All earthquakes
1.7
very light
EARTHQUAKE DETAILS

M1.7 earthquake · 4 km North of Celano (AQ)

5 years ago · 22 Apr 2021, 12:02

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 78% of Italian events in the past year

Where

4 km North of CelanoEarthquakes 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

15 events
Magnitude:lightweakmoderatestrong

The energy released

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

5.4kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×89 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 ≈ 18 s

Animation sped up ~3× compared to reality.

  • L'Aquila
    24 km from the epicentre
    first tremor in ~4 s
    main shaking in ~8 s
  • Chieti
    52 km from the epicentre
    first tremor in ~9 s
    main shaking in ~15 s
  • Teramo
    60 km from the epicentre
    first tremor in ~10 s
    main shaking in ~17 s
  • Montesilvano
    61 km from the epicentre
    first tremor in ~10 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

9 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?

Aftershock

It is an aftershock: it follows a stronger quake (M2.4, 5 years ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

2.4
The mainshock
4 km North of Borgorose
5 years ago · 7 Apr 2021, 13:42
Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
10
last 30 days
7 before7 after
this quake
Strongest of the sequence2.4

How often does it happen here?

about every ~4 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 1066 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 · 13 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
17066.8
Maiella earthquake
3 November 1706 · 41 km from here
X-XICatastrophic: very few buildings remain standing; landslides and ground cracks.
17036.7
Aquilano earthquake
2 February 1703 · 42 km from here
XCompletely destructive: most buildings are destroyed.
14616.5
Aquilano earthquake
27 November 1461 · 21 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

Borbona-L'Aquila-Aremogna

The epicentre lies about 1 km from Borbona-L'Aquila-Aremogna, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 7.0between 2 and 14 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

1.1
5 km North-West of Borgorose
30 km West · 10 km
5 years ago
21 Apr 2021, 04:38
1.7
4 km North of Fossa
24 km North-West · 20 km
5 years ago
25 Apr 2021, 10:03
0.9
5 km South-West of Aielli
10 km South-West · 16 km
5 years ago
16 Apr 2021, 22:11
0.6
5 km East of Avezzano
13 km South-West · 13 km
5 years ago
15 Apr 2021, 05:12
0.9
2 km East of Popoli
24 km East · 12 km
5 years ago
30 Apr 2021, 08:55
1.4
4 km South-West of Avezzano
20 km South-West · 10 km
5 years ago
14 Apr 2021, 08:47
2.4
4 km North of Borgorose
29 km West · 9 km
5 years ago
7 Apr 2021, 13:42
1.1
5 years ago
3 Apr 2021, 06:55
1.3
3 km South-West of Navelli
15 km North-East · 10 km
5 years ago
14 May 2021, 02:10
2.0
5 years ago
14 May 2021, 10:11

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).