All earthquakes
4.0
moderate
EARTHQUAKE DETAILS

6 km South-West of Montemonaco

119 months ago · 27 Aug, 04:50

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

No. 4 of the month in ItalyStronger than 99% of Italian events in the past yearNo. 2 of the year in MarcheThe strongest of the past 12 months within 50 km

Where

6 km South-West of MontemonacoEarthquakes 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 ~18 km · felt by many people, especially on upper floors
    ≈ 19,000 people live in this area
  • up to ~44 km · felt only by some, at rest
    ≈ 409,000 people live in this area

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.

15tof TNT equivalent
63 lightning bolts
M3
×32 the energy of a magnitude 3 earthquake
M3this quakeM5

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.

  • Foligno
    39 km from the epicentre
    first tremor in ~7 s
    main shaking in ~11 s
  • Teramo
    43 km from the epicentre
    first tremor in ~7 s
    main shaking in ~13 s
  • Terni
    56 km from the epicentre
    first tremor in ~9 s
    main shaking in ~16 s
  • L'Aquila
    62 km from the epicentre
    first tremor in ~11 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

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?

Isolated quake

In the 30 days around this event no other quakes were recorded within 30 km: a one-off episode, very common in Italy.

Activity in the area right now (30 km radius)
17
last 24 hours
58
last 7 days
303
last 30 days
0 before2000 after
this quake
Strongest of the sequence3.7

How often does it happen here?

about every ~56 days

Within 50 km of this epicentre, a magnitude ≥ 4 earthquake has occurred on average this often: 75 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 · 20 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
17036.7
Aquilano earthquake
2 February 1703 · 46 km from here
XCompletely destructive: most buildings are destroyed.
20166.6
Valnerina earthquake
30 October 2016 · 11 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
13286.5
Valnerina earthquake
1 December 1328 · 18 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

Muccia-Castelluccio di Norcia

The epicentre lies about 1 km from Muccia-Castelluccio di Norcia, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 6.9between 2 and 10 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

1.2
7 km West of Arquata del Tronto
7 km South-West · 10 km
119 months ago
18 Sept, 02:13
1.4
1 km North-West of Monte Cavallo
27 km North-West · 12 km
119 months ago
18 Sept, 02:16
1.0
119 months ago
18 Sept, 02:18
1.4
2 km North-West of Norcia
11 km South-West · 10 km
119 months ago
18 Sept, 02:32
1.1
119 months ago
18 Sept, 02:35
1.6
119 months ago
18 Sept, 02:42
1.1
5 km East of Accumoli
18 km South · 9 km
119 months ago
18 Sept, 02:48
1.3
6 km North-West of Campotosto
29 km South · 11 km
119 months ago
18 Sept, 02:54
1.0
3 km North of Norcia
9 km South-West · 10 km
119 months ago
18 Sept, 02:59
1.3
4 km North-East of Norcia
7 km South-West · 11 km
119 months ago
18 Sept, 03:06

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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