All earthquakes
1.9
very light
EARTHQUAKE DETAILS

M1.9 earthquake · 4 km South-West of Terelle (FR)

7 years ago · 22 Dec 2018, 12:53

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

4 km South-West of TerelleEarthquakes in the province of FrosinoneEarthquakes in Lazio

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

15 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 ≈ 22 s

Animation sped up ~4× compared to reality.

  • Caserta
    65 km from the epicentre
    first tremor in ~11 s
    main shaking in ~19 s
  • Aversa
    73 km from the epicentre
    first tremor in ~12 s
    main shaking in ~21 s
  • Giugliano in Campania
    74 km from the epicentre
    first tremor in ~13 s
    main shaking in ~21 s
  • Latina
    75 km from the epicentre
    first tremor in ~13 s
    main shaking in ~22 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

15 km
medium depth
1.7 times the height of Mount Everest

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

in line with the area average (~12 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 (M3.1, 7 years ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

3.1
The mainshock
4 km North of Sora
7 years ago · 4 Dec 2018, 08:30
Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
5
last 30 days
7 before7 after
this quake
Strongest of the sequence3.1

How often does it happen here?

about every ~12 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 349 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.

13496.8
Lazio-Molise earthquake
9 September 1349 · 17 km from here
X-XICatastrophic: very few buildings remain standing; landslides and ground cracks.
16546.3
Sorano earthquake
24 July 1654 · 13 km from here
XCompletely destructive: most buildings are destroyed.
19845.9
Monti della Meta earthquake
7 May 1984 · 30 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
11205.8
Valle del Garigliano earthquake
25 March 1120 · 22 km from here
VIII-IXDestructive: many buildings partly or fully collapse.

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

The closest seismic structure

Venafro

The epicentre lies about 21 km from Venafro, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 6.6between 1 and 13 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

0.9
2 km East of Pofi
25 km West · 10 km
7 years ago
23 Dec 2018, 15:16
1.4
3 km South-East of Pofi
25 km West · 11 km
7 years ago
23 Dec 2018, 15:17
1.2
1 km East of San Donato Val di Comino
20 km North-East · 10 km
7 years ago
23 Dec 2018, 22:31
1.3
4 km South of Opi
26 km North-East · 15 km
7 years ago
17 Dec 2018, 05:11
2.1
3 km South of Opi
26 km North-East · 15 km
7 years ago
17 Dec 2018, 04:19
0.6
1 km North of Alvito
21 km North · 5 km
7 years ago
13 Dec 2018, 07:03
1.2
2 km West of Terelle
3 km North-East · 19 km
7 years ago
1 Jan 2019, 18:29
1.2
3 km West of Alvito
19 km North · 8 km
7 years ago
4 Jan 2019, 07:40
0.6
2 km North of Alvito
22 km North · 9 km
7 years ago
9 Jan 2019, 01:17
0.5
5 km North-East of Picinisco
24 km North-East · 7 km
7 years ago
4 Dec 2018, 20:19

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).