All earthquakes
2.9
light
EARTHQUAKE DETAILS

8 km North of Ancona

130 months ago · 1 Oct, 14:14

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

Stronger than 98% of Italian events in the past year

Where

8 km North of AnconaEarthquakes in the province of AnconaEarthquakes in Marche

How far away could it be felt?

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

  • up to ~8 km · felt only by some, at rest
    ≈ 100,000 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

4 events
Magnitude:lightweakmoderatestrong

The energy released

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

338kgof TNT equivalent
1.4 lightning bolts
M3
A magnitude 3 earthquake releases ×1.4 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 ≈ 25 s

Animation sped up ~5× compared to reality.

  • Ancona
    8 km from the epicentre
    first tremor in ~2 s
    main shaking in ~4 s
  • Fano
    43 km from the epicentre
    first tremor in ~7 s
    main shaking in ~13 s
  • Pesaro
    57 km from the epicentre
    first tremor in ~10 s
    main shaking in ~16 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

9 km
shallow
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 (~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 (M3.0, 131 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

3.0
The mainshock
17 km East of Sirolo
131 months ago · 21 Sept, 16:57
Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
2
last 30 days
2 before1 after
this quake
Strongest of the sequence3.0

How often does it happen here?

about every ~17 days

Within 50 km of this epicentre, a magnitude ≥ 2.5 earthquake has occurred on average this often: 241 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 · 46 km from here
IXDestructive: many buildings partly or fully collapse.
19305.8
Senigallia earthquake
30 October 1930 · 8 km from here
VIII-IXDestructive: many buildings partly or fully collapse.
16905.6
Costa anconetana earthquake
23 December 1690 · 15 km from here
VIII-IXDestructive: many buildings partly or fully collapse.
12695.6
Costa anconetana earthquake
September 1269 · 12 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 sits above this source area: the deep structure where this area's earthquakes can originate.

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

1.8
8 km North-East of Mondolfo
28 km North-West · 16 km
130 months ago
3 Oct, 15:30
3.0
17 km East of Sirolo
26 km East · 5 km
131 months ago
21 Sept, 16:57
1.6
18 km East of Sirolo
27 km East · 9 km
131 months ago
7 Sept, 11:38

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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