All earthquakes
1.2
very light
EARTHQUAKE DETAILS

4 km North-East of Fossombrone

82 months ago · 5 Sept, 23:17

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 47% of Italian events in the past year

Where

4 km North-East of FossombroneEarthquakes in the province of Pesaro e UrbinoEarthquakes in Marche

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

19 events
Magnitude:lightweakmoderatestrong

The energy released

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

1.0kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×501 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 ≈ 16 s

Animation sped up ~3× compared to reality.

  • Fano
    19 km from the epicentre
    first tremor in ~3 s
    main shaking in ~6 s
  • Pesaro
    20 km from the epicentre
    first tremor in ~4 s
    main shaking in ~6 s
  • Rimini
    46 km from the epicentre
    first tremor in ~8 s
    main shaking in ~13 s
  • Ancona
    54 km from the epicentre
    first tremor in ~9 s
    main shaking in ~16 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 (~10 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: 82 months ago the same area had a stronger quake (M2.3). This can only be said after the fact — it was not predictable beforehand.

2.3
The mainshock
5 km North-East of Mondolfo
82 months ago · 29 Sept, 16:08
Activity in the area right now (30 km radius)
1
last 24 hours
8
last 7 days
32
last 30 days
7 before11 after
this quake
Strongest of the sequence2.3

How often does it happen here?

about every ~5 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 847 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.

17816.5
Cagliese earthquake
3 June 1781 · 27 km from here
XCompletely destructive: most buildings are destroyed.
17416.2
Fabrianese earthquake
24 April 1741 · 32 km from here
IXDestructive: many buildings partly or fully collapse.
13896.0
Alta Valtiberina earthquake
18 October 1389 · 46 km from here
IXDestructive: many buildings partly or fully collapse.
19305.8
Senigallia earthquake
30 October 1930 · 45 km from here
VIII-IXDestructive: many buildings partly or fully collapse.

Source: Parametric Catalogue of Italian Earthquakes CPTI15 (INGV, CC BY 4.0).

The closest seismic structure

Urbino-Camerino

The epicentre lies about 9 km from Urbino-Camerino, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 6.9between 3 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

0.8
83 months ago
2 Sept, 09:49
1.0
83 months ago
2 Sept, 03:16
2.2
83 months ago
2 Sept, 03:07
0.5
2 km North-East of Piobbico
25 km West · 1 km
83 months ago
29 Aug, 08:49
0.7
2 km South-West of Frontone
24 km South-West · 14 km
82 months ago
15 Sept, 18:44
1.7
2 km West of Sassoferrato
28 km South · 44 km
82 months ago
17 Sept, 05:14
0.8
3 km West of Sassoferrato
28 km South · 13 km
82 months ago
17 Sept, 07:55
1.4
4 km South-East of Mondavio
13 km East · 36 km
83 months ago
25 Aug, 03:23
1.7
5 km East of Piobbico
24 km South-West · 14 km
83 months ago
23 Aug, 16:12
0.8
3 km South-West of Mergo
30 km South-East · 15 km
82 months ago
20 Sept, 06:25

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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