All earthquakes
1.3
very light
EARTHQUAKE DETAILS

3 km West of Opi

122 months ago · 19 Aug, 01:26

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 55% of Italian events in the past year

Where

3 km 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

24 events
Magnitude:lightweakmoderatestrong

The energy released

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

1.3kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×355 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 ≈ 24 s

Animation sped up ~4× compared to reality.

  • L'Aquila
    67 km from the epicentre
    first tremor in ~11 s
    main shaking in ~19 s
  • Chieti
    69 km from the epicentre
    first tremor in ~12 s
    main shaking in ~20 s
  • Montesilvano
    83 km from the epicentre
    first tremor in ~14 s
    main shaking in ~24 s
  • Caserta
    83 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

9 km
shallow
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
4
last 7 days
14
last 30 days
15 before8 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: 385 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 · 36 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 · 27 km from here
X-XICatastrophic: very few buildings remain standing; landslides and ground cracks.
16546.3
Sorano earthquake
24 July 1654 · 19 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

1.5
4 km West of Opi
1 km West · 11 km
122 months ago
19 Aug, 09:11
1.5
2 km West of Opi
1 km South-East · 10 km
122 months ago
16 Aug, 10:43
0.8
122 months ago
16 Aug, 09:28
1.0
3 km West of Opi
0 km South · 9 km
122 months ago
21 Aug, 23:19
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
1.5
2 km South-West of Opi
1 km South-East · 10 km
122 months ago
23 Aug, 13:40
1.1
3 km West of Opi
0 km South · 10 km
122 months ago
14 Aug, 00:57
1.9
3 km West of Opi
1 km South-West · 11 km
122 months ago
14 Aug, 00:07
1.0
3 km West of Opi
1 km South-West · 11 km
122 months ago
13 Aug, 23:53

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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