Earthquake with magnitude of ML 0.6 on date 18-09-2021 and time 20:39:23 (UTC) in region 6 km S Montieri (GR)

A magnitude ML 0.6 earthquake occured in region: 6 km S Montieri (GR), on

  • 18-09-2021 20:39:23 (UTC)
  • 18-09-2021 22:39:23 (UTC +02:00) Italian time

and geographic coordinates (lat, lon) 43.078, 11.013 at 10 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.

Municipalities within 20 km from the epicenter

Distances are determinated based on the geographic coordintes of the (Istat).
Municipality Region Dist Inh Cum Inh
Montieri GR 6 1204 1204
Massa Marittima GR 11 8375 9579
Chiusdino SI 11 1903 11482
Roccastrada GR 15 9199 20681
Monterotondo Marittimo GR 15 1371 22052
Monticiano SI 15 1571 23623
Castelnuovo di Val di Cecina PI 17 2231 25854
Gavorrano GR 19 8580 34434

Municipalities with at least 50000 inhabitants

An earthquake occurred to
36 Km N of Grosseto (82087 inhabitants)
37 Km SW of Siena (53903 inhabitants)
77 Km S of Scandicci (50609 inhabitants)
78 Km SE of Livorno (159219 inhabitants)
79 Km S of Firenze (382808 inhabitants)
83 Km SW of Arezzo (99543 inhabitants)
86 Km SE of Pisa (89158 inhabitants)
90 Km S of Prato (191150 inhabitants)
95 Km SE of Lucca (89046 inhabitants)
96 Km S of Pistoia (90315 inhabitants)
Recent and historical seismicity
Seismic hazard
Felt maps
Preliminary map of the earthquake effects from the web questionnaire

Preliminary map of the earthquake effects from the web questionnaire

This map shows the distribution of the effects of the earthquake on the territory in terms of the MCS (Mercalli-Cancani-Sieberg) intensity scale. The intensities are determined using the data provided in the questionnaire ( that are analysed using robust statistical techniques since they are not verified individually. Specifically, the assignment of MCS intensities greater or equal the VI degree of the MCS scale require opportune in situ verification by professional experts. The purple start shows the epicenter. This map is prepared every so often that the population fill in new questionnaires. The number of questionnaires used to determine the map and the date and time of the last adjournment are shown in the upper right part of the panel.
Locations history
Type Magnitude Date and Time (UTC) Latitude Longitude Depth (km) Published time (UTC) Author Location ID
ML 0.6 2021-09-18
43.0782 11.0127 11 2021-09-18
Sala Sismica INGV-Roma 95600791
Preferred location and magnitude until now.
Origin information


Field Value
Time (UTC) 2021-09-18 20:39:23 ± 0.18
Latitude 43.0782 ± 0.0090
Longitude 11.0127 ± 0.0148
Depth (km) 11 ± 1 (from location)
Evaluation mode of Origin manual
Evaluation status of Origin reviewed
Version 100 -> SURVEY-INGV
Event type earthquake
Origin ID 95600791


Field Value
Preferred uncertainty description uncertainty ellipse
Semi-major axis of confidence ellipse (meter) 1095
Semi-minor axis of confidence ellipse (meter) 971
Azimuth of major axis of confidence ellipse. Measured clockwise from South-North direction at epicenter (gradi) 81
Circular confidence region, given by single value of horizontal uncertainty (meter) 1100
Confidence level of the uncertainty (%) 68


Field Value
Largest azimuthal gap in station distribution as seen from epicenter (degree) 131
Number of associated phases, regardless of their use for origin computation 8
Number of defining phases 8
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) 0.08813
Epicentral distance of station farthest from the epicenter (degree) 0.30667
Number of stations at which the event was observed 4
Number of stations from which data was used for origin computation 4
Magnitude information


Field Value
Value 0.6
Uncertainty 0.1
Num. used stations 2
Type of magnitude ML
Reference to an origin 95600791
Agency INGV
Autore Sala Sismica INGV-Roma
Time of creation (UTC) 2021-09-18 20:43:45
Picking and Arrival
SCNL Time Uncertainty Polarity Evaluation_mode Phase Azimuth Distance Takeoff_angle Residual Weight
IV.CASP.HHZ. 2021-09-18T20:39:35.15 0.3 undecidable manual S 201 0.3067 50 -0.41 68
IV.CASP.HHZ. 2021-09-18T20:39:30.93 0.3 undecidable manual P 201 0.3067 50 0.31 70
IV.FROS.CHZ. 2021-09-18T20:39:30.91 0.6 undecidable manual S 38 0.1682 119 -0.39 47
IV.RIBO.EHZ.01 2021-09-18T20:39:29.91 0.6 undecidable manual S 169 0.1313 126 -0.2 49
IV.TRIF.CHZ. 2021-09-18T20:39:28.53 0.3 undecidable manual S 295 0.0881 137 -0.32 72
IV.FROS.CHZ. 2021-09-18T20:39:28.24 0.1 undecidable manual P 38 0.1682 119 0.08 100
IV.TRIF.CHZ. 2021-09-18T20:39:27.07 0.1 undecidable manual P 295 0.0881 137 0.32 97
IV.RIBO.EHZ.01 2021-09-18T20:39:27.66 0.1 undecidable manual P 169 0.1313 126 0.18 99
Station Magnitude and Amplitude
SCNL mag Generic_amplitude Period Type Category Unit Time_window_reference
IV.TRIF.CHN. ML:0.6 4.53E-5 0.44 AML other m 2021-09-18T20:39:29.13
IV.TRIF.CHE. ML:0.6 5.435E-5 0.16 AML other m 2021-09-18T20:39:29.83
IV.FIR.HHE. ML:2.2 0.000244 0.06 AML other m 2021-09-18T20:39:42.92
IV.FIR.HHN. ML:2.3 0.000252 1.36 AML other m 2021-09-18T20:39:55.98
TDMT - Time Domain Moment Tensor
Fault Plane solutions in the area
Type Description Link
QuakeML - small Event, Origin, FocalMechanism Download
QuakeML - full Event, Origin, FocalMechanism, Amplitude, Arrival, Pick, Station Magnitude Download