Istituto Nazionale di Geofisica e Vulcanologia

Earthquake with magnitude of Md 3.1 on date 23-10-1991 and time 21:44:10 (UTC) in region 9 km NW Milo (CT)

A magnitude Md 3.1 earthquake occured in region: 9 km NW Milo (CT), on

  • 23-10-1991 21:44:10 (UTC)
  • 23-10-1991 22:44:10 (UTC +01:00) Italian time

and geographic coordinates (lat, lon) 37.7650, 15.0250 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
Milo CT 9 1087 1087
Zafferana Etnea CT 10 9517 10604
Sant'Alfio CT 11 1582 12186
Santa Venerina CT 13 8592 20778
Linguaglossa CT 14 5403 26181
Randazzo CT 14 10900 37081
Piedimonte Etneo CT 14 3963 41044
Giarre CT 15 27659 68703
Mascali CT 15 14282 82985
Moio Alcantara ME 15 717 83702
Maletto CT 16 3920 87622
Castiglione di Sicilia CT 16 3215 90837
Riposto CT 16 14838 105675
Fiumefreddo di Sicilia CT 17 9623 115298
Pedara CT 17 14102 129400
Nicolosi CT 17 7463 136863
Ragalna CT 17 3924 140787
Bronte CT 17 19172 159959
Trecastagni CT 17 10910 170869
Malvagna ME 17 733 171602
Santa Domenica Vittoria ME 18 980 172582
Viagrande CT 18 8563 181145
Francavilla di Sicilia ME 18 3945 185090
Roccella Valdemone ME 19 666 185756
Calatabiano CT 19 5308 191064
Biancavilla CT 19 24007 215071
Motta Camastra ME 20 845 215916
Belpasso CT 20 28108 244024
Aci Sant'Antonio CT 20 17984 262008
Aci Bonaccorsi CT 20 3524 265532

Municipalities with at least 50000 inhabitants

An earthquake occurred to
21 Km NW of Acireale (52622 inhabitants)
30 Km N of Catania (314555 inhabitants)
67 Km SW of Reggio di Calabria (183035 inhabitants)
67 Km SW of Messina (238439 inhabitants)
82 Km N of Siracusa (122291 inhabitants)
90 Km E of Caltanissetta (63360 inhabitants)
97 Km N of Ragusa (73313 inhabitants)
100 Km NE of Vittoria (63339 inhabitants)
Recent and historical seismicity

These maps show the seismic activity in different time intervals, before the seismic event to which they refer. Data reported in the first two maps come from the analysis carried out in real time by the personnel of the INGV Operating Rooms, immediately after each earthquake. The third map shows data from 1985 to the date of the earthquake: the locations are reviewed by the seismological analysts of the INGV Italian Seismic Bulletin (Bollettino Sismico Italiano dell’INGV). The localization parameters (hypocentral coordinates and magnitude) are the best possible estimate with the data available to the INGV, but are constantly updated according to further data that become available. The location and magnitude parameters, subsequently reviewed by seismological analysts, may vary.

Earthquakes of the 3 days preceding this event

Earthquakes of the 3 days preceding this event

This map shows the earthquake epicenters with magnitude ≥ 0.0, localized with data recorded by the National Seismic Network and other collaborative networks both in Italy and in neighboring countries, in the 72 hours preceding this event. The size of the circle indicates the different classes of magnitude. The colors indicate the different time intervals preceding the seismic event. The black and white star is the epicenter of the current earthquake.
Earthquakes of the 90 days preceding this event

Earthquakes of the 90 days preceding this event

This map shows the earthquake epicenters with magnitude ≥ 2.0, localized with data recorded by the National Seismic Network and other collaborative networks both in Italy and in neighboring countries, in the 90 days preceding this event. The size of the circle indicates the different classes of magnitude. The colors indicate the different time intervals preceding the seismic event. The black and white star is the epicenter of the current earthquake.
Earthquakes from 1985 to the date of the event

Earthquakes from 1985 to the date of the event

This map shows the earthquake epicenters with magnitude ≥ 3.0, localized with data recorded by the National Seismic Network and other collaborative networks both in Italy and in neighboring countries, from 1985 to the date of this event. The size of the circle indicates the different classes of magnitude. The colors indicate the different time intervals preceding the seismic event. The black and white star is the epicenter of the current earthquake.
Earthquakes since 1000 AD until 2019

Earthquakes since 1000 AD until 2019

This map shows the epicenters of the historical earthquakes catalogue CPT15 (Catalogo Parametrico dei Terremoti Italiani, 2015 version 3.0, https://doi.org/10.13127/cpti/cpti15.3) since 1000 AD until 2019. The size of the square indicates the different classes of magnitude. For earthquakes with magnitude ≥ 6.0, it is also shown the year of occurrence and the magnitude value. The black and white star is the epicenter of the current earthquake.
Seismic hazard

Seismic hazard maps provide probabilistic estimates of the earthquake ground shaking exceeding a given threshold in a given geographic region within a given time window. Thus, it is not a deterministic prediction - a target that may be never reached given the complexity of the earthquake physical phenomenon - nor of the maximum expected earthquake since this has extremely low probabilities to occur.

In 2004, it was published the seismic hazard map of Italy (http://zonesismiche.mi.ingv.it) that provides a picture of the most hazardous geographic regions. The seismic hazard map of Italy (GdL MPS, 2004; rif. Ordinanza PCM del 28 aprile 2006, n. 3519, All. 1b) provides the 10% probability of exceedance in 50 years of the horizontal acceleration at rock sites (i.e., Vs30>800 m/s; cat. A, 3.2.1 of the D.M. 14.09.2005).

The colours indicate the various values of the ground acceleration that have 10% to be exceeded within 50 years. In general, the colours associated to low values of acceleration refer to areas that are less hazardous and stronger earthquakes repeat less frequently although they may still occur.

Seismic hazard map

Seismic hazard map

This map shows the seismic hazard map of Italy for the region where the earthquake occurred.
Shakemap
Felt maps
Locations history
Type Magnitude Date and Time (UTC) Latitude Longitude Depth (km) Published time (UTC) Author Location ID
Bulletin
Rev1000 		Md 3.1 1991-10-23
21:44:10		 37.765 15.025 10 2013-07-15
08:40:51		 Bollettino Sismico Italiano INGV 151599
Preferred location and magnitude until now.
Origin information

Origin

Field Value
Time (UTC) 1991-10-23 21:44:10 ± 0.55
Latitude 37.7650 ± 0.0097
Longitude 15.0250 ± 0.0185
Depth (km) 10 ± 4 (from location)
Evaluation mode of Origin manual
Evaluation status of Origin reviewed
Version 1000 -> BULLETIN-VAX
Event type earthquake
Origin ID 151599

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) 1950.1
Confidence level of the uncertainty (%) 68

Quality

Field Value
Largest azimuthal gap in station distribution as seen from epicenter (degree) 109
Number of associated phases, regardless of their use for origin computation 31
Number of defining phases 31
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) 0.00186
Epicentral distance of station farthest from the epicenter (degree) 0.03157
Number of stations at which the event was observed 16
Number of stations from which data was used for origin computation 16
Magnitude information

Md:3.1

Field Value
Value 3.1
Uncertainty
Num. used stations 6
Type of magnitude Md
Reference to an origin 151599
Agency INGV
Autore Bollettino Sismico Italiano INGV
Time of creation (UTC) 2013-01-04 19:21:30
Picking and Arrival
SCNL Time Uncertainty Polarity Evaluation_mode Phase Azimuth Distance(km) Takeoff_angle Residual Weight
--.BRT.Z. 1991-10-23T21:45:45.00 10.0 undecidable manual SN 27 3.5076 0.73 0.2
--.MGR.Z. 1991-10-23T21:45:16.68 10.0 undecidable manual SN 9 2.3976 -1.27 0.1
--.CSI.Z. 1991-10-23T21:45:15.50 10.0 undecidable manual SN 25 2.2422 1.34 0.1
--.MMN.Z. 1991-10-23T21:45:15.60 10.0 undecidable manual SN 19 2.2422 1.31 0.1
--.ROI.Z. 1991-10-23T21:45:14.40 10.0 undecidable manual SN 33 2.1645 2.09 0
--.BRT.Z. 1991-10-23T21:45:04.15 10.0 undecidable manual PN 27 3.5076 -0.34 0.9
--.CZI.Z. 1991-10-23T21:45:03.20 10.0 undecidable manual SN! 30 1.6872 2.26 0
--.GRI.Z. 1991-10-23T21:44:56.50 10.0 undecidable manual SN 45 1.5207 -0.39 0.6
--.SGO.Z. 1991-10-23T21:44:55.50 10.0 undecidable manual PN 4 2.7972 0.79 0.6
--.MGR.Z. 1991-10-23T21:44:48.39 10.0 undecidable manual PN 9 2.3976 -0.9 0.6
--.MMN.Z. 1991-10-23T21:44:47.80 10.0 undecidable manual PN 19 2.2422 0.62 0.9
--.CSI.Z. 1991-10-23T21:44:46.82 10.0 undecidable manual PN 25 2.2422 -0.28 1.2
--.ROI.Z. 1991-10-23T21:44:45.98 10.0 undecidable manual PN 33 2.1645 -0.06 1.4
--.SOI.Z. 1991-10-23T21:44:39.00 10.0 undecidable manual SG 68 0.8658 -1 0.3
--.CZI.Z. 1991-10-23T21:44:38.26 10.0 undecidable manual PN 30 1.6872 -1.22 0.7
--.GRI.Z. 1991-10-23T21:44:37.00 10.0 undecidable manual PN 45 1.5207 -0.13 1.6
--.PZI.Z. 1991-10-23T21:44:35.00 10.0 undecidable manual SG 185 0.7104 0.02 0.7
--.MEU.Z. 1991-10-23T21:44:33.00 10.0 undecidable manual SG 193 0.666 -0.69 0.7
--.MO9.Z. 1991-10-23T21:44:31.00 10.0 undecidable manual SG 65 0.5772 0.31 0.6
--.ATN.Z. 1991-10-23T21:44:30.00 10.0 undecidable manual SG 41 0.5217 1.09 0.2
--.AU9.Z. 1991-10-23T21:44:29.50 10.0 undecidable manual SG 163 0.5328 0.23 0.7
--.SOI.Z. 1991-10-23T21:44:27.00 10.0 positive manual PG 68 0.8658 -0.38 3
--.PZI.Z. 1991-10-23T21:44:24.50 10.0 undecidable manual PG 185 0.7104 0.02 1.8
--.MEU.Z. 1991-10-23T21:44:23.00 10.0 undecidable manual PG 193 0.666 -0.73 1
--.MNO.Z. 1991-10-23T21:44:22.50 10.0 undecidable manual SG 302 0.3108 0.42 0.6
--.MO9.Z. 1991-10-23T21:44:22.00 10.0 undecidable manual PG 65 0.5772 -0.01 1.8
--.ATN.Z. 1991-10-23T21:44:21.00 10.0 negative manual PG 41 0.5217 0.02 3.5
--.AU9.Z. 1991-10-23T21:44:21.20 10.0 positive manual PG 163 0.5328 0.02 3.5
--.GIO.Z. 1991-10-23T21:44:19.50 10.0 undecidable manual SG 161 0.2109 0.66 0.5
--.MNO.Z. 1991-10-23T21:44:17.00 10.0 undecidable manual PG 302 0.3108 -0.03 1.8
--.GIO.Z. 1991-10-23T21:44:16.50 10.0 undecidable manual PG 161 0.2109 1.34 0.3
TDMT - Time Domain Moment Tensor
Fault Plane solutions in the area
Fault Plane solutions

Fault Plane solutions

The map reports the fault plane solutions for earthquakes in the region from 1977 to the date of this event. Red moment tensors are determined using the Regional Centroid Moment Tensor technique (RCMT, http://www.bo.ingv.it/RCMT) applied for earthquakes with magnitude larger than 4.5 in the Euro-Mediterranenan area. Occasionally, when a station azimuthal coverage exists RCMTs can be obtained also for earthquakes with magnitude down to 4.0. The gray moment tensors are obtained with the Time Domain Moment Tensor method (TDMT, /tdmt). This technique is applied to earthquakes with magnitude ML greater than 3.2, when it is possible. The size of symbols scales with the calculated moment magnitude Mw.
Download
Type Description Link
QuakeML - small Event, Origin, FocalMechanism Download
QuakeML - full Event, Origin, FocalMechanism, Amplitude, Arrival, Pick, Station Magnitude Download