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2.7
light
EARTHQUAKE DETAILS

M2.7 earthquake · 5 km South of Modica (RG)

3 years ago · 1 Oct 2023, 11:37

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

Stronger than 97% of Italian events in the past year

Where

5 km South of ModicaEarthquakes in the province of RagusaEarthquakes in Sicilia

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

13 events
Magnitude:lightweakmoderatestrong

The energy released

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

169kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×2.8 its energy
M2this quakeM4

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 ≈ 14 s

Animation sped up ~3× compared to reality.

  • Modica
    5 km from the epicentre
    first tremor in ~5 s
    main shaking in ~8 s
  • Ragusa
    16 km from the epicentre
    first tremor in ~5 s
    main shaking in ~9 s
  • Vittoria
    32 km from the epicentre
    first tremor in ~7 s
    main shaking in ~12 s
  • Siracusa
    40 km from the epicentre
    first tremor in ~8 s
    main shaking in ~14 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

26 km
medium depth
3 times the height of Mount Everest

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

deeper than the area average (~19 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?

Mainshock

It is the strongest quake of its sequence: so far it has been followed by 7 aftershocks within 30 km. Aftershocks tend to fade in number and strength over time.

Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
16
last 30 days
5 before7 after
this quake
Strongest of the sequence2.0

How often does it happen here?

about every ~4 months

Within 50 km of this epicentre, a magnitude ≥ 2.5 earthquake has occurred on average this often: 38 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.

16937.3
Sicilia sud-orientale earthquake
11 January 1693 · 34 km from here
XICatastrophic: very few buildings remain standing; landslides and ground cracks.
15426.7
Sicilia sud-orientale earthquake
10 December 1542 · 40 km from here
XCompletely destructive: most buildings are destroyed.
11696.5
Sicilia sud-orientale earthquake
4 February 1169 · 40 km from here
XCompletely destructive: most buildings are destroyed.
16936.1
Sicilia sud-orientale earthquake
9 January 1693 · 35 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

Scicli-Giarratana

The epicentre lies about 7 km from Scicli-Giarratana, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 7.0between 1 and 23 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

1.8
3 km South-West of Ragusa
17 km West · 10 km
3 years ago
2 Oct 2023, 18:33
1.0
4 km South-West of Ragusa
18 km West · 7 km
3 years ago
2 Oct 2023, 20:26
1.6
11 km South of Pozzallo
25 km South · 10 km
3 years ago
8 Oct 2023, 06:08
1.0
6 km North-West of Modica
9 km North-West · 20 km
3 years ago
11 Oct 2023, 21:00
1.5
4 km North-West of Modica
8 km North-West · 21 km
3 years ago
11 Oct 2023, 21:00
1.5
6 km North-West of Modica
9 km North-West · 21 km
3 years ago
11 Oct 2023, 21:10
1.6
1 km West of Noto
17 km East · 21 km
3 years ago
18 Sept 2023, 20:07
2.0
10 km West of Pachino
23 km South-East · 10 km
3 years ago
18 Sept 2023, 03:10
1.5
8 km South-East of Ispica
26 km South-East · 11 km
3 years ago
18 Sept 2023, 03:09
1.4
4 km West of Scicli
21 km South-West · 29 km
3 years ago
15 Sept 2023, 20:10

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).