Earthquake with magnitude of ML 0.9 on date 18-09-2021 and time 23:52:11 (Italy) in region 3 km NE Montieri (GR)

A magnitude ML 0.9 earthquake occured in region: 3 km NE Montieri (GR), on

  • 18-09-2021 21:52:11 (UTC)
  • 18-09-2021 23:52:11 (UTC +02:00) Italian time

and geographic coordinates (lat, lon) 43.156, 11.035 at 0 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 3 1204 1204
Chiusdino SI 4 1903 3107
Radicondoli SI 12 914 4021
Monticiano SI 12 1571 5592
Castelnuovo di Val di Cecina PI 12 2231 7823
Monterotondo Marittimo GR 15 1371 9194
Massa Marittima GR 17 8375 17569
Roccastrada GR 19 9199 26768

Municipalities with at least 50000 inhabitants

An earthquake occurred to
30 Km SW of Siena (53903 inhabitants)
44 Km N of Grosseto (82087 inhabitants)
68 Km S of Scandicci (50609 inhabitants)
71 Km S of Firenze (382808 inhabitants)
73 Km SE of Livorno (159219 inhabitants)
77 Km W of Arezzo (99543 inhabitants)
81 Km SE of Pisa (89158 inhabitants)
81 Km S of Prato (191150 inhabitants)
87 Km S of Pistoia (90315 inhabitants)
88 Km SE of Lucca (89046 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 0.9 2021-09-18
43.1563 11.0352 1 2021-09-18
Sala Sismica INGV-Roma 95603271
Preferred location and magnitude until now.
Origin information


Field Value
Time (UTC) 2021-09-18 21:52:11 ± 0.02
Latitude 43.1563 ± 0.0009
Longitude 11.0352 ± 0.0012
Depth (km) 1 (operator assigned)
Evaluation mode of Origin manual
Evaluation status of Origin reviewed
Version 100 -> SURVEY-INGV
Event type earthquake
Origin ID 95603271


Field Value
Preferred uncertainty description uncertainty ellipse
Semi-major axis of confidence ellipse (meter) 600
Semi-minor axis of confidence ellipse (meter) 120
Azimuth of major axis of confidence ellipse. Measured clockwise from South-North direction at epicenter (gradi) 235
Circular confidence region, given by single value of horizontal uncertainty (meter) 120
Confidence level of the uncertainty (%) 68


Field Value
Largest azimuthal gap in station distribution as seen from epicenter (degree) 172
Number of associated phases, regardless of their use for origin computation 7
Number of defining phases 6
RMS of the travel time residuals of the arrivals used for the origin computation (sec) 0.03
Epicentral distance of station closest to the epicenter (degree) 0
Epicentral distance of station farthest from the epicenter (degree) 0.20774
Number of stations at which the event was observed 4
Number of stations from which data was used for origin computation 3
Magnitude information


Field Value
Value 0.9
Uncertainty 0.1
Num. used stations 4
Type of magnitude ML
Reference to an origin 95603271
Agency INGV
Autore Sala Sismica INGV-Roma
Time of creation (UTC) 2021-09-18 22:02:42
Picking and Arrival
SCNL Time Uncertainty Polarity Evaluation_mode Phase Azimuth Distance Takeoff_angle Residual Weight
IV.CASP.HHZ. 2021-09-18T21:52:19.22 3.0 undecidable manual P 0 0
IV.RIBO.EHZ.01 2021-09-18T21:52:19.11 0.3 undecidable manual S 178 0.2077 91 -0.02 73
IV.RIBO.EHZ.01 2021-09-18T21:52:15.79 0.3 undecidable manual P 178 0.2077 91 0.04 73
IV.FROS.CHZ. 2021-09-18T21:52:15.12 0.1 undecidable manual S 59 0.1034 92 0 100
IV.TRIF.CHZ. 2021-09-18T21:52:15.18 0.1 undecidable manual S 247 0.1052 92 -0.02 100
IV.FROS.CHZ. 2021-09-18T21:52:13.42 0.1 undecidable manual P 59 0.1034 92 -0.01 100
IV.TRIF.CHZ. 2021-09-18T21:52:13.51 0.1 undecidable manual P 247 0.1052 92 0.03 100
Station Magnitude and Amplitude
SCNL mag Generic_amplitude Period Type Category Unit Time_window_reference
IV.FROS.CHE. ML:1.1 0.0001855 0.64 AML other m 2021-09-18T21:52:15.20
IV.FROS.CHN. ML:0.9 0.0001205 0.72 AML other m 2021-09-18T21:52:15.66
IV.TRIF.CHN. ML:0.8 0.00010195 1.28 AML other m 2021-09-18T21:52:16.00
IV.TRIF.CHE. ML:0.8 0.00010095 1.52 AML other m 2021-09-18T21:52:16.95
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