All earthquakes
2.1
light
EARTHQUAKE DETAILS

M2.1 earthquake · 3 km North-East of Taurano (AV)

9 years ago · 1 Feb 2017, 19:52

A light earthquake, rarely felt by people. At only a few km deep the shaking is felt more sharply at the surface.

Stronger than 90% of Italian events in the past year

Where

3 km North-East of TauranoEarthquakes in the province of AvellinoEarthquakes in Campania

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

12 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 ≈ 7 s

Animation sped up ~1× compared to reality.

  • Avellino
    11 km from the epicentre
    first tremor in ~2 s
    main shaking in ~3 s
  • Scafati
    21 km from the epicentre
    first tremor in ~4 s
    main shaking in ~6 s
  • Cava de' Tirreni
    23 km from the epicentre
    first tremor in ~4 s
    main shaking in ~7 s
  • Acerra
    25 km from the epicentre
    first tremor in ~4 s
    main shaking in ~7 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

6 km
shallow

At only a few km deep the shaking is felt more sharply at the surface.

in line with the area average (~5 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: 9 years ago the same area had a stronger quake (M2.2). This can only be said after the fact — it was not predictable beforehand.

2.2
The mainshock
3 km North-West of Trecase
9 years ago · 4 Feb 2017, 18:14
Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
10
last 30 days
1 before10 after
this quake
Strongest of the sequence2.2

How often does it happen here?

about every ~5 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 791 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.

14567.2
Appennino centro-meridionale earthquake
5 December 1456 · 43 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
16887.1
Sannio earthquake
5 June 1688 · 42 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
17326.8
Irpinia earthquake
29 November 1732 · 37 km from here
X-XICatastrophic: very few buildings remain standing; landslides and ground cracks.
17026.6
Sannio-Irpinia earthquake
14 March 1702 · 35 km from here
XCompletely destructive: most buildings are destroyed.

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

The closest seismic structure

Mirabella Eclano-Monteverde

The epicentre lies about 27 km from Mirabella Eclano-Monteverde, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 6.9between 1 and 16 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

1.1
4 km North-West of Terzigno
22 km West · 0 km
9 years ago
3 Feb 2017, 03:08
2.2
3 km North-West of Trecase
24 km South-West · 1 km
9 years ago
4 Feb 2017, 18:14
2.0
9 years ago
29 Jan 2017, 20:35
1.0
9 years ago
2 Mar 2017, 21:35
1.1
9 years ago
2 Mar 2017, 21:47
1.2
9 years ago
2 Mar 2017, 21:58
1.5
9 years ago
2 Mar 2017, 22:02
1.3
9 years ago
2 Mar 2017, 22:10
1.6
9 years ago
2 Mar 2017, 22:11
1.3
9 years ago
2 Mar 2017, 22:13

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).