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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