Early-est:     Southeast of Honshu, Japan    2026.10.08-18:32:01.43    q:B      mb:4.9    Mwp:-    Mwpd:-    Td*T50Ex:-     fmamp_polarity:     hash:     fmamp_amp_aref:     fmamp_amp_mwp:

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

Earthquake Details: Magnitude: mb: 4.9 [24]    Mwp: - [0]    Mwpd: - [0] Region: Southeast of Honshu, Japan Origin Time: 2026.10.08-18:32:01.43 UTC Hypocenter: lat: 30.74°  lon: 141.04°  [+/-6km]    depth: 77km  [+/-7km] Location Quality: qualityCode:  B     stdErr: 1.5s   assocPhases: 56   usedPhases: 30 minDist: 2.6°   maxDist: 149.7°   AzGap: 71°   2ndAzGap: 101°   atten: -1.15 [+/-0.22] Location Uncertainty: 68%ConfEllipse:   minHorUnc: 5km   maxHorUnc: 6km   azMaxHorUnc: 55° 68%ConfEllipsoid:   semiMajorAxisLength: 8km   majorAxisAzimuth: 53°   majorAxisPlunge: 43°   semiIntermediateAxisLength: 7km   intermediateAxisAzimuth: 241°   intermediateAxisPlunge: 47°   semiMinorAxisLength: 7km Tsunamigeneic Assesment: Discriminants: Prob Underwater: >99% T50Ex: 0.4 [12]    Td: 1.2Xs [1]    Td*T50Ex: - [0]    To: 1.3s [6] Closest plate boundaries:    Philippine Sea / Pacific [subduction zone]: distance: ~110km Subduction geometry:    Zone: Izu-Bonin    Slab depth at epicenter: 56km Decision table (TEST!): Event type: Subduction Zone Other Thrust/Normal Strike-slip Compatible close plate boundary?:  YES (110km)  no  no Prob underwater:  >99%  >99%  >99% Td*T50Ex:    -    -    - Td*To:      -      -      - Mwp magnitude:        -        -        - Hypocenter depth:        77km        77km        77km Slab depth at epicenter:        56km        -        -

First-motion Focal Mechanism (FMAMP_POLARITY):    (Warning: VERY UNRELIABLE SOLUTION, qualityCode=D) Nodal Plane 1: strike: 284°   dip: 47°   rake: 128° Nodal Plane 2: strike: 55°   dip: 55°   rake: 56° Quality: azimuthalGap: -1°   stationPolarityCount: 24   misfitWeightCount: 7.0   misfit: 0.09   stationDistributionRatio: 0.54   meanDistP: 34.4   meanDistT: 36.6   qualityCode: D Method: methodID: smi:net.alomax/focalmec/fmamp_0.0.5X_2016.06.14/_polarity
First-motion Focal Mechanism (HASH):    (Warning: VERY UNRELIABLE SOLUTION, qualityCode=D) Nodal Plane 1: strike: 290°   dip: 52°   rake: 138° Nodal Plane 2: strike: 49°   dip: 58°   rake: 47° Quality: azimuthalGap: 90°   stationPolarityCount: 24   misfit: 0.32   stationDistributionRatio: 0.56   rmsAngDiffAccPref: 35.00   fracAcc30degPref: 0.56   qualityCode: D Method: methodID: smi:gov.usgs/focalmec/HASH_1.2
First-motion Focal Mechanism (FMAMP_AMP_AREF):    (No solution available) Nodal Plane 1: strike: 0°   dip: 0°   rake: nan° Nodal Plane 2: strike: nan°   dip: nan°   rake: nan° 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/_amp_aref
First-motion Focal Mechanism (FMAMP_AMP_MWP):    (No solution available) Nodal Plane 1: strike: 0°   dip: 0°   rake: nan° Nodal Plane 2: strike: nan°   dip: nan°   rake: nan° 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/_amp_mwp

Event ID: smi:KOERI/ee/event/1791484320890
Event info last updated: 2026.10.08-19:33:02 UTC
Event first association/location: 2026.10.08-19:05:03 UTC
Software: Early-est 1.2.0 (2016.06.27)
Agency: KOERI