Istituto Nazionale di Geofisica e Vulcanologia

Earthquake with magnitude of ML 1.0 on date 20-04-2023 and time 16:34:57 (UTC) in region 4 km NE San Gemini (TR)

A magnitude ML 1.0 earthquake occured in region: 4 km NE San Gemini (TR), on

  • 20-04-2023 16:34:57 (UTC)
  • 20-04-2023 18:34:57 (UTC +02:00) Italian time

and geographic coordinates (lat, lon) 42.6430, 12.5740 at 8 km depth.

The earthquake was located by: Bollettino Sismico Italiano INGV.

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
San Gemini TR 4 5018 5018
Acquasparta TR 6 4778 9796
Montecastrilli TR 7 5022 14818
Terni TR 11 111501 126319
Avigliano Umbro TR 12 2558 128877
Narni TR 15 19785 148662
Massa Martana PG 15 3770 152432
Amelia TR 16 11897 164329
Montefranco TR 17 1276 165605
Spoleto PG 17 38218 203823
Arrone TR 17 2763 206586
Stroncone TR 18 4917 211503
Ferentillo TR 18 1913 213416

Municipalities with at least 50000 inhabitants

An earthquake occurred to
11 Km NW of Terni (111501 inhabitants)
37 Km SW of Foligno (57155 inhabitants)
46 Km NE of Viterbo (67173 inhabitants)
54 Km S of Perugia (166134 inhabitants)
73 Km N of Guidonia Montecelio (88673 inhabitants)
75 Km W of L'Aquila (69753 inhabitants)
78 Km N of Tivoli (56533 inhabitants)
84 Km N of Roma (2864731 inhabitants)
89 Km NE of Civitavecchia (52991 inhabitants)
93 Km W of Teramo (54892 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
Bulletin
Rev1000 		ML 1.0 2023-04-20
16:34:57		 42.6432 12.5738 8 2024-03-01
17:18:20		 Bollettino Sismico Italiano INGV 124871631
Reviewed
Rev100 		ML 1.1 2023-04-20
16:34:56		 42.6085 12.5713 8 2023-04-20
16:55:18		 Sala Sismica INGV-Roma 116555791
Preferred location and magnitude until now.
Origin information

Origin

Field Value
Time (UTC) 2023-04-20 16:34:57 ± 0.16
Latitude 42.6432 ± 0.0081
Longitude 12.5738 ± 0.0110
Depth (km) 8 ± 1 (from location)
Evaluation mode of Origin manual
Evaluation status of Origin reviewed
Version 1000 -> BULLETIN-INGV
Event type earthquake
Origin ID 124871631

Uncertainty

Field Value
Preferred uncertainty description uncertainty ellipse
Semi-major axis of confidence ellipse (meter) 1013
Semi-minor axis of confidence ellipse (meter) 709
Azimuth of major axis of confidence ellipse. Measured clockwise from South-North direction at epicenter (gradi) 219
Circular confidence region, given by single value of horizontal uncertainty (meter) 1010.0
Confidence level of the uncertainty (%) 68

Quality

Field Value
Largest azimuthal gap in station distribution as seen from epicenter (degree) 144
Number of associated phases, regardless of their use for origin computation 25
Number of defining phases 25
RMS of the travel time residuals of the arrivals used for the origin computation (sec) 0.34
Epicentral distance of station closest to the epicenter (degree) 0.03597
Epicentral distance of station farthest from the epicenter (degree) 0.78691
Number of stations at which the event was observed 13
Number of stations from which data was used for origin computation 13
Magnitudes information

ML:1.0

Field Value
Value 1.0
Uncertainty 0.2
Num. used stations 12
Type of magnitude ML
Reference to an origin 124871631
Agency INGV
Autore Bollettino Sismico Italiano INGV
Time of creation (UTC) 2024-01-26 14:11:21

ML:1.1

Field Value
Value 1.1
Uncertainty 0.2
Num. used stations 12
Type of magnitude ML
Reference to an origin 116555791
Agency INGV
Autore Sala Sismica INGV-Roma
Time of creation (UTC) 2023-04-20 16:55:18
Picking and Arrival
SCNL Time Uncertainty Polarity Evaluation_mode Phase Azimuth Distance(km) Takeoff_angle Residual Weight
IV.EL6.EHZ. 2023-04-20T16:35:25.47 0.6 undecidable manual S 29 87.3459 50 1.43 25
IV.CSP1.EHZ. 2023-04-20T16:35:20.10 0.6 undecidable manual S 46 71.4729 50 0.3 42
IV.FDMO.HHZ. 2023-04-20T16:35:17.01 0.3 undecidable manual S 44 60.3951 50 0.16 66
IV.MGAB.HHZ. 2023-04-20T16:35:14.16 0.6 undecidable manual S 309 48.0186 50 0.62 40
IV.NRCA.HHZ. 2023-04-20T16:35:13.50 0.6 undecidable manual S 64 48.8178 50 -0.26 44
IV.CESI.HHZ. 2023-04-20T16:35:13.66 0.6 undecidable manual S 34 48.3183 50 0.04 46
IV.EL6.EHZ. 2023-04-20T16:35:12.66 0.3 undecidable manual P 29 87.3459 50 -0.21 62
IV.ASSB.HHZ. 2023-04-20T16:35:12.60 0.6 undecidable manual S 9 44.8218 50 -0.09 46
IV.CSP1.EHZ. 2023-04-20T16:35:10.08 0.3 undecidable manual P 46 71.4729 50 -0.34 63
IV.FDMO.HHZ. 2023-04-20T16:35:08.30 0.1 undecidable manual P 44 60.3951 50 -0.41 84
IV.NRCA.HHZ. 2023-04-20T16:35:06.29 0.3 undecidable manual P 64 48.8178 50 -0.64 60
IV.GAVE.EHN. 2023-04-20T16:35:06.87 0.6 undecidable manual S 78 26.6511 107 -0.41 45
IV.CESI.HHZ. 2023-04-20T16:35:06.43 0.3 undecidable manual P 34 48.3183 50 -0.42 64
IV.LNSS.HHZ. 2023-04-20T16:35:06.00 0.3 undecidable manual P 97 38.3283 50 0.69 60
IV.MGAB.HHZ. 2023-04-20T16:35:06.88 0.3 undecidable manual P 309 48.0186 50 0.07 69
IV.ASSB.HHZ. 2023-04-20T16:35:05.95 0.3 undecidable manual P 9 44.8218 50 -0.37 65
IV.ARRO.EHZ. 2023-04-20T16:35:04.97 0.6 undecidable manual S 114 17.1717 115 0.77 40
IT.GNU.HGE. 2023-04-20T16:35:04.74 0.6 undecidable manual S 359 17.871 114 0.34 46
IV.MOMA.HHZ. 2023-04-20T16:35:04.73 0.6 undecidable manual S 359 17.871 114 0.33 46
IV.GAVE.EHN. 2023-04-20T16:35:03.17 0.3 undecidable manual P 78 26.6511 107 -0.02 73
IV.ARRO.EHZ. 2023-04-20T16:35:02.04 0.3 undecidable manual P 114 17.1717 115 0.63 63
IT.GNU.HGE. 2023-04-20T16:35:01.44 0.3 undecidable manual P 359 17.871 114 -0.08 73
IV.MOMA.HHZ. 2023-04-20T16:35:01.44 0.1 positive manual P 359 17.871 114 -0.09 97
IV.CESX.HHZ. 2023-04-20T16:35:00.22 0.6 undecidable manual S 165 3.996 154 -0.51 45
IV.CESX.HHZ. 2023-04-20T16:34:59.36 0.1 undecidable manual P 165 3.996 154 -0.05 100
Station Magnitude and Amplitude
SCNL mag Generic_amplitude Period Type Category Unit Time_window_reference
IV.ARRO.EHN. ML:1.1 0.000112 1.66 AML other m 2023-04-20T16:35:06.92
IV.MOMA.HHE. ML:1.2 0.000142 1.4 AML other m 2023-04-20T16:35:06.81
IV.ARRO.EHE. ML:1.0 0.0000926 0.74 AML other m 2023-04-20T16:35:06.41
IV.MOMA.HHN. ML:1.0 0.00008215 1.08 AML other m 2023-04-20T16:35:06.11
IV.CESI.HHN. ML:1.0 0.00002325 0.56 AML other m 2023-04-20T16:35:14.58
IV.CESI.HHE. ML:0.9 0.0000185 0.58 AML other m 2023-04-20T16:35:14.60
IV.ASSB.HHE. ML:1.0 0.000027700000000000002 0.32 AML other m 2023-04-20T16:35:15.41
IV.NRCA.HHE. ML:1.1 0.000037099999999999994 0.38 AML other m 2023-04-20T16:35:15.62
IV.MGAB.HHE. ML:1.3 0.0000494 1.02 AML other m 2023-04-20T16:35:15.96
IV.MGAB.HHN. ML:1.2 0.000037749999999999996 1.42 AML other m 2023-04-20T16:35:16.16
IV.NRCA.HHN. ML:1.0 0.000026700000000000002 0.92 AML other m 2023-04-20T16:35:16.73
IV.ASSB.HHN. ML:0.7 0.0000161 0.46 AML other m 2023-04-20T16:35:18.00
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