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2.7
light
EARTHQUAKE DETAILS

5 km North of Arquata del Tronto

53 months ago · 18 Feb, 07:42

A light earthquake, rarely felt by people. At only a few km deep the shaking is felt more sharply at the surface.

Stronger than 97% of Italian events in the past year

Where

5 km North of Arquata del TrontoEarthquakes in the province of Ascoli PicenoEarthquakes in Marche

How far away could it be felt?

An estimate of how far people may have felt this quake.

  • up to ~2 km · felt only by some, at rest

The coloured rings on the map below show these distances.

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.

169kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×2.8 its energy
M2this quakeM4

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 ≈ 17 s

Animation sped up ~3× compared to reality.

  • Teramo
    38 km from the epicentre
    first tremor in ~6 s
    main shaking in ~11 s
  • Foligno
    44 km from the epicentre
    first tremor in ~7 s
    main shaking in ~13 s
  • Terni
    57 km from the epicentre
    first tremor in ~10 s
    main shaking in ~16 s
  • L'Aquila
    58 km from the epicentre
    first tremor in ~10 s
    main shaking in ~17 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

8 km
shallow

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: 52 months ago the same area had a stronger quake (M3.4). This can only be said after the fact — it was not predictable beforehand.

3.4
The mainshock
5 km South-East of Accumoli
52 months ago · 27 Feb, 14:07
Activity in the area right now (30 km radius)
15
last 24 hours
43
last 7 days
257
last 30 days
349 before323 after
this quake
Strongest of the sequence3.4

How often does it happen here?

about every ~1 days

Within 50 km of this epicentre, a magnitude ≥ 2.5 earthquake has occurred on average this often: 4497 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.

17036.9
Valnerina earthquake
14 January 1703 · 21 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
17036.7
Aquilano earthquake
2 February 1703 · 41 km from here
XCompletely destructive: most buildings are destroyed.
20166.6
Valnerina earthquake
30 October 2016 · 15 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
13286.5
Valnerina earthquake
1 December 1328 · 23 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

Accumoli-Amatrice

The epicentre lies about 3 km from Accumoli-Amatrice, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 6.5between 2 and 9 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
2 km South-West of Pieve Torina
30 km North-West · 8 km
53 months ago
18 Feb, 06:45
0.9
2 km South-West of Pieve Torina
30 km North-West · 7 km
53 months ago
18 Feb, 05:27
0.8
1 km West of Accumoli
12 km South-West · 11 km
53 months ago
18 Feb, 05:01
0.5
5 km East of Accumoli
14 km South · 14 km
53 months ago
18 Feb, 04:46
1.3
3 km South-East of Norcia
11 km West · 9 km
53 months ago
18 Feb, 11:09
0.8
5 km East of Accumoli
14 km South · 12 km
53 months ago
18 Feb, 02:38
0.7
7 km East of Sellano
28 km West · 11 km
53 months ago
18 Feb, 02:07
1.2
5 km North-East of Norcia
9 km West · 10 km
53 months ago
18 Feb, 18:04
2.6
4 km South-West of Visso
24 km North-West · 8 km
53 months ago
17 Feb, 21:20
2.2
4 km South-West of Visso
24 km North-West · 7 km
53 months ago
17 Feb, 19:53

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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