Earthquake with magnitude of Mwp 6.4 on date 25-04-2021 and time 22:28:00 (UTC) in region Tonga [Sea]

A magnitude Mwp 6.4 earthquake occured in region: Tonga [Sea], on

  • 25-04-2021 22:28:00 (UTC)
  • 26-04-2021 00:28:00 (UTC +02:00) Italian time
  • 26-04-2021 11:28:00 (UTC +13:00) local time in the region of the earthquake (Pacific/Tongatapu)

and geographic coordinates (lat, lon) -21.649, -176.996 at 232 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
Shakemap

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 http://shakemap.rm.ingv.it/ 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 (http://www.haisentitoilterremoto.it/) 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
Reviewed
Rev100
mb 5.6
Mwp 6.4

Mwpd 6.4
2021-04-25
22:28:00
-21.6492 -176.996 232 2021-04-25
22:42:11
Sala Sismica INGV-Roma 89475971
Preferred location and magnitude until now.
Origin information

Origin

Field Value
Time (UTC) 2021-04-25 22:28:00
Latitude -21.6492
Longitude -176.9960
Depth (km) 232 (from location)
Evaluation mode of Origin automatic
Evaluation status of Origin reviewed
Version 100 -> SURVEY-INGV-A
Event type earthquake
Origin ID 89475971

Uncertainty

Field Value
Preferred uncertainty description uncertainty ellipse
Semi-major axis of confidence ellipse (meter) 12455
Semi-minor axis of confidence ellipse (meter) 2527
Azimuth of major axis of confidence ellipse. Measured clockwise from South-North direction at epicenter (gradi) 114
Circular confidence region, given by single value of horizontal uncertainty (meter) 10059.3
Confidence level of the uncertainty (%) 68

Quality

Field Value
Largest azimuthal gap in station distribution as seen from epicenter (degree) 64.8707
Number of associated phases, regardless of their use for origin computation 95
Number of defining phases 95
RMS of the travel time residuals of the arrivals used for the origin computation (sec) 1.52047
Epicentral distance of station closest to the epicenter (degree) 6.07896
Epicentral distance of station farthest from the epicenter (degree) 79.88388
Number of stations at which the event was observed 76
Number of stations from which data was used for origin computation 76
Magnitudes information

Mwp:6.4

Field Value
Value 6.4
Uncertainty 0.3
Num. used stations 40
Type of magnitude Mwp
Reference to an origin 89475971
Agency INGV
Autore early-est_ee1.1.9
Time of creation (UTC) 2021-04-25 22:42:11

Mwpd:6.4

Field Value
Value 6.4
Uncertainty 0.2
Num. used stations 35
Type of magnitude Mwpd
Reference to an origin 89475971
Agency INGV
Autore early-est_ee1.1.9
Time of creation (UTC) 2021-04-25 22:42:11

mb:5.6

Field Value
Value 5.6
Uncertainty 0.2
Num. used stations 53
Type of magnitude mb
Reference to an origin 89475971
Agency INGV
Autore early-est_ee1.1.9
Time of creation (UTC) 2021-04-25 22:42:11
Picking and Arrival
SCNL Time Uncertainty Polarity Evaluation_mode Phase Azimuth Distance Takeoff_angle Residual Weight
BK.CMB.BHZ.00 2021-04-25T22:39:43.02 10.0 positive automatic P 42 79.8839 0.385807 0.171978
IU.PMSA.BHZ.00 2021-04-25T22:39:43.42 10.0 positive automatic P 156 79.6676 2.05575 0.16623
IU.INCN.BHZ.00 2021-04-25T22:39:39.47 10.0 negative automatic P 318 79.3973 -0.444484 0.172446
GE.MNAI.BHZ. 2021-04-25T22:39:37.92 10.0 negative automatic P 270 79.1476 -0.663489 0.163561
ND.KOUNC.BHZ.00 2021-04-25T22:39:30.75 10.0 negative automatic ScP 270 17.4857 3.11342 0
IU.YSS.BHZ.00 2021-04-25T22:39:29.45 10.0 negative automatic P 333 77.6047 -0.703157 0
IU.PET.BHZ.00 2021-04-25T22:39:27.52 10.0 negative automatic P 345 77.6052 -2.62913 0.193443
AU.NFK.BHZ.00 2021-04-25T22:39:26.94 10.0 negative automatic ScP 238 15.4718 3.2646 0
ND.ONTNC.BHZ.00 2021-04-25T22:39:26.95 10.0 negative automatic ScP 264 15.3526 3.52445 0
AT.AKUT.BHZ. 2021-04-25T22:39:20.74 10.0 positive automatic P 7 76.3958 -2.66171 0.212257
IU.TATO.BHZ.00 2021-04-25T22:39:18.67 10.0 positive automatic P 305 75.7444 -1.09316 0.211907
AU.XMI.BHZ. 2021-04-25T22:39:12.00 10.0 negative automatic P 265 74.4735 0.45871 0.235976
JP.YOJ.BHZ. 2021-04-25T22:39:10.80 10.0 negative automatic P 305 74.3147 -0.784803 0.21659
II.ERM.BHZ.00 2021-04-25T22:39:06.67 10.0 negative automatic P 330 73.542 -0.444609 0
MY.SBM.BHZ. 2021-04-25T22:39:05.37 10.0 negative automatic P 280 73.1533 0.480078 0.233587
IU.ADK.BHZ.00 2021-04-25T22:39:04.42 10.0 positive automatic P 0 73.5288 -2.63372 0.240584
IU.MAJO.BHZ.00 2021-04-25T22:38:56.17 10.0 negative automatic P 323 71.9274 -1.53062 0.258424
JP.JOW.BHZ. 2021-04-25T22:38:56.75 10.0 negative automatic P 310 71.7966 -0.142076 0.259909
G.INU.BHZ.00 2021-04-25T22:38:55.11 10.0 negative automatic P 322 71.7317 -1.38289 0.237982
GE.SMRI.BHZ. 2021-04-25T22:38:54.02 10.0 negative automatic P 270 71.2317 0.500365 0.266374
MY.KKM.BHZ. 2021-04-25T22:38:52.52 10.0 negative automatic P 285 71.0049 0.251011 0
MY.LDM.BHZ. 2021-04-25T22:38:39.12 10.0 negative automatic P 285 68.5811 1.70795 0.28423
IU.QSPA.BHZ.00 2021-04-25T22:38:37.47 10.0 negative automatic P 180 68.2922 1.38031 0.301292
GE.JAGI.BHZ. 2021-04-25T22:38:28.22 10.0 negative automatic P 270 67.2899 -1.16525 0.29943
AU.GIRL.BHZ.00 2021-04-25T22:38:03.58 10.0 negative automatic P 255 63.0825 1.18775 0.372897
II.KAPI.BHZ.00 2021-04-25T22:38:03.90 10.0 negative automatic P 275 63.3199 -0.0808981 0.356756
IU.CASY.BHZ.00 2021-04-25T22:38:03.62 10.0 positive automatic P 205 63.2286 0.289503 0.366482
GE.LUWI.BHZ. 2021-04-25T22:37:56.12 10.0 negative automatic P 281 62.0863 0.317792 0.334313
AU.MORW.BHZ. 2021-04-25T22:37:42.87 10.0 negative automatic P 248 60.186 -0.251505 0.41869
GE.TNTI.BHZ. 2021-04-25T22:37:33.02 10.0 negative automatic P 285 58.6917 0.141928 0.43031
GE.SANI.BHZ. 2021-04-25T22:37:32.82 10.0 negative automatic P 281 58.7402 -0.389955 0.429601
IU.NWAO.BHZ.00 2021-04-25T22:37:32.12 10.0 negative automatic P 244 58.6128 -0.277666 0.441989
IU.MBWA.BHZ.00 2021-04-25T22:37:31.22 10.0 negative automatic P 258 58.4631 -0.113508 0.444239
GE.SOEI.BHZ. 2021-04-25T22:37:25.97 10.0 negative automatic P 272 57.4565 1.46724 0.418671
IU.SBA.BHZ.00 2021-04-25T22:37:22.32 10.0 negative automatic P 184 56.7345 3.03311 0.454023
GT.VNDA.BHZ.00 2021-04-25T22:37:21.75 10.0 negative automatic P 185 56.7973 2.01174 0.442669
GE.BNDI.BHZ. 2021-04-25T22:37:00.87 10.0 negative automatic P 280 54.1642 -0.136082 0.487505
AU.FITZ.BHZ. 2021-04-25T22:36:58.68 10.0 negative automatic P 263 53.7647 0.530052 0.505427
GE.FAKI.BHZ. 2021-04-25T22:36:49.87 10.0 negative automatic P 284 52.6939 -0.49159 0.5104
GE.SAUI.BHZ. 2021-04-25T22:36:42.87 10.0 negative automatic P 277 51.5609 0.837276 0.540982
IU.GUMO.BHZ.00 2021-04-25T22:36:40.85 10.0 negative automatic P 310 51.3945 0.0334609 0.543716
AU.MTN.BHZ.00 2021-04-25T22:36:30.55 10.0 negative automatic P 271 50.0917 -0.555374 0.552209
AU.WRKA.BHZ.00 2021-04-25T22:36:30.23 10.0 negative automatic P 255 50.0067 -0.327017 0.573611
AU.FORT.BHZ.00 2021-04-25T22:36:27.25 10.0 negative automatic P 247 49.6484 -0.536005 0.579717
NZ.KHZ.HHZ.10 2021-04-25T22:36:23.25 10.0 positive automatic S 199 22.2263 -0.0867598 0
AU.KDU.BHZ.00 2021-04-25T22:36:21.78 10.0 negative automatic P 272 48.8943 -0.294165 0.565425
G.KIP.BHZ.00 2021-04-25T22:36:06.77 10.0 positive automatic P 25 46.8832 0.0722403 0.613153
IU.POHA.BHZ.00 2021-04-25T22:36:03.52 10.0 positive automatic P 28 46.4177 0.0950673 0.628661
GE.GENI.BHZ. 2021-04-25T22:35:58.32 10.0 positive automatic P 289 45.7657 0.301109 0.611142
II.WRAB.BHZ.00 2021-04-25T22:35:54.07 10.0 negative automatic P 263 45.3204 -0.520799 0.664026
IU.SNZO.BHZ.00 2021-04-25T22:35:51.12 10.0 positive automatic S 198 20.8681 -10.1275 0
IU.WAKE.BHZ.00 2021-04-25T22:35:41.97 10.0 negative automatic P 337 43.944 -1.71485 0.681284
AU.HTT.BHZ. 2021-04-25T22:35:15.95 10.0 positive automatic P 243 40.4935 -0.0851938 0.765133
G.TAOE.BHZ.00 2021-04-25T22:34:54.52 10.0 positive automatic P 76 37.6537 1.94546 0.785739
II.TAU.BHZ.00 2021-04-25T22:34:42.67 10.0 positive automatic P 226 36.472 0.135815 0.797878
AU.QLP.BHZ. 2021-04-25T22:34:35.72 10.0 negative automatic P 254 35.592 0.614267 0.844768
AU.RABL.BHZ.00 2021-04-25T22:34:25.60 10.0 negative automatic P 296 34.6258 -1.28355 0.834648
II.KWJN.BHZ.00 2021-04-25T22:34:24.85 10.0 negative automatic P 332 34.4587 -0.558759 0.818971
IU.CTAO.BHZ.00 2021-04-25T22:34:23.00 10.0 positive automatic P 266 34.2934 -0.0562246 0.893293
AU.MILA.BHZ.00 2021-04-25T22:34:13.70 10.0 negative automatic P 235 33.0322 0.429728 0.909348
G.CAN.BHZ.00 2021-04-25T22:34:10.55 10.0 negative automatic P 238 32.6504 0.602346 0.895742
AU.RIV.BHZ. 2021-04-25T22:33:52.60 10.0 negative automatic P 240 30.5393 1.18426 0.752693
IU.XMAS.BHZ.00 2021-04-25T22:33:51.30 10.0 positive automatic P 41 30.4397 0.760786 0.943022
AU.ARMA.BHZ. 2021-04-25T22:33:43.07 10.0 negative automatic P 246 29.4101 1.40691 0.963855
AU.EIDS.BHZ. 2021-04-25T22:33:41.25 10.0 positive automatic P 256 29.437 -0.502128 0.97561
NZ.ODZ.HHZ.10 2021-04-25T22:33:06.24 10.0 positive automatic P 201 25.5007 -0.558226 0.980392
IU.HNR.BHZ.00 2021-04-25T22:33:04.15 10.0 negative automatic P 295 25.2913 -0.738236 0.851064
IU.TARA.BHZ.00 2021-04-25T22:33:01.40 10.0 negative automatic P 336 25.0227 -1.05675 0.963855
AU.LHI.BHZ.00 2021-04-25T22:32:50.53 10.0 negative automatic P 240 23.5046 1.80564 0.952381
NZ.KHZ.HHZ.10 2021-04-25T22:32:33.72 10.0 positive automatic P 199 22.2263 -3.35632 0.97561
IU.SNZO.BHZ.00 2021-04-25T22:32:20.65 10.0 negative automatic P 198 20.8681 -3.2795 0.963855
G.SANVU.BHZ.00 2021-04-25T22:31:35.60 10.0 negative automatic P 290 16.1986 1.97738 0.930233
IU.RAR.BHZ.00 2021-04-25T22:31:34.02 10.0 positive automatic P 92 16.0294 2.25303 0.952381
NZ.OUZ.HHZ.10 2021-04-25T22:31:30.84 10.0 negative automatic P 209 15.874 0.780085 0.980392
IU.RAO.BHZ.00 2021-04-25T22:31:10.27 10.0 positive automatic S 186 7.6419 -4.02427 0
IU.FUNA.BHZ.00 2021-04-25T22:31:03.67 10.0 positive automatic P 344 13.6251 -0.0356493 0.898876
IU.AFI.BHZ.00 2021-04-25T22:30:03.37 10.0 positive automatic P 34 9.195 -4.83768 0.43956
IU.RAO.BHZ.00 2021-04-25T22:29:45.15 10.0 negative automatic P 186 7.6419 -3.10334 0.43956
II.MSVF.BHZ.00 2021-04-25T22:29:30.87 10.0 positive automatic P 309 6.079 2.38626 0.952381
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