Istituto Nazionale di Geofisica e Vulcanologia

Earthquake with magnitude of Md 2.5 on date 11-09-1991 and time 11:46:34 (UTC) in region 4 km S Vaiano (PO)

A magnitude Md 2.5 earthquake occured in region: 4 km S Vaiano (PO), on

  • 11-09-1991 11:46:34 (UTC)
  • 11-09-1991 13:46:34 (UTC +02:00) Italian time

and geographic coordinates (lat, lon) 43.9360, 11.1110 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
Vaiano PO 4 9895 9895
Montemurlo PO 6 18456 28351
Prato PO 6 191150 219501
Montale PT 7 10737 230238
Agliana PT 9 17525 247763
Calenzano FI 9 17489 265252
Cantagallo PO 10 3105 268357
Barberino di Mugello FI 13 10836 279193
Campi Bisenzio FI 13 46166 325359
Sesto Fiorentino FI 14 48958 374317
Vernio PO 14 6060 380377
Poggio a Caiano PO 14 10007 390384
Vaglia FI 14 5073 395457
Quarrata PT 14 26190 421647
Carmignano PO 15 14450 436097
Pistoia PT 15 90315 526412
Signa FI 17 19179 545591
Scarperia e San Piero FI 17 12217 557808
Lastra a Signa FI 18 20156 577964

Municipalities with at least 50000 inhabitants

An earthquake occurred to
6 Km N of Prato (191150 inhabitants)
15 Km E of Pistoia (90315 inhabitants)
21 Km N of Scandicci (50609 inhabitants)
22 Km NW of Firenze (382808 inhabitants)
50 Km E of Lucca (89046 inhabitants)
62 Km E of Pisa (89158 inhabitants)
65 Km SW of Bologna (386663 inhabitants)
67 Km SW of Imola (69797 inhabitants)
69 Km E of Viareggio (62467 inhabitants)
71 Km N of Siena (53903 inhabitants)
73 Km SW of Faenza (58541 inhabitants)
77 Km NE of Livorno (159219 inhabitants)
78 Km E of Massa (69479 inhabitants)
80 Km S of Modena (184973 inhabitants)
81 Km W of Forlì (117913 inhabitants)
81 Km NW of Arezzo (99543 inhabitants)
83 Km E of Carrara (63133 inhabitants)
93 Km SE of Reggio nell'Emilia (171345 inhabitants)
93 Km W of Cesena (96758 inhabitants)
96 Km S of Carpi (70699 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 		Md 2.5
ML-VAX 2.2 		1991-09-11
11:46:34		 43.936 11.111 10 2013-07-15
08:41:04		 Bollettino Sismico Italiano INGV 149189
Preferred location and magnitude until now.
Origin information

Origin

Field Value
Time (UTC) 1991-09-11 11:46:34 ± 0.2
Latitude 43.9360 ± 0.0246
Longitude 11.1110 ± 0.0140
Depth (km) 10 (operator assigned)
Evaluation mode of Origin manual
Evaluation status of Origin reviewed
Version 1000 -> BULLETIN-VAX
Event type earthquake
Origin ID 149189

Uncertainty

Field Value
Preferred uncertainty description horizontal uncertainty
Semi-major axis of confidence ellipse (meter)
Semi-minor axis of confidence ellipse (meter)
Azimuth of major axis of confidence ellipse. Measured clockwise from South-North direction at epicenter (gradi)
Circular confidence region, given by single value of horizontal uncertainty (meter) 2956.4
Confidence level of the uncertainty (%) 68

Quality

Field Value
Largest azimuthal gap in station distribution as seen from epicenter (degree) 141
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) 0.5
Epicentral distance of station closest to the epicenter (degree) 0.00348
Epicentral distance of station farthest from the epicenter (degree) 0.01255
Number of stations at which the event was observed 7
Number of stations from which data was used for origin computation 7
Magnitudes information

Md:2.5

Field Value
Value 2.5
Uncertainty
Num. used stations 3
Type of magnitude Md
Reference to an origin 149189
Agency INGV
Autore Bollettino Sismico Italiano INGV
Time of creation (UTC) 2013-01-04 19:19:15

ML:2.2

Field Value
Value 2.2
Uncertainty
Num. used stations 3
Type of magnitude ML
Reference to an origin 149189
Agency INGV
Autore Bollettino Sismico Italiano INGV
Time of creation (UTC) 2015-04-28 13:07:13
Picking and Arrival
SCNL Time Uncertainty Polarity Evaluation_mode Phase Azimuth Distance(km) Takeoff_angle Residual Weight
--.ARV.Z. 1991-09-11T11:47:18.00 10.0 undecidable manual SN 107 1.3875 0.04 0.5
--.ARV.Z. 1991-09-11T11:47:00.50 10.0 undecidable manual PN 107 1.3875 0.98 0.5
--.CRE.Z. 1991-09-11T11:46:57.95 10.0 undecidable manual SG 116 0.6882 -0.24 0.8
--.SFI.Z. 1991-09-11T11:46:53.43 10.0 undecidable manual SG 92 0.5328 0.13 0.9
--.PGD.Z. 1991-09-11T11:46:52.40 10.0 undecidable manual SG 97 0.444 1.55 0.1
--.PII.Z. 1991-09-11T11:46:51.78 10.0 undecidable manual SG 242 0.4662 0.3 0.8
--.BDI.Z. 1991-09-11T11:46:47.95 10.0 undecidable manual SG 288 0.3885 -0.82 0.5
--.MME.Z. 1991-09-11T11:46:47.85 10.0 undecidable manual SG 310 0.3885 -0.96 0.4
--.CRE.Z. 1991-09-11T11:46:46.84 10.0 undecidable manual PG 116 0.6882 -1.27 0.5
--.PII.Z. 1991-09-11T11:46:44.44 10.0 undecidable manual PG 242 0.4662 0.21 2.1
--.SFI.Z. 1991-09-11T11:46:44.65 10.0 undecidable manual PG 92 0.5328 -0.64 1.5
--.PGD.Z. 1991-09-11T11:46:43.62 10.0 undecidable manual PG 97 0.444 -0.04 2.2
--.MME.Z. 1991-09-11T11:46:43.42 10.0 undecidable manual PG 310 0.3885 0.73 1.3
--.BDI.Z. 1991-09-11T11:46:42.70 10.0 undecidable manual PG 288 0.3885 0.03 2.2
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