All earthquakes
2.2
light
EARTHQUAKE DETAILS

11 km North of Ancona

95 months ago · 18 Aug, 00:58

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

Stronger than 92% of Italian events in the past year

Where

11 km North of AnconaEarthquakes in the province of AnconaEarthquakes 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

7 events
Magnitude:lightweakmoderatestrong

The energy released

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

30kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×16 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 ≈ 25 s

Animation sped up ~5× compared to reality.

  • Ancona
    11 km from the epicentre
    first tremor in ~2 s
    main shaking in ~4 s
  • Fano
    45 km from the epicentre
    first tremor in ~8 s
    main shaking in ~13 s
  • Pesaro
    58 km from the epicentre
    first tremor in ~10 s
    main shaking in ~17 s
  • Rimini
    88 km from the epicentre
    first tremor in ~15 s
    main shaking in ~25 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?

Aftershock

It is an aftershock: it follows a stronger quake (M2.5, 95 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

2.5
The mainshock
4 km North-West of Ancona
95 months ago · 17 Aug, 06:12
Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
2
last 30 days
3 before3 after
this quake
Strongest of the sequence2.5

How often does it happen here?

about every ~6 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 718 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.

17416.2
Fabrianese earthquake
24 April 1741 · 49 km from here
IXDestructive: many buildings partly or fully collapse.
19305.8
Senigallia earthquake
30 October 1930 · 10 km from here
VIII-IXDestructive: many buildings partly or fully collapse.
16905.6
Costa anconetana earthquake
23 December 1690 · 16 km from here
VIII-IXDestructive: many buildings partly or fully collapse.
12695.6
Costa anconetana earthquake
September 1269 · 13 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.

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

The closest seismic structure

Conero onshore

The epicentre lies about 1 km from Conero onshore, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 5.9between 3 and 7 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

2.1
13 km North-East of Ancona
3 km East · 10 km
95 months ago
17 Aug, 20:00
2.5
4 km North-West of Ancona
7 km South-West · 7 km
95 months ago
17 Aug, 06:12
2.0
16 km East of Numana
30 km South-East · 7 km
95 months ago
25 Aug, 06:35
2.0
1 km South-West of Offagna
18 km South-West · 33 km
96 months ago
4 Aug, 10:27
1.1
9 km North-East of Ancona
2 km South-East · 10 km
95 months ago
3 Sept, 01:14
2.1
14 km East of Mondolfo
21 km North-West · 9 km
94 months ago
14 Sept, 20:31

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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