Istituto Nazionale di Geofisica e Vulcanologia

Earthquake with magnitude of ML 1.6 on date 18-08-2021 and time 20:35:02 (Italy) in region 4 km N Colonna (RM)

A magnitude ML 1.6 earthquake occured in region: 4 km N Colonna (RM), on

  • 18-08-2021 18:35:02 (UTC)
  • 18-08-2021 20:35:02 (UTC +02:00) Italian time

and geographic coordinates (lat, lon) 41.8730, 12.7550 at 10 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
Colonna RM 4 4287 4287
Gallicano nel Lazio RM 6 6334 10621
San Cesareo RM 7 15153 25774
Monte Porzio Catone RM 7 8693 34467
Zagarolo RM 7 17843 52310
Monte Compatri RM 7 11978 64288
Rocca Priora RM 9 11962 76250
Frascati RM 10 22087 98337
Tivoli RM 11 56533 154870
San Gregorio da Sassola RM 11 1619 156489
Casape RM 12 744 157233
Poli RM 12 2418 159651
Palestrina RM 12 21672 181323
Grottaferrata RM 12 20327 201650
Castel San Pietro Romano RM 12 902 202552
Rocca di Papa RM 13 17034 219586
Marino RM 14 43026 262612
Guidonia Montecelio RM 14 88673 351285
Labico RM 15 6379 357664
Ciampino RM 15 38412 396076
Castel Madama RM 15 7399 403475
Cave RM 16 11287 414762
Rocca di Cave RM 16 377 415139
Castel Gandolfo RM 16 8997 424136
Capranica Prenestina RM 16 351 424487
San Polo dei Cavalieri RM 17 2992 427479
Valmontone RM 17 15959 443438
Nemi RM 17 1943 445381
Lariano RM 17 13432 458813
Marcellina RM 17 7280 466093
Pisoniano RM 17 770 466863
Albano Laziale RM 18 41715 508578
Fonte Nuova RM 18 32562 541140
Ariccia RM 18 19407 560547
Sant'Angelo Romano RM 18 5018 565565
Ciciliano RM 18 1336 566901
Genazzano RM 19 6036 572937
San Vito Romano RM 19 3273 576210
Genzano di Roma RM 19 23970 600180
Vicovaro RM 20 4019 604199
Sambuci RM 20 925 605124
Artena RM 20 14276 619400

Municipalities with at least 50000 inhabitants

An earthquake occurred to
11 Km SW of Tivoli (56533 inhabitants)
14 Km S of Guidonia Montecelio (88673 inhabitants)
21 Km N of Velletri (53303 inhabitants)
23 Km E of Roma (2864731 inhabitants)
31 Km NE of Pomezia (62966 inhabitants)
32 Km N of Aprilia (73446 inhabitants)
44 Km E of Fiumicino (78395 inhabitants)
47 Km N of Latina (125985 inhabitants)
48 Km N of Anzio (54211 inhabitants)
75 Km SW of L'Aquila (69753 inhabitants)
77 Km S of Terni (111501 inhabitants)
81 Km SE of Viterbo (67173 inhabitants)
83 Km E of Civitavecchia (52991 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 1.6 2021-08-18
18:35:02		 41.8732 12.7552 10 2021-12-29
11:12:27		 Bollettino Sismico Italiano INGV 95148271
Reviewed
Rev100 		ML 2.2 2021-08-18
18:35:02		 41.8698 12.7618 10 2021-08-18
18:50:36		 Sala Sismica INGV-Roma 94342851
Preferred location and magnitude until now.
Origin information

Origin

Field Value
Time (UTC) 2021-08-18 18:35:02 ± 0.06
Latitude 41.8732 ± 0.0027
Longitude 12.7552 ± 0.0048
Depth (km) 10 ± 0 (from location)
Evaluation mode of Origin manual
Evaluation status of Origin reviewed
Version 1000 -> BULLETIN-INGV
Event type earthquake
Origin ID 95148271

Uncertainty

Field Value
Preferred uncertainty description uncertainty ellipse
Semi-major axis of confidence ellipse (meter) 410
Semi-minor axis of confidence ellipse (meter) 264
Azimuth of major axis of confidence ellipse. Measured clockwise from South-North direction at epicenter (gradi) 282
Circular confidence region, given by single value of horizontal uncertainty (meter) 410.0
Confidence level of the uncertainty (%) 68

Quality

Field Value
Largest azimuthal gap in station distribution as seen from epicenter (degree) 91
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) 0.21
Epicentral distance of station closest to the epicenter (degree) 0.07195
Epicentral distance of station farthest from the epicenter (degree) 0.64302
Number of stations at which the event was observed 14
Number of stations from which data was used for origin computation 14
Magnitudes information

ML:2.2

Field Value
Value 2.2
Uncertainty 0.4
Num. used stations 10
Type of magnitude ML
Reference to an origin 94342851
Agency INGV
Autore Sala Sismica INGV-Roma
Time of creation (UTC) 2021-08-18 18:50:36

ML:1.6

Field Value
Value 1.6
Uncertainty 0.4
Num. used stations 14
Type of magnitude ML
Reference to an origin 95148271
Agency INGV
Autore Bollettino Sismico Italiano INGV
Time of creation (UTC) 2021-12-10 14:17:43
Picking and Arrival
SCNL Time Uncertainty Polarity Evaluation_mode Phase Azimuth Distance(km) Takeoff_angle Residual Weight
IV.GIUL.HHZ. 2021-08-18T18:35:20.12 0.3 undecidable manual S 130 54.1014 50 0.69 59
IV.PTQR.HHZ. 2021-08-18T18:35:20.21 0.6 undecidable manual S 73 55.6998 50 0.35 44
IV.LATB.EHZ. 2021-08-18T18:35:16.90 0.6 undecidable manual S 158 45.4212 50 -0.21 46
IV.BARO.HNZ. 2021-08-18T18:35:14.48 0.3 undecidable manual P 306 71.373 50 -0.33 64
IV.PTQR.HHZ. 2021-08-18T18:35:12.17 0.3 undecidable manual P 73 55.6998 50 -0.23 67
IV.FIAM.HNN. 2021-08-18T18:35:11.87 0.3 undecidable manual P 34 53.0025 50 -0.11 69
IV.GIUL.HHZ. 2021-08-18T18:35:11.84 0.3 undecidable manual P 130 54.1014 50 -0.31 66
IV.LAV9.HNZ. 2021-08-18T18:35:10.90 0.3 undecidable manual S 192 22.1556 114 0.3 70
IV.LATB.EHZ. 2021-08-18T18:35:10.59 0.3 undecidable manual P 158 45.4212 50 -0.22 69
IV.SRES.HHN. 2021-08-18T18:35:10.70 0.3 undecidable manual P 333 45.1215 50 -0.06 71
IV.MTCE.HHZ. 2021-08-18T18:35:09.10 0.3 undecidable manual S 356 16.6722 120 0.22 72
IV.CERT.HHZ. 2021-08-18T18:35:09.88 0.3 undecidable manual S 66 20.4684 115 -0.19 72
IV.MA9.HHZ. 2021-08-18T18:35:08.00 0.3 undecidable manual S 215 13.9749 125 -0.1 74
IV.RCAV.EHZ. 2021-08-18T18:35:08.50 0.3 undecidable manual S 100 15.9729 121 -0.19 73
IV.VIVA.HHZ. 2021-08-18T18:35:07.80 0.3 undecidable manual S 175 13.6752 125 -0.23 72
IV.RDP.HHZ. 2021-08-18T18:35:07.70 0.3 undecidable manual S 197 13.0758 126 -0.14 74
IV.LAV9.HNZ. 2021-08-18T18:35:07.28 0.3 undecidable manual P 192 22.1556 114 0.22 71
IV.RCAV.EHZ. 2021-08-18T18:35:06.05 0.3 undecidable manual P 100 15.9729 121 0.1 74
IV.CERT.HHZ. 2021-08-18T18:35:06.69 0.3 undecidable manual P 66 20.4684 115 -0.06 74
IV.RMP.HHZ. 2021-08-18T18:35:06.40 0.3 undecidable manual S 211 7.9809 140 -0.16 74
IV.MTCE.HHZ. 2021-08-18T18:35:06.27 0.1 negative manual P 356 16.6722 120 0.21 97
IV.VIVA.HHZ. 2021-08-18T18:35:05.70 0.3 undecidable manual P 175 13.6752 125 0.14 74
IV.MA9.HHZ. 2021-08-18T18:35:05.51 0.3 undecidable manual P 215 13.9749 125 -0.1 74
IV.RDP.HHZ. 2021-08-18T18:35:05.77 0.3 undecidable manual P 197 13.0758 126 0.31 71
IV.RMP.HHZ. 2021-08-18T18:35:04.83 0.1 undecidable manual P 211 7.9809 140 0.11 100
Station Magnitude and Amplitude
SCNL mag Generic_amplitude Period Type Category Unit Time_window_reference
IV.RMP.HHE. ML:2.6 0.006285 0.4 AML other m 2021-08-18T18:35:06.77
IV.RMP.HHN. ML:2.6 0.0057978945 0.4224 AML other m 2021-08-18T18:35:06.92
IV.RDP.HHE. ML:1.8 0.0007077535500000001 1.1648 AML other m 2021-08-18T18:35:08.25
IV.VIVA.HHN. ML:2.0 0.0010238587000000001 0.5632 AML other m 2021-08-18T18:35:08.12
IV.RDP.HHN. ML:2.1 0.00140853875 0.3328 AML other m 2021-08-18T18:35:08.20
IV.VIVA.HHE. ML:1.9 0.0009201509999999999 0.448 AML other m 2021-08-18T18:35:08.44
IV.MTCE.HHN. ML:1.5 0.00030100000000000005 0.28 AML other m 2021-08-18T18:35:09.49
IV.MTCE.HHE. ML:1.5 0.00028050000000000004 0.42 AML other m 2021-08-18T18:35:09.62
IV.CERT.HHN. ML:1.2 0.000131122045 0.0896 AML other m 2021-08-18T18:35:10.25
IV.CERT.HHE. ML:1.5 0.0002433518 0.576 AML other m 2021-08-18T18:35:10.39
IV.LATB.EHN. ML:0.9 0.000026335005 2.304 AML other m 2021-08-18T18:35:17.26
IV.LATB.EHE. ML:1.1 0.000036823795 0.3584 AML other m 2021-08-18T18:35:17.55
IV.GIUL.HHE. ML:1.1 0.000027934855000000003 3.2256 AML other m 2021-08-18T18:35:20.33
IV.GIUL.HHN. ML:1.0 0.000026624785000000002 0.4992 AML other m 2021-08-18T18:35:20.56
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
Waveforms Seismic signals in miniseed + resp format Download