Istituto Nazionale di Geofisica e Vulcanologia

Earthquake with magnitude of ML 0.5 on date 20-09-2023 and time 10:02:20 (UTC) in region 4 km E Marradi (FI)

A magnitude ML 0.5 earthquake occured in region: 4 km E Marradi (FI), on

  • 20-09-2023 10:02:20 (UTC)
  • 20-09-2023 12:02:20 (UTC +02:00) Italian time

and geographic coordinates (lat, lon) 44.0800, 11.6600 at 5 km depth.

The earthquake was located by: Sala Sismica INGV-Roma.

Search earthquakes: Any within 30 km radius

The values of hypocentral coordinates and magnitude may be revised at a later time as more information becomes available.

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Municipalities within 20 km from the epicenter

Distances are determinated based on the geographic coordintes of the (Istat).
Municipality Region Dist Inh Cum Inh
Marradi FI 4 3139 3139
Tredozio FC 7 1212 4351
Palazzuolo sul Senio FI 10 1154 5505
Portico e San Benedetto FC 11 756 6261
Modigliana FC 14 4560 10821
Rocca San Casciano FC 15 1910 12731
Premilcuore FC 15 799 13530
Casola Valsenio RA 16 2617 16147
San Godenzo FI 17 1167 17314
Brisighella RA 18 7639 24953
Dovadola FC 19 1653 26606
Castel del Rio BO 19 1246 27852

Municipalities with at least 50000 inhabitants

An earthquake occurred to
29 Km SW of Faenza (58541 inhabitants)
31 Km S of Imola (69797 inhabitants)
34 Km W of Forlì (117913 inhabitants)
47 Km W of Cesena (96758 inhabitants)
47 Km NE of Firenze (382808 inhabitants)
50 Km E of Prato (191150 inhabitants)
52 Km NE of Scandicci (50609 inhabitants)
53 Km SE of Bologna (386663 inhabitants)
57 Km SW of Ravenna (159116 inhabitants)
62 Km E of Pistoia (90315 inhabitants)
71 Km N of Arezzo (99543 inhabitants)
72 Km W of Rimini (147750 inhabitants)
84 Km S of Ferrara (133155 inhabitants)
86 Km SE of Modena (184973 inhabitants)
89 Km NE of Siena (53903 inhabitants)
96 Km E of Lucca (89046 inhabitants)
99 Km SE of Carpi (70699 inhabitants)
Recent and historical seismicity
Seismic hazard
Shakemap
Felt maps
Locations history
Type Magnitude Date and Time (UTC) Latitude Longitude Depth (km) Published time (UTC) Author Location ID
Reviewed
Rev100 		ML 0.5 2023-09-20
10:02:20		 44.0803 11.6603 5 2023-09-20
10:23:32		 Sala Sismica INGV-Roma 121272401
Preferred location and magnitude until now.
Origin information

Origin

Field Value
Time (UTC) 2023-09-20 10:02:20 ± 0.16
Latitude 44.0803 ± 0.0045
Longitude 11.6603 ± 0.0063
Depth (km) 5 ± 1 (from location)
Evaluation mode of Origin manual
Evaluation status of Origin reviewed
Version 100 -> SURVEY-INGV
Event type earthquake
Origin ID 121272401

Uncertainty

Field Value
Preferred uncertainty description uncertainty ellipse
Semi-major axis of confidence ellipse (meter) 577
Semi-minor axis of confidence ellipse (meter) 160
Azimuth of major axis of confidence ellipse. Measured clockwise from South-North direction at epicenter (gradi) 310
Circular confidence region, given by single value of horizontal uncertainty (meter) 580.0
Confidence level of the uncertainty (%) 68

Quality

Field Value
Largest azimuthal gap in station distribution as seen from epicenter (degree) 96
Number of associated phases, regardless of their use for origin computation 16
Number of defining phases 16
RMS of the travel time residuals of the arrivals used for the origin computation (sec) 0.22
Epicentral distance of station closest to the epicenter (degree) 0.03417
Epicentral distance of station farthest from the epicenter (degree) 0.26530
Number of stations at which the event was observed 8
Number of stations from which data was used for origin computation 8
Magnitude information

ML:0.5

Field Value
Value 0.5
Uncertainty 0.1
Num. used stations 8
Type of magnitude ML
Reference to an origin 121272401
Agency INGV
Autore Sala Sismica INGV-Roma
Time of creation (UTC) 2023-09-20 10:23:32
Picking and Arrival
SCNL Time Uncertainty Polarity Evaluation_mode Phase Azimuth Distance(km) Takeoff_angle Residual Weight
IV.RUFI.EHZ. 2023-09-20T10:02:31.13 0.6 undecidable manual S 204 29.4483 100 0.01 48
IV.SEI.HHZ. 2023-09-20T10:02:29.47 0.6 undecidable manual S 263 24.2535 103 0.14 47
IV.RINC.EHZ. 2023-09-20T10:02:28.78 0.6 undecidable manual S 191 21.9669 104 0.22 47
IV.VISG.HHZ. 2023-09-20T10:02:28.71 0.6 undecidable manual S 304 21.6672 104 0.25 46
IV.VMGN.HHZ. 2023-09-20T10:02:27.38 0.6 undecidable manual S 216 17.2716 107 0.38 46
IT.MOG.HNZ. 2023-09-20T10:02:26.09 0.6 undecidable manual S 40 13.0758 112 0.45 45
IV.RUFI.EHZ. 2023-09-20T10:02:26.39 0.6 positive manual P 204 29.4483 100 -0.33 45
IV.RINC.EHZ. 2023-09-20T10:02:25.30 0.6 negative manual P 191 21.9669 104 0.05 48
IV.VISG.HHZ. 2023-09-20T10:02:24.99 0.6 negative manual P 304 21.6672 104 -0.2 47
IV.SEI.HHZ. 2023-09-20T10:02:24.91 0.6 undecidable manual P 263 24.2535 103 -0.78 39
IV.VMGN.HHZ. 2023-09-20T10:02:24.48 0.6 positive manual P 216 17.2716 107 0.13 48
IT.MRR.HGZ. 2023-09-20T10:02:23.24 0.6 undecidable manual S 248 4.8951 138 -0.01 50
IT.MOG.HNZ. 2023-09-20T10:02:23.57 0.1 undecidable manual P 40 13.0758 112 0.01 99
IV.LMD.HHZ. 2023-09-20T10:02:22.74 0.6 undecidable manual S 95 3.7962 145 -0.27 48
IT.MRR.HGZ. 2023-09-20T10:02:22.15 0.1 undecidable manual P 248 4.8951 138 -0.03 100
IV.LMD.HHZ. 2023-09-20T10:02:21.80 1.0 undecidable manual P 95 3.7962 145 -0.24 24
Station Magnitude and Amplitude
SCNL mag Generic_amplitude Period Type Category Unit Time_window_reference
IV.VMGN.HHE. ML:0.4 0.0000265 1.16 AML other m 2023-09-20T10:02:27.96
IV.VISG.HHE. ML:0.5 0.0000249 0.64 AML other m 2023-09-20T10:02:29.37
IV.VMGN.HHN. ML:0.5 0.00002987252 0.3584 AML other m 2023-09-20T10:02:29.40
IV.VISG.HHN. ML:0.6 0.0000314 1.1 AML other m 2023-09-20T10:02:29.09
IV.LMD.HHE. ML:0.0 0.0002473174 0.096 AML other m 2023-09-20T10:02:23.74
IV.LMD.HHN. ML:0.0 0.0005573620500000001 0.1984 AML other m 2023-09-20T10:02:22.83
IV.RINC.EHE. ML:0.7 0.000035269355 0.1216 AML other m 2023-09-20T10:02:29.02
IV.RINC.EHN. ML:0.7 0.00003344064 0.5376 AML other m 2023-09-20T10:02:33.20
IV.RUFI.EHE. ML:0.3 0.0000087258505 0.2624 AML other m 2023-09-20T10:02:35.83
IV.RUFI.EHN. ML:0.6 0.000020346795 0.16 AML other m 2023-09-20T10:02:31.21
TDMT - Time Domain Moment Tensor
Fault Plane solutions in the area
Download
Type Description Link
QuakeML - small Event, Origin, FocalMechanism Download
QuakeML - full Event, Origin, FocalMechanism, Amplitude, Arrival, Pick, Station Magnitude Download