All earthquakes
1.5
very light
EARTHQUAKE DETAILS

2 km South-West of Opi

122 months ago · 23 Aug, 13:40

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 68% of Italian events in the past year

Where

2 km South-West of OpiEarthquakes in the province of L'AquilaEarthquakes in Abruzzo

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

25 events
Magnitude:lightweakmoderatestrong

The energy released

How much energy this quake unleashed, translated into everyday comparisons.

2.7kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×178 its energy
M1this quakeM3

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 ≈ 24 s

Animation sped up ~4× compared to reality.

  • L'Aquila
    68 km from the epicentre
    first tremor in ~12 s
    main shaking in ~20 s
  • Chieti
    70 km from the epicentre
    first tremor in ~12 s
    main shaking in ~20 s
  • Caserta
    83 km from the epicentre
    first tremor in ~14 s
    main shaking in ~24 s
  • Montesilvano
    84 km from the epicentre
    first tremor in ~14 s
    main shaking in ~24 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 (~12 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: 122 months ago the same area had a stronger quake (M2.1). This can only be said after the fact — it was not predictable beforehand.

2.1
The mainshock
1 km North of Pettorano sul Gizio
122 months ago · 26 Aug, 07:38
Activity in the area right now (30 km radius)
3
last 24 hours
5
last 7 days
13
last 30 days
14 before10 after
this quake
Strongest of the sequence2.1

How often does it happen here?

about every ~11 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 384 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.

19157.1
Marsica earthquake
13 January 1915 · 37 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
17066.8
Maiella earthquake
3 November 1706 · 40 km from here
X-XICatastrophic: very few buildings remain standing; landslides and ground cracks.
13496.8
Lazio-Molise earthquake
9 September 1349 · 26 km from here
X-XICatastrophic: very few buildings remain standing; landslides and ground cracks.
16546.3
Sorano earthquake
24 July 1654 · 20 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

Salto Lake-Ovindoli-Barrea

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

estimated maximum magnitude 7.1between 1 and 15 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
3 km West of Opi
1 km West · 9 km
122 months ago
21 Aug, 23:19
2.1
1 km North of Pettorano sul Gizio
25 km North-East · 26 km
122 months ago
26 Aug, 07:38
1.5
4 km West of Opi
2 km West · 11 km
122 months ago
19 Aug, 09:11
1.3
3 km West of Opi
1 km North-West · 9 km
122 months ago
19 Aug, 01:26
1.5
2 km West of Opi
1 km West · 10 km
122 months ago
16 Aug, 10:43
0.8
122 months ago
16 Aug, 09:28
1.5
4 km North of Pescasseroli
9 km North-West · 10 km
122 months ago
31 Aug, 03:49
1.6
3 km West of Opi
1 km West · 10 km
122 months ago
15 Aug, 13:32
1.1
3 km East of Scanno
16 km North-East · 22 km
122 months ago
15 Aug, 07:32
1.1
3 km West of Opi
1 km West · 10 km
122 months ago
14 Aug, 00:57

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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