Early-est:     Tonga Islands Region    2026.06.21-17:29:49.18    q:B      mb:4.6*    Mwp:-    Mwpd:-    Td*T50Ex:-     fmamp_polarity:./hypo.1782062988599.mech.fmamp_polarity.thumb.jpg     fmamp_polarity_waveform:./hypo.1782062988599.mech.fmamp_polarity_waveform.thumb.jpg     hash:./hypo.1782062988599.mech.hash.thumb.jpg

Automatic solution - this event has not been reviewed by a seismologist
Automatically determined event information may be incorrect!

Earthquake Details:
Magnitude: mb: 4.6* [14]    Mwp: - [0]    Mwpd: - [0]
Region: Tonga Islands Region
Origin Time: 2026.06.21-17:29:49.18 UTC
Hypocenter: lat: -18.70°  lon: -172.55°  [+/-25km]    depth: 122km  [+/-26km]
Location Quality: qualityCode:  B     stdErr: 2.0s   assocPhases: 38   usedPhases: 19
minDist: 2.5°   maxDist: 150.6°   AzGap: 90°   2ndAzGap: 177°   atten: -1.85 [+/-0.33]
Location Uncertainty: 68%ConfEllipse:   minHorUnc: 14km   maxHorUnc: 25km   azMaxHorUnc: 22°
68%ConfEllipsoid:   semiMajorAxisLength: 32km   majorAxisAzimuth: 25°   majorAxisPlunge: 28°   semiIntermediateAxisLength: 24km   intermediateAxisAzimuth: 173°   intermediateAxisPlunge: 58°   semiMinorAxisLength: 16km
Tsunamigeneic Assesment:
Discriminants: Prob Underwater: >99%
T50Ex: 0.4 [6]    Td: -s [0]    Td*T50Ex: - [0]    To: 3.0s [5]
Closest plate boundaries:
   Tonga / Pacific [subduction zone]: distance: ~30km
Subduction geometry: none or not available
Decision table (TEST!):
Event type: Subduction Zone Other Thrust/Normal Strike-slip
Compatible close plate boundary?:
 YES (30km)
 no
 no
Prob underwater:
 >99%
 >99%
 >99%
Td*T50Ex:
   -
   -
   -
Td*To:
     -
     -
     -
Mwp magnitude:
       -
       -
       -
Hypocenter depth:
       122km
       122km
       122km
Slab depth at epicenter:
       n/a
       -
       -
Tsunami and Rupture predictions (TEST!): No prediction: Event too small (Mwp<7.0) or too few Mwp readings (N<20)
./hypo.1782062988599.map.jpg

First-motion Focal Mechanism (FMAMP_POLARITY):    (Warning: VERY UNRELIABLE SOLUTION, qualityCode=D)
Nodal Plane 1: strike: 120°   dip: 19°   rake: -178°
Nodal Plane 2: strike: 28°   dip: 89°   rake: -71°
Quality: azimuthalGap: -1°   stationPolarityCount: 16   misfitWeightCount: 4.2   misfit: 0.03   stationDistributionRatio: 0.31   meanDistP: 50.7   meanDistT: 52.8   qualityCode: D
Method: methodID: smi:net.alomax/focalmec/fmamp_0.0.5X_2016.06.14/_polarity
./hypo.1782062988599.mech.fmamp_polarity.mechanism.jpg
First-motion Focal Mechanism (FMAMP_POLARITY_WAVEFORM):    (No solution available)
Nodal Plane 1: strike: 0°   dip: 0°   rake: 0°
Nodal Plane 2: strike: 270°   dip: 90°   rake: 90°
Quality: azimuthalGap: -1°   stationPolarityCount: 0   misfitWeightCount: -1.0   misfit: -1.00   stationDistributionRatio: -1.00   meanDistP: -1.0   meanDistT: -1.0   qualityCode: X
Method: methodID: smi:net.alomax/focalmec/fmamp_0.0.5X_2016.06.14/_polarity_waveform
./hypo.1782062988599.mech.fmamp_polarity_waveform.mechanism.jpg
First-motion Focal Mechanism (HASH):    (No solution available)
Nodal Plane 1: strike: 999°   dip: 99°   rake: 999°
Nodal Plane 2: strike: 324°   dip: 13°   rake: 135°
Quality: azimuthalGap: 219°   stationPolarityCount: 16   misfit: 0.99   stationDistributionRatio: 0.71   rmsAngDiffAccPref: 41.69   fracAcc30degPref: 0.00   qualityCode: E
Method: methodID: smi:gov.usgs/focalmec/HASH_1.2
./hypo.1782062988599.mech.hash.mechanism.jpg

Event ID: smi:alomax.net_BETA/author/ee/event/1782062988599
Event info last updated: 2026.06.21-18:28:01 UTC
Event first association/location: 2026.06.21-17:35:01 UTC
Software: Early-est 1.2.10 (2024.02.23)
Agency: alomax.net_BETA