Earthquake with magnitude of M 2.0 on date 23-10-1985 and time 17:35:35 (UTC) in region Costa Ligure Occidentale (Imperia)

A magnitude M 2.0 earthquake occured in region: Costa Ligure Occidentale (Imperia), on

  • 23-10-1985 17:35:35 (UTC)
  • 23-10-1985 18:35:35 (UTC +01:00) Italian time

and geographic coordinates (lat, lon) 43.7670, 7.8650 at 17 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.

Municipalities within 20 km from the epicenter

Distances are determinated based on the geographic coordintes of the (Istat).
Municipality Region Dist Inh Cum Inh
Riva Ligure IM 8 2910 2910
Santo Stefano al Mare IM 8 2197 5107
Taggia IM 9 14116 19223
Sanremo IM 9 54807 74030
Pompeiana IM 10 823 74853
Terzorio IM 10 216 75069
Castellaro IM 11 1256 76325
Cipressa IM 11 1290 77615
Costarainera IM 12 828 78443
Ospedaletti IM 12 3367 81810
San Lorenzo al Mare IM 13 1297 83107
Pietrabruna IM 14 501 83608
Civezza IM 14 609 84217
Ceriana IM 15 1250 85467
Seborga IM 15 315 85782
Bordighera IM 16 10469 96251
Vallebona IM 17 1310 97561
Badalucco IM 17 1136 98697
Dolcedo IM 17 1415 100112
Vallecrosia IM 18 6956 107068
Montalto Ligure IM 18 377 107445
Soldano IM 18 977 108422
San Biagio della Cima IM 18 1329 109751
Imperia IM 19 42034 151785
Prelà IM 19 503 152288
Perinaldo IM 19 870 153158
Bajardo IM 19 312 153470
Camporosso IM 20 5632 159102
Vasia IM 20 389 159491

Municipalities with at least 50000 inhabitants

An earthquake occurred to
9 Km SE of Sanremo (54807 inhabitants)
74 Km SE of Cuneo (56081 inhabitants)
78 Km SW of Savona (61345 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
M 2.0 1985-10-23
17:35:35
43.767 7.865 17 2013-07-15
08:40:51
Bollettino Sismico Italiano INGV 14989
Preferred location and magnitude until now.
Origin information

Origin

Field Value
Time (UTC) 1985-10-23 17:35:35 ± 0.848
Latitude 43.7670 ± 0.0374
Longitude 7.8650 ± 0.0716
Depth (km) 17 ± 5 (from location)
Evaluation mode of Origin manual
Evaluation status of Origin reviewed
Version 1000 -> BULLETIN-VAX
Event type earthquake
Origin ID 14989

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) 7100.7
Confidence level of the uncertainty (%) 68

Quality

Field Value
Largest azimuthal gap in station distribution as seen from epicenter (degree) 331
Number of associated phases, regardless of their use for origin computation 6
Number of defining phases 6
RMS of the travel time residuals of the arrivals used for the origin computation (sec) 0.4
Epicentral distance of station closest to the epicenter (degree) 0.00130
Epicentral distance of station farthest from the epicenter (degree) 0.00478
Number of stations at which the event was observed 3
Number of stations from which data was used for origin computation 3
Magnitude information

M:2.0

Field Value
Value 2.0
Uncertainty
Num. used stations
Type of magnitude M
Reference to an origin 14989
Agency INGV
Autore Bollettino Sismico Italiano INGV
Time of creation (UTC) 2015-04-28 09:48:29
Picking and Arrival
SCNL Time Uncertainty Polarity Evaluation_mode Phase Azimuth Distance Takeoff_angle Residual Weight
--.ROB.Z. 1985-10-23T17:35:54.30 10.0 undecidable manual SG 0 0.0048 0 0.8
--.FIN.Z. 1985-10-23T17:35:52.60 10.0 undecidable manual SG 29 0.0045 -0.77 0.3
--.ROB.Z. 1985-10-23T17:35:46.20 10.0 undecidable manual PG 0 0.0048 0.02 2.1
--.FIN.Z. 1985-10-23T17:35:46.20 10.0 undecidable manual PG 29 0.0045 0.55 1.2
--.IMP.Z. 1985-10-23T17:35:43.40 10.0 undecidable manual SG 7 0.0013 0.68 0.4
--.IMP.Z. 1985-10-23T17:35:38.90 10.0 undecidable manual PG 7 0.0013 -0.59 1.2
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, http://terremoti.ingv.it/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