Early-est:     Hokkaido, Japan Region    2025.12.09-00:18:30.85    q:B      mb:4.8    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: 4.8 [38]    Mwp: - [0]    Mwpd: - [0] Region: Hokkaido, Japan Region Origin Time: 2025.12.09-00:18:30.85 UTC Hypocenter: lat: 41.22°  lon: 142.20°  [+/-19km]    depth: 52km  [+/-19km] Location Quality: qualityCode:  B     stdErr: 1.2s   assocPhases: 74   usedPhases: 51 minDist: 1.0°   maxDist: 145.0°   AzGap: 146°   2ndAzGap: 162°   atten: -0.77 [+/-0.20] Location Uncertainty: 68%ConfEllipse:   minHorUnc: 15km   maxHorUnc: 19km   azMaxHorUnc: 140° 68%ConfEllipsoid:   semiMajorAxisLength: 24km   majorAxisAzimuth: 145°   majorAxisPlunge: 25°   semiIntermediateAxisLength: 19km   intermediateAxisAzimuth: 256°   intermediateAxisPlunge: 37°   semiMinorAxisLength: 17km Tsunamigeneic Assesment: Discriminants: Prob Underwater: >99% T50Ex: 0.4 [20]    Td: -s [0]    Td*T50Ex: - [0]    To: 1.9s [15] Closest plate boundaries:    Pacific \ Okhotsk [subduction zone]: distance: ~190km    Okhotsk / Pacific [subduction zone]: distance: ~190km Subduction geometry:    Zone: Kamchatka/Kurils/Japan    Slab depth at epicenter: 59km Decision table (TEST!): Event type: Subduction Zone Other Thrust/Normal Strike-slip Compatible close plate boundary?:  YES (190km)  no  no Prob underwater:  >99%  >99%  >99% Td*T50Ex:    -    -    - Td*To:      -      -      - Mwp magnitude:        -        -        - Hypocenter depth:        52km        52km        52km Slab depth at epicenter:        59km        -        -

First-motion Focal Mechanism (FMAMP_POLARITY):    (Warning: Unreliable solution, qualityCode=C) Nodal Plane 1: strike: 71°   dip: 17°   rake: -33° Nodal Plane 2: strike: 193°   dip: 81°   rake: -104° Quality: azimuthalGap: -1°   stationPolarityCount: 48   misfitWeightCount: 7.8   misfit: 0.10   stationDistributionRatio: 0.53   meanDistP: 24.5   meanDistT: 29.1   qualityCode: C Method: methodID: smi:net.alomax/focalmec/fmamp_0.0.5X_2016.06.14/_polarity
First-motion Focal Mechanism (HASH): Nodal Plane 1: strike: 229°   dip: 64°   rake: -178° Nodal Plane 2: strike: 138°   dip: 88°   rake: -26° Quality: azimuthalGap: 125°   stationPolarityCount: 48   misfit: 0.24   stationDistributionRatio: 0.62   rmsAngDiffAccPref: 13.77   fracAcc30degPref: 0.97   qualityCode: B 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/1765239510473
Event info last updated: 2025.12.09-01:18:42 UTC
Event first association/location: 2025.12.09-00:28:42 UTC
Software: Early-est 1.2.0 (2016.06.27)
Agency: KOERI