All earthquakes
0.8
very light
EARTHQUAKE DETAILS

M0.8 earthquake · 2 km North-East of Castiglione in Teverina (VT)

11 years ago · 8 May 2015, 11:59

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 17% of Italian events in the past year

Where

2 km North-East of Castiglione in TeverinaEarthquakes in the province of ViterboEarthquakes 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

11 events
Magnitude:lightweakmoderatestrong

The energy released

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

0.2kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×1,995 its energy
M0this quakeM2

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 ≈ 18 s

Animation sped up ~3× compared to reality.

  • Viterbo
    31 km from the epicentre
    first tremor in ~5 s
    main shaking in ~9 s
  • Terni
    39 km from the epicentre
    first tremor in ~7 s
    main shaking in ~11 s
  • Perugia
    53 km from the epicentre
    first tremor in ~9 s
    main shaking in ~15 s
  • Foligno
    62 km from the epicentre
    first tremor in ~10 s
    main shaking in ~18 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

5 km
shallow

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

in line with the area average (~9 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 (M1.5, 11 years ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

1.5
The mainshock
5 km South of Acquasparta
11 years ago · 2 May 2015, 19:13
Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
0
last 30 days
5 before5 after
this quake
Strongest of the sequence1.5

How often does it happen here?

about every ~10 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 439 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.

18326.4
Valle Umbra earthquake
13 January 1832 · 49 km from here
XCompletely destructive: most buildings are destroyed.
16955.8
Lazio settentrionale earthquake
11 June 1695 · 8 km from here
IXDestructive: many buildings partly or fully collapse.
12775.6
Spoleto earthquake
1277 · 46 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
12765.6
Orvietano earthquake
22 May 1276 · 10 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

Mugello-Citta' di Castello-Leonessa

The epicentre lies about 43 km from Mugello-Citta' di Castello-Leonessa, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 6.9between 1 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

0.9
11 years ago
9 May 2015, 22:32
1.2
5 km North of San Gemini
29 km East · 8 km
11 years ago
5 May 2015, 21:56
1.2
5 km West of Acquasparta
28 km East · 9 km
11 years ago
11 May 2015, 23:51
1.0
6 km South-West of Allerona
23 km North-West · 1 km
11 years ago
13 May 2015, 07:35
1.5
5 km South of Acquasparta
30 km East · 8 km
11 years ago
2 May 2015, 19:13
0.9
11 years ago
28 May 2015, 03:20
1.5
11 years ago
28 May 2015, 11:55
1.4
3 km West of Massa Martana
29 km East · 8 km
11 years ago
15 Apr 2015, 12:45
1.4
11 years ago
14 Apr 2015, 05:38
1.0
11 years ago
10 Apr 2015, 20:59

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).