All earthquakes
1.8
very light
EARTHQUAKE DETAILS

1 km South-East of Mercatino Conca

69 months ago · 21 Oct, 18:02

A very light earthquake, probably not felt by people. Being deep, it is felt less at the surface.

Stronger than 82% of Italian events in the past year

Where

1 km South-East of Mercatino ConcaEarthquakes 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

8 events
Magnitude:lightweakmoderatestrong

The energy released

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

7.6kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×63 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 ≈ 16 s

Animation sped up ~3× compared to reality.

  • Rimini
    19 km from the epicentre
    first tremor in ~8 s
    main shaking in ~14 s
  • Pesaro
    25 km from the epicentre
    first tremor in ~8 s
    main shaking in ~15 s
  • Cesena
    36 km from the epicentre
    first tremor in ~10 s
    main shaking in ~16 s
  • Fano
    37 km from the epicentre
    first tremor in ~10 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

44 km
deep
5 times the height of Mount Everest

Being deep, it is felt less at the surface.

deeper than 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: 69 months ago the same area had a stronger quake (M2.0). This can only be said after the fact — it was not predictable beforehand.

2.0
The mainshock
2 km South-West of Mercatino Conca
69 months ago · 21 Oct, 18:35
Activity in the area right now (30 km radius)
1
last 24 hours
3
last 7 days
17
last 30 days
2 before5 after
this quake
Strongest of the sequence2.0

How often does it happen here?

about every ~8 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 506 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 · 29 km from here
XCompletely destructive: most buildings are destroyed.
13896.0
Alta Valtiberina earthquake
18 October 1389 · 41 km from here
IXDestructive: many buildings partly or fully collapse.
15846.0
Appennino forlivese earthquake
10 September 1584 · 43 km from here
IXDestructive: many buildings partly or fully collapse.
19186.0
Appennino forlivese earthquake
10 November 1918 · 48 km from here
IXDestructive: many buildings partly or fully collapse.

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

The closest seismic structure

Riminese onshore

The epicentre lies about 6 km from Riminese onshore, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 7.0between 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

2.0
69 months ago
21 Oct, 18:35
0.7
3 km North-West of Piobbico
29 km South · 11 km
69 months ago
22 Oct, 05:06
1.2
4 km North-East of Piobbico
28 km South · 11 km
69 months ago
5 Oct, 19:49
0.7
2 km North of Piobbico
30 km South · 10 km
68 months ago
9 Nov, 00:56
0.3
4 km North-East of Piobbico
28 km South · 1 km
68 months ago
9 Nov, 10:11
0.8
5 km West of Urbino
13 km South-East · 9 km
69 months ago
2 Oct, 18:51
0.6
4 km South of Urbania
27 km South · 11 km
68 months ago
11 Nov, 05:44

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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