All earthquakes
2.1
light
EARTHQUAKE DETAILS

4 km South-East of San Pietro in Cerro

76 months ago · 28 May, 03:46

A light earthquake, rarely felt by people. At this depth the shaking is felt, but rarely causes damage.

Stronger than 90% of Italian events in the past year

Where

4 km South-East of San Pietro in CerroEarthquakes in the province of PiacenzaEarthquakes 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

2 events
Magnitude:lightweakmoderatestrong

The energy released

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

21kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×22 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 ≈ 19 s

Animation sped up ~4× compared to reality.

  • Cremona
    14 km from the epicentre
    first tremor in ~5 s
    main shaking in ~8 s
  • Piacenza
    19 km from the epicentre
    first tremor in ~5 s
    main shaking in ~9 s
  • Parma
    38 km from the epicentre
    first tremor in ~8 s
    main shaking in ~13 s
  • Brescia
    61 km from the epicentre
    first tremor in ~11 s
    main shaking in ~19 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

25 km
medium depth
2.9 times the height of Mount Everest

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

in line with the area average (~21 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 (M2.3, 77 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

2.3
The mainshock
3 km South of Busseto
77 months ago · 2 May, 12:49
Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
0
last 30 days
1 before0 after
this quake
Strongest of the sequence2.3

How often does it happen here?

about every ~6 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 683 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.

18025.6
Valle dell'Oglio earthquake
12 May 1802 · 47 km from here
VIII-IXDestructive: many buildings partly or fully collapse.
14385.6
Parmense earthquake
11 June 1438 · 29 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
19715.5
Parmense earthquake
15 July 1971 · 37 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
18325.5
Reggiano earthquake
13 March 1832 · 50 km from here
VII-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

Portalbera-Cremona

The epicentre lies about 1 km from Portalbera-Cremona, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 6.7between 2 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

2.3
3 km South of Busseto
12 km South-East · 29 km
77 months ago
2 May, 12:49

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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