All earthquakes
2.6
light
EARTHQUAKE DETAILS

M2.6 earthquake · 6 km West of Medicina (BO)

5 years ago · 17 Feb 2021, 02:29

A light earthquake, rarely felt by people. Being deep, it is felt less at the surface.

Stronger than 96% of Italian events in the past year

Where

6 km West of MedicinaEarthquakes in the province of BolognaEarthquakes 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

4 events
Magnitude:lightweakmoderatestrong

The energy released

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

120kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×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 ≈ 15 s

Animation sped up ~3× compared to reality.

  • Imola
    14 km from the epicentre
    first tremor in ~6 s
    main shaking in ~11 s
  • Bologna
    22 km from the epicentre
    first tremor in ~7 s
    main shaking in ~12 s
  • Faenza
    32 km from the epicentre
    first tremor in ~8 s
    main shaking in ~14 s
  • Ferrara
    36 km from the epicentre
    first tremor in ~9 s
    main shaking in ~15 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

36 km
deep
4 times the height of Mount Everest

Being deep, it is felt less at the surface.

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?

Isolated quake

In the 30 days around this event no other quakes were recorded within 30 km: a one-off episode, very common in Italy.

Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
0
last 30 days
1 before2 after
this quake
Strongest of the sequence2.5

How often does it happen here?

about every ~35 days

Within 50 km of this epicentre, a magnitude ≥ 2.5 earthquake has occurred on average this often: 123 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 · 31 km from here
IX-XCompletely destructive: most buildings are destroyed.
16885.8
Romagna earthquake
11 April 1688 · 30 km from here
IXDestructive: many buildings partly or fully collapse.
17255.7
Appennino tosco-emiliano earthquake
29 October 1725 · 32 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
15055.6
Bolognese earthquake
3 January 1505 · 29 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

Castelvetro di Modena-Castel San Pietro Terme

The epicentre lies about 9 km from Castelvetro di Modena-Castel San Pietro Terme, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 6.8between 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

1.4
5 km North-East of Monzuno
29 km South-West · 26 km
5 years ago
27 Feb 2021, 04:45
2.5
5 km North-West of Baricella
24 km North · 33 km
5 years ago
5 Feb 2021, 10:17
2.1
3 km East of Pianoro
21 km South-West · 28 km
5 years ago
15 Mar 2021, 05:58

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).