All earthquakes
1.9
very light
EARTHQUAKE DETAILS

M1.9 earthquake · 7 km South-East of Faenza (RA)

11 years ago · 12 May 2015, 20:49

A very light earthquake, probably not felt by people. At this depth the shaking is felt, but rarely causes damage.

Stronger than 85% of Italian events in the past year

Where

7 km South-East of FaenzaEarthquakes in the province of RavennaEarthquakes in Emilia-Romagna

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

61 events
Magnitude:lightweakmoderatestrong

The energy released

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

11kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×45 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 ≈ 9 s

Animation sped up ~2× compared to reality.

  • Faenza
    7 km from the epicentre
    first tremor in ~3 s
    main shaking in ~5 s
  • Forlì
    9 km from the epicentre
    first tremor in ~3 s
    main shaking in ~6 s
  • Ravenna
    24 km from the epicentre
    first tremor in ~5 s
    main shaking in ~9 s
  • Imola
    25 km from the epicentre
    first tremor in ~5 s
    main shaking in ~9 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

18 km
medium depth
2 times the height of Mount Everest

At this depth the shaking is felt, but rarely causes damage.

in line with the area average (~13 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 (M4.0, 11 years ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

4.0
The mainshock
5 km South of Faenza
11 years ago · 24 Apr 2015, 17:02
Activity in the area right now (30 km radius)
0
last 24 hours
2
last 7 days
3
last 30 days
105 before15 after
this quake
Strongest of the sequence4.0

How often does it happen here?

about every ~7 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 651 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.

19196.4
Mugello earthquake
29 June 1919 · 49 km from here
XCompletely destructive: most buildings are destroyed.
17816.1
Faentino earthquake
4 April 1781 · 12 km from here
IX-XCompletely destructive: most buildings are destroyed.
16616.0
Appennino forlivese earthquake
22 March 1661 · 25 km from here
XCompletely destructive: most buildings are destroyed.
17686.0
Appennino forlivese earthquake
19 October 1768 · 34 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

Castel San Pietro Terme-Meldola

The epicentre sits above this source area: the deep structure where this area's earthquakes can originate.

estimated maximum magnitude 6.5between 2 and 8 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
4 km West of Forlì
7 km South-East · 8 km
11 years ago
12 May 2015, 21:00
2.1
7 km South-East of Faenza
1 km West · 10 km
11 years ago
12 May 2015, 20:08
1.7
7 km South-East of Faenza
1 km South-West · 9 km
11 years ago
12 May 2015, 21:53
1.2
4 km South-East of Faenza
3 km North-West · 22 km
11 years ago
12 May 2015, 22:22
1.2
4 km South of Faenza
4 km West · 24 km
11 years ago
12 May 2015, 19:00
1.8
6 km South-East of Faenza
1 km West · 11 km
11 years ago
12 May 2015, 18:40
1.5
6 km South of Faenza
4 km West · 23 km
11 years ago
12 May 2015, 18:37
1.8
6 km South-East of Faenza
1 km North-West · 10 km
11 years ago
12 May 2015, 18:03
1.6
5 km South-East of Faenza
2 km North-West · 21 km
11 years ago
12 May 2015, 17:56
1.7
5 km South-East of Faenza
2 km North-West · 21 km
11 years ago
12 May 2015, 17:55

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).