All earthquakes
1.9
very light
EARTHQUAKE DETAILS

5 km South-West of Russi

29 months ago · 1 Apr, 07:01

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

5 km South-West of RussiEarthquakes 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

14 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 ≈ 11 s

Animation sped up ~2× compared to reality.

  • Forlì
    12 km from the epicentre
    first tremor in ~5 s
    main shaking in ~8 s
  • Faenza
    12 km from the epicentre
    first tremor in ~5 s
    main shaking in ~8 s
  • Ravenna
    13 km from the epicentre
    first tremor in ~5 s
    main shaking in ~8 s
  • Imola
    27 km from the epicentre
    first tremor in ~6 s
    main shaking in ~11 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

26 km
medium depth
3 times the height of Mount Everest

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

deeper than the area average (~14 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: 29 months ago the same area had a stronger quake (M2.4). This can only be said after the fact — it was not predictable beforehand.

2.4
The mainshock
4 km North-East of Castrocaro Terme e Terra del Sole
29 months ago · 21 Apr, 14:03
Activity in the area right now (30 km radius)
0
last 24 hours
4
last 7 days
4
last 30 days
3 before10 after
this quake
Strongest of the sequence2.4

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: 552 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.

17816.1
Faentino earthquake
4 April 1781 · 21 km from here
IX-XCompletely destructive: most buildings are destroyed.
16616.0
Appennino forlivese earthquake
22 March 1661 · 36 km from here
XCompletely destructive: most buildings are destroyed.
17686.0
Appennino forlivese earthquake
19 October 1768 · 44 km from here
IXDestructive: many buildings partly or fully collapse.
19186.0
Appennino forlivese earthquake
10 November 1918 · 46 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

Ascensione-Armaia

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

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

1.2
7 km East of Brisighella
19 km South-West · 20 km
29 months ago
2 Apr, 11:49
1.8
9 km South of Faenza
17 km South-West · 28 km
30 months ago
26 Mar, 23:15
1.7
7 km East of Brisighella
20 km South-West · 33 km
30 months ago
26 Mar, 23:05
1.1
30 months ago
14 Mar, 01:02
2.4
29 months ago
21 Apr, 14:03
1.3
28 months ago
30 Apr, 23:49
1.5
28 months ago
30 Apr, 23:58
2.0
28 months ago
1 May, 00:15
1.2
28 months ago
1 May, 00:23
1.8
28 months ago
1 May, 00:23

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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