All earthquakes
1.6
very light
EARTHQUAKE DETAILS

M1.6 earthquake · 11 km North-East of Chieuti (FG)

8 years ago · 17 Apr 2018, 21:15

A very light earthquake, probably not felt by people. At only a few km deep the shaking is felt more sharply at the surface.

Stronger than 74% of Italian events in the past year

Where

11 km North-East of ChieutiEarthquakes in the province of FoggiaEarthquakes in Puglia

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

5 events
Magnitude:lightweakmoderatestrong

The energy released

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

3.8kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×126 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 ≈ 25 s

Animation sped up ~5× compared to reality.

  • San Severo
    42 km from the epicentre
    first tremor in ~7 s
    main shaking in ~12 s
  • Manfredonia
    60 km from the epicentre
    first tremor in ~10 s
    main shaking in ~17 s
  • Foggia
    60 km from the epicentre
    first tremor in ~10 s
    main shaking in ~17 s
  • Cerignola
    88 km from the epicentre
    first tremor in ~15 s
    main shaking in ~25 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

7 km
shallow

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

shallower than the area average (~15 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 (M2.1, 8 years ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

2.1
The mainshock
11 km North of San Nicandro Garganico
8 years ago · 11 Apr 2018, 01:21
Activity in the area right now (30 km radius)
0
last 24 hours
1
last 7 days
7
last 30 days
2 before2 after
this quake
Strongest of the sequence2.1

How often does it happen here?

about every ~9 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 492 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.

16276.7
Capitanata earthquake
30 July 1627 · 22 km from here
XCompletely destructive: most buildings are destroyed.
16276.0
Capitanata earthquake
7 August 1627 · 19 km from here
IXDestructive: many buildings partly or fully collapse.
16576.0
Capitanata earthquake
29 January 1657 · 25 km from here
IX-XCompletely destructive: most buildings are destroyed.
18755.9
Gargano earthquake
6 December 1875 · 43 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

Tocco Casauria-Tremiti

The epicentre lies about 22 km from Tocco Casauria-Tremiti, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 7.5between 11 and 20 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

2.0
3 km North-East of Lesina
12 km East · 19 km
8 years ago
20 Apr 2018, 11:35
2.1
8 years ago
11 Apr 2018, 01:21
2.0
8 years ago
28 Mar 2018, 01:23
1.6
2 km South-East of Lesina
13 km South-East · 7 km
8 years ago
14 May 2018, 04:44

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).