All earthquakes
0.7
very light
EARTHQUAKE DETAILS

M0.7 earthquake · 2 km East of Opi (AQ)

9 years ago · 31 Aug 2017, 22:18

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 11% of Italian events in the past year

Where

2 km East 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

29 events
Magnitude:lightweakmoderatestrong

The energy released

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

0.2kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×2,818 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.

  • Chieti
    68 km from the epicentre
    first tremor in ~11 s
    main shaking in ~20 s
  • L'Aquila
    69 km from the epicentre
    first tremor in ~12 s
    main shaking in ~20 s
  • Pescara
    82 km from the epicentre
    first tremor in ~14 s
    main shaking in ~23 s
  • Montesilvano
    82 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?

Aftershock

It is an aftershock: it follows a stronger quake (M2.1, 9 years ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

2.1
The mainshock
1 km East of Opi
9 years ago · 31 Aug 2017, 13:39
Activity in the area right now (30 km radius)
4
last 24 hours
6
last 7 days
19
last 30 days
11 before17 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: 394 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 · 38 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
17066.8
Maiella earthquake
3 November 1706 · 37 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 · 22 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

0.5
1 km South-East of Opi
2 km South-West · 11 km
9 years ago
31 Aug 2017, 19:17
0.8
1 km East of Opi
1 km West · 10 km
9 years ago
1 Sept 2017, 03:28
2.1
1 km East of Opi
1 km West · 10 km
9 years ago
31 Aug 2017, 13:39
1.7
2 km North-West of Gioia dei Marsi
20 km North-West · 22 km
9 years ago
28 Aug 2017, 15:08
1.5
2 km North-East of Cansano
28 km North-East · 20 km
9 years ago
27 Aug 2017, 00:23
1.3
3 km West of Opi
4 km West · 9 km
9 years ago
8 Sept 2017, 10:15
1.4
9 years ago
9 Sept 2017, 09:33
0.1
3 km North-West of Scanno
14 km North · 22 km
9 years ago
10 Sept 2017, 07:08
1.7
9 years ago
22 Aug 2017, 00:08
1.0
3 km North-West of Villetta Barrea
6 km North-East · 10 km
9 years ago
20 Aug 2017, 13:28

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).