Earthquake with magnitude of ML 0.4 on date 18-09-2021 and time 22:45:30 (Italy) in region 5 km E Massa Marittima (GR)

A magnitude ML 0.4 earthquake occured in region: 5 km E Massa Marittima (GR), on

  • 18-09-2021 20:45:30 (UTC)
  • 18-09-2021 22:45:30 (UTC +02:00) Italian time

and geographic coordinates (lat, lon) 43.044, 10.955 at 5 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
Massa Marittima GR 5 8375 8375
Montieri GR 11 1204 9579
Gavorrano GR 14 8580 18159
Monterotondo Marittimo GR 14 1371 19530
Chiusdino SI 17 1903 21433
Scarlino GR 17 3847 25280
Roccastrada GR 18 9199 34479
Castelnuovo di Val di Cecina PI 19 2231 36710

Municipalities with at least 50000 inhabitants

An earthquake occurred to
34 Km NW of Grosseto (82087 inhabitants)
43 Km SW of Siena (53903 inhabitants)
77 Km SE of Livorno (159219 inhabitants)
82 Km S of Scandicci (50609 inhabitants)
84 Km SW of Firenze (382808 inhabitants)
87 Km SE of Pisa (89158 inhabitants)
89 Km SW of Arezzo (99543 inhabitants)
94 Km S of Prato (191150 inhabitants)
96 Km SE of Lucca (89046 inhabitants)
99 Km S of Pistoia (90315 inhabitants)
Recent and historical seismicity
Seismic hazard
Shakemap
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 (http://www.haisentitoilterremoto.it/) 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
Reviewed
Rev100
ML 0.4 2021-09-18
20:45:30
43.0445 10.9548 5 2021-09-18
21:07:06
Sala Sismica INGV-Roma 95601301
Preferred location and magnitude until now.
Origin information

Origin

Field Value
Time (UTC) 2021-09-18 20:45:30 ± 0.11
Latitude 43.0445 ± 0.0018
Longitude 10.9548 ± 0.0037
Depth (km) 5 ± 1 (from location)
Evaluation mode of Origin manual
Evaluation status of Origin reviewed
Version 100 -> SURVEY-INGV
Event type earthquake
Origin ID 95601301

Uncertainty

Field Value
Preferred uncertainty description uncertainty ellipse
Semi-major axis of confidence ellipse (meter) 302
Semi-minor axis of confidence ellipse (meter) 249
Azimuth of major axis of confidence ellipse. Measured clockwise from South-North direction at epicenter (gradi) 252
Circular confidence region, given by single value of horizontal uncertainty (meter) 300
Confidence level of the uncertainty (%) 68

Quality

Field Value
Largest azimuthal gap in station distribution as seen from epicenter (degree) 173
Number of associated phases, regardless of their use for origin computation 21
Number of defining phases 6
RMS of the travel time residuals of the arrivals used for the origin computation (sec) 0.07
Epicentral distance of station closest to the epicenter (degree) 0
Epicentral distance of station farthest from the epicenter (degree) 0.2617
Number of stations at which the event was observed 18
Number of stations from which data was used for origin computation 3
Magnitude information

ML:0.4

Field Value
Value 0.4
Uncertainty 0.2
Num. used stations 5
Type of magnitude ML
Reference to an origin 95601301
Agency INGV
Autore Sala Sismica INGV-Roma
Time of creation (UTC) 2021-09-18 21:07:06
Picking and Arrival
SCNL Time Uncertainty Polarity Evaluation_mode Phase Azimuth Distance Takeoff_angle Residual Weight
IV.MPNC.HHZ. 2021-09-18T20:46:56.43 3.0 negative manual Pg 14.35 0
GU.TRAV.HHZ. 2021-09-18T20:46:51.08 3.0 undecidable manual Sn 1.81 0
IV.FVI.HHZ. 2021-09-18T20:46:43.22 3.0 undecidable manual Sg 8.26 0
IV.AGLI.HHZ. 2021-09-18T20:46:39.67 3.0 undecidable manual Sn -2.69 0
RF.GEPF.HHZ. 2021-09-18T20:46:28.66 3.0 undecidable manual Sn -0.12 0
IV.MCRV.HHZ. 2021-09-18T20:46:19.63 3.0 undecidable manual Pg 9.85 0
IV.PTRP.HHZ. 2021-09-18T20:46:17.96 3.0 undecidable manual Pn -0.6 0
CR.STON.BHZ. 2021-09-18T20:46:15.68 3.0 undecidable manual Pn -1.24 0
MN.TRI.HHZ. 2021-09-18T20:46:01.41 3.0 positive manual Pg 9.51 0
IV.VAGA.HHZ. 2021-09-18T20:45:54.96 3.0 undecidable manual Pn -2.05 0
IV.CESX.HHZ. 2021-09-18T20:45:53.12 3.0 undecidable manual Sg 3.69 0
IV.SACS.HHZ. 2021-09-18T20:45:46.30 3.0 undecidable manual Sg 4.58 0
IV.CASP.HHZ. 2021-09-18T20:45:40.27 0.1 undecidable manual S 195 0.2617 99 -0.01 97
IV.OFFI.HHZ. 2021-09-18T20:45:38.10 3.0 positive manual Pn -0.25 0
IV.CASP.HHZ. 2021-09-18T20:45:35.98 0.1 undecidable manual P 195 0.2617 99 0.02 97
IV.RIBO.EHZ.01 2021-09-18T20:45:34.89 0.1 undecidable manual S 145 0.1169 110 0.04 99
IV.TRIF.CHZ. 2021-09-18T20:45:33.53 0.1 undecidable manual S 332 0.08 119 -0.03 100
IV.TRIF.CHZ. 2021-09-18T20:45:32.13 0.1 undecidable manual P 332 0.08 119 0.05 99
IV.RIBO.EHZ.01 2021-09-18T20:45:32.76 0.1 undecidable manual P 145 0.1169 110 -0.06 99
IV.OSSC.HHZ. 2021-09-18T20:45:27.02 3.0 undecidable manual P 0.1 0
IV.BRSN.HNZ. 2021-09-18T20:45:27.69 3.0 positive manual P 0.07 0
Station Magnitude and Amplitude
SCNL mag Generic_amplitude Period Type Category Unit Time_window_reference
IV.TRIF.CHN. ML:0.3 3.745E-5 0.14 AML other m 2021-09-18T20:45:33.73
IV.TRIF.CHE. ML:0.3 3.645821E-5 0.1152 AML other m 2021-09-18T20:45:34.21
IV.RIBO.EHE.01 ML:0.9 0.000108930495 0.2176 AML other m 2021-09-18T20:45:35.12
IV.CASP.HHN. ML:0.3 9.1119055E-6 0.6272 AML other m 2021-09-18T20:45:39.83
IV.CASP.HHE. ML:0.3 1.0590493E-5 0.8064 AML other m 2021-09-18T20:45:40.83
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