Early-est:     Taiwan Region    2026.09.30-05:00:28.68    q:B      mb:5.4    Mwp:5.7*    Mwpd:-    Td*T50Ex:1.3     fmamp_polarity:./hypo.1790744434458.mech.fmamp_polarity.thumb.jpg     fmamp_polarity_waveform:./hypo.1790744434458.mech.fmamp_polarity_waveform.thumb.jpg     hash:./hypo.1790744434458.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: 5.4 [101]    Mwp: 5.7* [23]    Mwpd: 5.9Xinv [23]
Region: Taiwan Region
Origin Time: 2026.09.30-05:00:28.68 UTC
Hypocenter: lat: 23.81°  lon: 122.83°  [+/-31km]    depth: 15km  [+/-24km]
Location Quality: qualityCode:  B     stdErr: 1.9s   assocPhases: 187   usedPhases: 124
minDist: 0.7°   maxDist: 177.5°   AzGap: 56°   2ndAzGap: 61°   atten: -0.70 [+/-0.20]
Location Uncertainty: 68%ConfEllipse:   minHorUnc: 28km   maxHorUnc: 31km   azMaxHorUnc: 98°
68%ConfEllipsoid:   semiMajorAxisLength: 39km   majorAxisAzimuth: 98°   majorAxisPlunge: 6°   semiIntermediateAxisLength: 34km   intermediateAxisAzimuth: 7°   intermediateAxisPlunge: 1°   semiMinorAxisLength: 24km
Tsunamigeneic Assesment:
Discriminants: Prob Underwater: >99%
T50Ex: 0.5 [74]    Td: 2.8s [17]    Td*T50Ex: 1.3 [17]    To: 4.7s [73]
Closest plate boundaries:
   Okinawa - Philippine Sea [oceanic transform fault]: distance: ~40km
   Yangtze - Okinawa [continental rift boundary]: distance: ~120km
   Philippine Sea - Yangtze [continental transform fault]: distance: ~160km
   Okinawa / Philippine Sea [subduction zone]: distance: ~280km
Subduction geometry: none or not available
Decision table (TEST!):
Event type: Subduction Zone Other Thrust/Normal Strike-slip
Compatible close plate boundary?:
 no
 no
 YES (40km)
Prob underwater:
 >99%
 >99%
 >99%
Td*T50Ex:
   1.3
   1.3
   1.3
Td*To:
     13.2
     13.2
     13.2
Mwp magnitude:
       5.7*
       5.7*
       5.7*
Hypocenter depth:
       15km
       15km
       15km
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.1790744434458.map.jpg

First-motion Focal Mechanism (FMAMP_POLARITY):
Nodal Plane 1: strike: 19°   dip: 35°   rake: -149°
Nodal Plane 2: strike: 263°   dip: 73°   rake: -59°
Quality: azimuthalGap: -1°   stationPolarityCount: 94   misfitWeightCount: 19.6   misfit: 0.16   stationDistributionRatio: 0.49   meanDistP: 28.8   meanDistT: 32.1   qualityCode: B
Method: methodID: smi:net.alomax/focalmec/fmamp_0.0.5X_2016.06.14/_polarity
./hypo.1790744434458.mech.fmamp_polarity.mechanism.jpg
First-motion Focal Mechanism (FMAMP_POLARITY_WAVEFORM):    (Warning: Unreliable solution, qualityCode=C)
Nodal Plane 1: strike: 157°   dip: 1°   rake: -104°
Nodal Plane 2: strike: 351°   dip: 89°   rake: -90°
Quality: azimuthalGap: -1°   stationPolarityCount: 12   misfitWeightCount: 6.0   misfit: 0.05   stationDistributionRatio: 0.54   meanDistP: 44.0   meanDistT: 43.4   qualityCode: C
Method: methodID: smi:net.alomax/focalmec/fmamp_0.0.5X_2016.06.14/_polarity_waveform
./hypo.1790744434458.mech.fmamp_polarity_waveform.mechanism.jpg
First-motion Focal Mechanism (HASH):    (Warning: VERY UNRELIABLE SOLUTION, qualityCode=D)
Nodal Plane 1: strike: 315°   dip: 90°   rake: -119°
Nodal Plane 2: strike: 224°   dip: 29°   rake: -1°
Quality: azimuthalGap: 52°   stationPolarityCount: 94   misfit: 0.33   stationDistributionRatio: 0.67   rmsAngDiffAccPref: 35.53   fracAcc30degPref: 0.62   qualityCode: D
Method: methodID: smi:gov.usgs/focalmec/HASH_1.2
./hypo.1790744434458.mech.hash.mechanism.jpg

Event ID: smi:alomax.net_BETA/author/ee/event/1790744434458
Event info last updated: 2026.09.30-05:59:00 UTC
Event first association/location: 2026.09.30-05:05:06 UTC
Software: Early-est 1.2.10 (2024.02.23)
Agency: alomax.net_BETA