Earthquake with magnitude of mb 5.1 on date 01-04-2021 and time 16:33:39 (Italy) in region Northern Algeria [Land: Algeria]

A magnitude mb 5.1 earthquake occured in region: Northern Algeria [Land: Algeria], on

  • 01-04-2021 14:33:39 (UTC)
  • 01-04-2021 16:33:39 (UTC +02:00) Italian time

and geographic coordinates (lat, lon) 36.768, 7.148 at 20 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

No Italian municipalities within 20 km distance.

Municipalities with at least 50000 inhabitants

No Italian municipalities within 100 km from the epicenter with at least 50000 inhabitants.

Recent and historical seismicity
Seismic hazard

These three maps show the results of the analysis using the software ShakeMap designed to provide the level of ground shaking experienced in a region using the data recorded by seismometers and strong motion instruments and seismological information regarding the attenuation of the wavefield with distance and the site characteristics. The Shakemaps are determined for research purposes to provide fast estimates of the level of ground shaking produced by the earthquake. The maps are calculated automatically and adjourned progressively as more data become available. See for additional information.

The red star indicates the epicenter. The red triangles show the stations of the INGV Italian National Seismic Network and the blue triangles those of the Nationa Accelerometric Network of the Dipartimento della Protezione Civile.

Intensity Shakemap

Intensity Shakemap

This map shows the distribution of the istrumentally derived intensities. To this purpose, it is used a conversion relation between ground acceleration and velocity, and the Mercalli Modificata (MMI - Modified Mercalli Intensity) scale. In general, the Mercalli intensity scale relies on the effects that the ground shaking produces as reported by an observer.
Peak ground acceleration Shakemap

Peak ground acceleration Shakemap

This map shows This map shows the distribution of peak ground acceleration expressed as per cent of the acceleration of gravity (i.e., g = 9.81 m/s²).
Peak velocity Shakemap

Peak velocity Shakemap

This map shows the distribution of peak ground velocities expressed in cm/s.
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 ( 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
mb 5.1 2021-04-01
36.7682 7.1477 20 2021-04-01
Sala Sismica INGV-Roma 88681271
Preferred location and magnitude until now.
Origin information


Field Value
Time (UTC) 2021-04-01 14:33:39
Latitude 36.7682
Longitude 7.1477
Depth (km) 20 (from location)
Evaluation mode of Origin automatic
Evaluation status of Origin reviewed
Version 100 -> SURVEY-INGV-A
Event type earthquake
Origin ID 88681271


Field Value
Preferred uncertainty description uncertainty ellipse
Semi-major axis of confidence ellipse (meter) 5818
Semi-minor axis of confidence ellipse (meter) 1638
Azimuth of major axis of confidence ellipse. Measured clockwise from South-North direction at epicenter (gradi) 330
Circular confidence region, given by single value of horizontal uncertainty (meter) 4812.1
Confidence level of the uncertainty (%) 68


Field Value
Largest azimuthal gap in station distribution as seen from epicenter (degree) 202.815
Number of associated phases, regardless of their use for origin computation 24
Number of defining phases 24
RMS of the travel time residuals of the arrivals used for the origin computation (sec) 1.38861
Epicentral distance of station closest to the epicenter (degree) 3.24284
Epicentral distance of station farthest from the epicenter (degree) 68.66207
Number of stations at which the event was observed 22
Number of stations from which data was used for origin computation 22
Magnitude information


Field Value
Value 5.1
Uncertainty 0.2
Num. used stations 12
Type of magnitude mb
Reference to an origin 88681271
Agency INGV
Autore early-est_ee1.1.9
Time of creation (UTC) 2021-04-01 14:56:16
Picking and Arrival
SCNL Time Uncertainty Polarity Evaluation_mode Phase Azimuth Distance Takeoff_angle Residual Weight
US.EYMN.BHZ.00 2021-04-01T14:44:39.83 10.0 positive automatic P 315 68.6621 -1.02121 0.270889
IU.MAKZ.BHZ.00 2021-04-01T14:43:04.95 10.0 positive automatic P 54 54.5551 -0.729084 0.481391
G.SSB.BHZ.00 2021-04-01T14:35:43.05 10.0 positive automatic P 348 8.7332 -1.08233 0.952381
II.ARTI.BHZ.00 2021-04-01T14:41:02.92 10.0 negative automatic P 43 39.09 -1.76652 0.71381
IU.KIEV.BHZ.00 2021-04-01T14:38:22.22 10.0 negative automatic P 42 21.0312 0.844395 0.930233
CZ.KHC.BHZ. 2021-04-01T14:36:47.25 10.0 positive automatic P 19 13.2157 1.76608 0.952381
LX.MESJ.BHZ. 2021-04-01T14:36:32.16 10.0 positive automatic P 280 12.2563 -0.13379 0.952381
GE.MTE.BHZ. 2021-04-01T14:36:31.60 10.0 negative automatic P 292 12.0275 2.32884 0.930233
HT.AGG.HHZ. 2021-04-01T14:36:31.66 10.0 negative automatic P 75 12.1799 0.347266 0.934579
PM.PVAQ.BHZ. 2021-04-01T14:36:26.16 10.0 positive automatic P 278 11.8625 -0.744846 0.930233
G.ECH.BHZ.00 2021-04-01T14:36:19.90 10.0 positive automatic P 0 11.4477 -1.39168 0.952381
RD.MFF.BHZ. 2021-04-01T14:36:17.84 10.0 negative automatic P 333 11.2295 -0.41886 0.934579
RD.PGF.BHZ. 2021-04-01T14:36:16.34 10.0 positive automatic S 13 5.9526 2.86863 0
RD.LOR.BHZ. 2021-04-01T14:36:12.32 10.0 positive automatic P 348 10.7775 0.210185 0.952381
IU.PAB.BHZ.00 2021-04-01T14:35:55.17 10.0 positive automatic P 291 9.4492 1.17406 0.952381
MN.BNI.BHZ. 2021-04-01T14:35:38.92 10.0 negative automatic P 358 8.291 0.734936 0.952381
IV.BOB.BHZ. 2021-04-01T14:35:38.15 10.0 positive automatic P 12 8.1859 1.48489 0.952381
RD.MTLF.BHZ. 2021-04-01T14:35:27.44 10.0 positive automatic P 332 7.5754 -0.752507 0.970874
IV.MGAB.BHZ. 2021-04-01T14:35:25.30 10.0 negative automatic P 30 7.2273 1.85118 0.97561
WM.CART.BHZ. 2021-04-01T14:35:13.02 10.0 positive automatic P 280 6.5418 -0.92947 0.97561
RD.PGF.BHZ. 2021-04-01T14:35:05.66 10.0 positive automatic P 13 5.9526 -0.381011 0.961538
WM.MAHO.BHZ. 2021-04-01T14:34:36.70 10.0 negative automatic P 325 3.8582 -0.363427 0.952381
MN.VSL.BHZ. 2021-04-01T14:34:25.92 10.0 positive automatic P 32 3.2428 -2.74903 0.869565
TDMT - Time Domain Moment Tensor
Fault Plane solutions in the area
Type Description Link
QuakeML - small Event, Origin, FocalMechanism Download
QuakeML - full Event, Origin, FocalMechanism, Amplitude, Arrival, Pick, Station Magnitude Download