Early-est:     Hokkaido, Japan Region    2025.12.08-17:58:27.02    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 [35]    Mwp: - [0]    Mwpd: - [0] Region: Hokkaido, Japan Region Origin Time: 2025.12.08-17:58:27.02 UTC Hypocenter: lat: 41.01°  lon: 143.35°  [+/-15km]    depth: 20km  [+/-13km] Location Quality: qualityCode:  B     stdErr: 1.5s   assocPhases: 73   usedPhases: 41 minDist: 1.0°   maxDist: 153.6°   AzGap: 108°   2ndAzGap: 172°   atten: -0.57 [+/-0.22] Location Uncertainty: 68%ConfEllipse:   minHorUnc: 13km   maxHorUnc: 15km   azMaxHorUnc: 98° 68%ConfEllipsoid:   semiMajorAxisLength: 19km   majorAxisAzimuth: 98°   majorAxisPlunge: 1°   semiIntermediateAxisLength: 16km   intermediateAxisAzimuth: 188°   intermediateAxisPlunge: 4°   semiMinorAxisLength: 13km Tsunamigeneic Assesment: Discriminants: Prob Underwater: >99% T50Ex: 0.4 [29]    Td: -s [0]    Td*T50Ex: - [0]    To: 1.5s [22] Closest plate boundaries:    Pacific \ Okhotsk [subduction zone]: distance: ~90km    Okhotsk / Pacific [subduction zone]: distance: ~90km Subduction geometry:    Zone: Kamchatka/Kurils/Japan    Slab depth at epicenter: 25km Decision table (TEST!): Event type: Subduction Zone Other Thrust/Normal Strike-slip Compatible close plate boundary?:  YES (90km)  no  no Prob underwater:  >99%  >99%  >99% Td*T50Ex:    -    -    - Td*To:      -      -      - Mwp magnitude:        -        -        - Hypocenter depth:        20km        20km        20km Slab depth at epicenter:        25km        -        -

First-motion Focal Mechanism (FMAMP_POLARITY):    (Warning: Unreliable solution, qualityCode=C) Nodal Plane 1: strike: 44°   dip: 23°   rake: -131° Nodal Plane 2: strike: 268°   dip: 73°   rake: -74° Quality: azimuthalGap: -1°   stationPolarityCount: 35   misfitWeightCount: 6.7   misfit: 0.09   stationDistributionRatio: 0.60   meanDistP: 31.5   meanDistT: 28.9   qualityCode: C Method: methodID: smi:net.alomax/focalmec/fmamp_0.0.5X_2016.06.14/_polarity
First-motion Focal Mechanism (HASH):    (Warning: Unreliable solution, qualityCode=C) Nodal Plane 1: strike: 233°   dip: 67°   rake: -86° Nodal Plane 2: strike: 44°   dip: 24°   rake: -98° Quality: azimuthalGap: 107°   stationPolarityCount: 35   misfit: 0.26   stationDistributionRatio: 0.60   rmsAngDiffAccPref: 26.13   fracAcc30degPref: 0.78   qualityCode: C 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: 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/_amp_aref
First-motion Focal Mechanism (FMAMP_AMP_MWP):    (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/_amp_mwp

Event ID: smi:KOERI/ee/event/1765216709759
Event info last updated: 2025.12.08-18:58:37 UTC
Event first association/location: 2025.12.08-18:07:40 UTC
Software: Early-est 1.2.0 (2016.06.27)
Agency: KOERI