Early-est:     Tonga Islands    2026.09.29-12:40:36.55    q:A      mb:5.3*    Mwp:5.8    Mwpd:-    Td*T50Ex:-     fmamp_polarity:./hypo.1790685640069.mech.fmamp_polarity.thumb.jpg     fmamp_polarity_waveform:./hypo.1790685640069.mech.fmamp_polarity_waveform.thumb.jpg     hash:./hypo.1790685640069.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: 5.3* [61]    Mwp: 5.8 [4]    Mwpd: 6.0Xinv [4]
Region: Tonga Islands
Origin Time: 2026.09.29-12:40:36.55 UTC
Hypocenter: lat: -20.48°  lon: -173.77°  [+/-13km]    depth: 18km  [+/-13km]
Location Quality: qualityCode:  A     stdErr: 1.7s   assocPhases: 119   usedPhases: 88
minDist: 3.9°   maxDist: 162.5°   AzGap: 45°   2ndAzGap: 90°   atten: -1.26 [+/-0.24]
Location Uncertainty: 68%ConfEllipse:   minHorUnc: 12km   maxHorUnc: 13km   azMaxHorUnc: 159°
68%ConfEllipsoid:   semiMajorAxisLength: 16km   majorAxisAzimuth: 140°   majorAxisPlunge: 23°   semiIntermediateAxisLength: 15km   intermediateAxisAzimuth: 39°   intermediateAxisPlunge: 22°   semiMinorAxisLength: 12km
Tsunamigeneic Assesment:
Discriminants: Prob Underwater: >99%
T50Ex: 0.4 [56]    Td: 2.4Xs [3]    Td*T50Ex: - [0]    To: 6.5s [53]
Closest plate boundaries:
   Tonga / Pacific [subduction zone]: distance: ~40km
   Tonga - Niuafo'ou [continental convergent boundary]: distance: ~170km
Subduction geometry:    Zone: Kermadec-Tonga: DEBUG: error: [Errno 2] No such file or directory: 'gmt'    Slab depth at epicenter: error: evaluating slab depth: -999.9
Decision table (TEST!):
Event type: Subduction Zone Other Thrust/Normal Strike-slip
Compatible close plate boundary?:
 YES (40km)
 no
 no
Prob underwater:
 >99%
 >99%
 >99%
Td*T50Ex:
   -
   -
   -
Td*To:
     -
     -
     -
Mwp magnitude:
       5.8
       5.8
       5.8
Hypocenter depth:
       18km
       18km
       18km
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.1790685640069.map.jpg

First-motion Focal Mechanism (FMAMP_POLARITY):    (Warning: Unreliable solution, qualityCode=C)
Nodal Plane 1: strike: 37°   dip: 38°   rake: 121°
Nodal Plane 2: strike: 180°   dip: 58°   rake: 68°
Quality: azimuthalGap: -1°   stationPolarityCount: 52   misfitWeightCount: 7.2   misfit: 0.07   stationDistributionRatio: 0.47   meanDistP: 44.0   meanDistT: 34.2   qualityCode: C
Method: methodID: smi:net.alomax/focalmec/fmamp_0.0.5X_2016.06.14/_polarity
./hypo.1790685640069.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.1790685640069.mech.fmamp_polarity_waveform.mechanism.jpg
First-motion Focal Mechanism (HASH):    (Warning: VERY UNRELIABLE SOLUTION, qualityCode=D)
Nodal Plane 1: strike: 4°   dip: 82°   rake: 144°
Nodal Plane 2: strike: 100°   dip: 54°   rake: 10°
Quality: azimuthalGap: 116°   stationPolarityCount: 52   misfit: 0.26   stationDistributionRatio: 0.66   rmsAngDiffAccPref: 51.60   fracAcc30degPref: 0.39   qualityCode: D
Method: methodID: smi:gov.usgs/focalmec/HASH_1.2
./hypo.1790685640069.mech.hash.mechanism.jpg

Event ID: smi:alomax.net_BETA/author/ee/event/1790685640069
Event info last updated: 2026.09.29-13:39:01 UTC
Event first association/location: 2026.09.29-12:46:03 UTC
Software: Early-est 1.2.10 (2024.02.23)
Agency: alomax.net_BETA