Istituto Nazionale di Geofisica e Vulcanologia

Earthquake with magnitude of ML 0.8 on date 21-04-2021 and time 09:34:35 (Italy) in region 7 km SW Roccastrada (GR)

A magnitude ML 0.8 earthquake occured in region: 7 km SW Roccastrada (GR), on

  • 21-04-2021 07:34:35 (UTC)
  • 21-04-2021 09:34:35 (UTC +02:00) Italian time

and geographic coordinates (lat, lon) 42.9530, 11.1380 at 9 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
Roccastrada GR 7 9199 9199
Civitella Paganico GR 13 3154 12353
Campagnatico GR 14 2412 14765
Gavorrano GR 19 8580 23345

Municipalities with at least 50000 inhabitants

An earthquake occurred to
21 Km N of Grosseto (82087 inhabitants)
44 Km SW of Siena (53903 inhabitants)
83 Km SW of Arezzo (99543 inhabitants)
90 Km S of Scandicci (50609 inhabitants)
91 Km S of Firenze (382808 inhabitants)
95 Km SE of Livorno (159219 inhabitants)
99 Km NW of Viterbo (67173 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 0.8 2021-04-21
07:34:35		 42.9528 11.1377 9 2021-07-12
16:55:11		 Bollettino Sismico Italiano INGV 90228631
Reviewed
Rev100 		ML 1.0 2021-04-21
07:34:35		 42.9538 11.1177 11 2021-04-21
07:43:00		 Sala Sismica INGV-Roma 89320841
Preferred location and magnitude until now.
Origin information

Origin

Field Value
Time (UTC) 2021-04-21 07:34:35 ± 0.15
Latitude 42.9528 ± 0.0090
Longitude 11.1377 ± 0.0135
Depth (km) 9 ± 2 (from location)
Evaluation mode of Origin manual
Evaluation status of Origin reviewed
Version 1000 -> BULLETIN-INGV
Event type earthquake
Origin ID 90228631

Uncertainty

Field Value
Preferred uncertainty description uncertainty ellipse
Semi-major axis of confidence ellipse (meter) 1026
Semi-minor axis of confidence ellipse (meter) 865
Azimuth of major axis of confidence ellipse. Measured clockwise from South-North direction at epicenter (gradi) 19
Circular confidence region, given by single value of horizontal uncertainty (meter) 1030.0
Confidence level of the uncertainty (%) 68

Quality

Field Value
Largest azimuthal gap in station distribution as seen from epicenter (degree) 112
Number of associated phases, regardless of their use for origin computation 14
Number of defining phases 14
RMS of the travel time residuals of the arrivals used for the origin computation (sec) 0.46
Epicentral distance of station closest to the epicenter (degree) 0.06655
Epicentral distance of station farthest from the epicenter (degree) 0.40110
Number of stations at which the event was observed 7
Number of stations from which data was used for origin computation 7
Magnitudes information

ML:1.0

Field Value
Value 1.0
Uncertainty 0.3
Num. used stations 9
Type of magnitude ML
Reference to an origin 89320841
Agency INGV
Autore Sala Sismica INGV-Roma
Time of creation (UTC) 2021-04-21 07:43:00

ML:0.8

Field Value
Value 0.8
Uncertainty 0.4
Num. used stations 9
Type of magnitude ML
Reference to an origin 90228631
Agency INGV
Autore Bollettino Sismico Italiano INGV
Time of creation (UTC) 2021-05-18 12:12:04
Picking and Arrival
SCNL Time Uncertainty Polarity Evaluation_mode Phase Azimuth Distance(km) Takeoff_angle Residual Weight
TV.SF14.HHN. 2021-04-21T07:34:50.19 0.6 undecidable manual S 119 44.5221 50 -0.34 46
TV.SF04.EHZ. 2021-04-21T07:34:49.73 0.3 undecidable manual S 107 44.4222 50 -0.76 60
IV.FROS.CHZ. 2021-04-21T07:34:46.08 0.3 undecidable manual S 3 28.5492 107 -0.01 76
IV.CASP.HHZ. 2021-04-21T07:34:45.28 0.3 undecidable manual S 231 28.5492 107 -0.81 61
IV.ARCI.HHZ. 2021-04-21T07:34:45.89 0.3 undecidable manual S 112 29.6481 107 -0.57 67
TV.SF04.EHZ. 2021-04-21T07:34:44.66 0.1 undecidable manual P 107 44.4222 50 0.41 90
TV.SF14.HHN. 2021-04-21T07:34:44.78 0.1 undecidable manual P 119 44.5221 50 0.51 88
IV.TRIF.CHZ. 2021-04-21T07:34:44.44 0.3 undecidable manual S 313 26.1516 109 -0.88 59
IV.ARCI.HHZ. 2021-04-21T07:34:42.20 0.1 undecidable manual P 112 29.6481 107 0.28 96
IV.CASP.HHZ. 2021-04-21T07:34:42.02 0.1 undecidable manual P 231 28.5492 107 0.32 95
IV.TRIF.CHZ. 2021-04-21T07:34:41.58 0.1 undecidable manual P 313 26.1516 109 0.32 95
IV.FROS.CHZ. 2021-04-21T07:34:41.63 0.1 undecidable manual P 3 28.5492 107 -0.07 100
IV.RIBO.EHZ.01 2021-04-21T07:34:39.88 0.3 undecidable manual S 267 7.3815 140 0.13 77
IV.RIBO.EHZ.01 2021-04-21T07:34:38.33 0.1 undecidable manual P 267 7.3815 140 0.28 99
Station Magnitude and Amplitude
SCNL mag Generic_amplitude Period Type Category Unit Time_window_reference
IV.RIBO.EHE.01 ML:0.9 0.00012879970000000002 0.1024 AML other m 2021-04-21T07:34:40.45
IV.CASP.HHE. ML:0.0 0.0000058567274999999996 0.4224 AML other m 2021-04-21T07:34:45.33
IV.CASP.HHN. ML:0.0 0.0000045908051000000004 0.32 AML other m 2021-04-21T07:34:45.59
IV.ARCI.HHN. ML:0.5 0.000013352075 0.2432 AML other m 2021-04-21T07:34:46.49
IV.FROS.CHE. ML:1.0 0.00005215 0.26 AML other m 2021-04-21T07:34:46.73
IV.ARCI.HHE. ML:0.5 0.000016405045 0.1984 AML other m 2021-04-21T07:34:46.81
IV.FROS.CHN. ML:0.9 0.000043277650000000004 1.7312 AML other m 2021-04-21T07:34:47.02
TV.SF04.EHN. ML:1.1 0.000034510065 0.1408 AML other m 2021-04-21T07:34:50.42
TV.SF04.EHE. ML:1.0 0.000029908143 0.704 AML other m 2021-04-21T07:34:50.69
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