Istituto Nazionale di Geofisica e Vulcanologia

Earthquake with magnitude of ML 0.4 on date 20-04-2011 and time 22:49:51 (Italy) in region 4 km N Posta (RI)

A magnitude ML 0.4 earthquake occured in region: 4 km N Posta (RI), on

  • 20-04-2011 20:49:51 (UTC)
  • 20-04-2011 22:49:51 (UTC +02:00) Italian time

and geographic coordinates (lat, lon) 42.5580, 13.0990 at 7 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
Posta RI 4 694 694
Borbona RI 6 617 1311
Cittareale RI 8 482 1793
Leonessa RI 11 2435 4228
Micigliano RI 12 127 4355
Montereale AQ 13 2581 6936
Cagnano Amiterno AQ 15 1369 8305
Antrodoco RI 16 2588 10893
Monteleone di Spoleto PG 16 599 11492
Capitignano AQ 17 665 12157
Borgo Velino RI 17 972 13129
Amatrice RI 18 2657 15786
Poggio Bustone RI 18 2055 17841
Cantalice RI 19 2755 20596
Castel Sant'Angelo RI 19 1308 21904
Barete AQ 19 737 22641
Cascia PG 19 3217 25858
Accumoli RI 20 667 26525

Municipalities with at least 50000 inhabitants

An earthquake occurred to
34 Km NW of L'Aquila (69753 inhabitants)
37 Km E of Terni (111501 inhabitants)
51 Km W of Teramo (54892 inhabitants)
55 Km SE of Foligno (57155 inhabitants)
69 Km NE of Guidonia Montecelio (88673 inhabitants)
71 Km NE of Tivoli (56533 inhabitants)
83 Km E of Viterbo (67173 inhabitants)
84 Km SE of Perugia (166134 inhabitants)
86 Km W of Montesilvano (53738 inhabitants)
90 Km NE of Roma (2864731 inhabitants)
91 Km W of Chieti (51815 inhabitants)
92 Km W of Pescara (121014 inhabitants)
100 Km N of Velletri (53303 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 1.7
ML 0.4 		2011-04-20
20:49:51		 42.558 13.099 7 2014-10-21
12:27:13		 Bollettino Sismico Italiano INGV 1199199
Preferred location and magnitude until now.
Origin information

Origin

Field Value
Time (UTC) 2011-04-20 20:49:51 ± 0.13
Latitude 42.5580 ± 0.0045
Longitude 13.0990 ± 0.0037
Depth (km) 7 ± 1 (from location)
Evaluation mode of Origin manual
Evaluation status of Origin reviewed
Version 1000 -> BULLETIN-SISPICK
Event type earthquake
Origin ID 1199199

Uncertainty

Field Value
Preferred uncertainty description uncertainty ellipse
Semi-major axis of confidence ellipse (meter) 467
Semi-minor axis of confidence ellipse (meter) 149
Azimuth of major axis of confidence ellipse. Measured clockwise from South-North direction at epicenter (gradi) 21
Circular confidence region, given by single value of horizontal uncertainty (meter) 583.1
Confidence level of the uncertainty (%) 68

Quality

Field Value
Largest azimuthal gap in station distribution as seen from epicenter (degree) 196
Number of associated phases, regardless of their use for origin computation 11
Number of defining phases 10
RMS of the travel time residuals of the arrivals used for the origin computation (sec) 0.13
Epicentral distance of station closest to the epicenter (degree) 0.00000
Epicentral distance of station farthest from the epicenter (degree) 0.18796
Number of stations at which the event was observed 6
Number of stations from which data was used for origin computation 5
Magnitudes information

ML:0.4

Field Value
Value 0.4
Uncertainty 0.2
Num. used stations
Type of magnitude ML
Reference to an origin 1199199
Agency INGV
Autore Bollettino Sismico Italiano INGV
Time of creation (UTC) 2013-01-05 23:27:33

Md:1.7

Field Value
Value 1.7
Uncertainty 0.1
Num. used stations
Type of magnitude Md
Reference to an origin 1199199
Agency INGV
Autore Bollettino Sismico Italiano INGV
Time of creation (UTC) 2013-01-05 23:27:33
Picking and Arrival
SCNL Time Uncertainty Polarity Evaluation_mode Phase Azimuth Distance(km) Takeoff_angle Residual Weight
IV.NRCA.HHE. 2011-04-20T20:50:00.10 10.0 undecidable manual Pg 0 0 0
IV.SMA1.EHZ. 2011-04-20T20:49:59.45 0.3 undecidable manual Sg 67 20.868 0.115 72
IV.RM32.EHN. 2011-04-20T20:49:57.47 0.3 undecidable manual Sg 85 15.873 -0.257 70
IV.SMA1.EHZ. 2011-04-20T20:49:56.11 0.3 undecidable manual Pg 67 20.868 -0.002 73
IV.RM33.EHZ. 2011-04-20T20:49:56.18 0.1 undecidable manual Sg 120 10.878 -0.008 99
IV.LNSS.HHN. 2011-04-20T20:49:55.07 0.3 undecidable manual Sg 316 6.8931 -0.033 75
IV.RM32.EHN. 2011-04-20T20:49:55.15 0.3 undecidable manual Pg 85 15.873 -0.032 74
IV.RM29.EHZ. 2011-04-20T20:49:55.56 0.1 undecidable manual Sg 88 8.3805 0.07 99
IV.RM33.EHZ. 2011-04-20T20:49:54.31 0.1 undecidable manual Pg 120 10.878 0.02 99
IV.LNSS.HHN. 2011-04-20T20:49:53.66 0.1 undecidable manual Pg 316 6.8931 -0.01 100
IV.RM29.EHZ. 2011-04-20T20:49:53.98 0.1 undecidable manual Pg 88 8.3805 0.086 98
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