Early-est:     Hokkaido, Japan Region    2025.12.09-05:15:51.18    q:C      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 [21]    Mwp: - [0]    Mwpd: - [0] Region: Hokkaido, Japan Region Origin Time: 2025.12.09-05:15:51.18 UTC Hypocenter: lat: 41.48°  lon: 142.54°  [+/-26km]    depth: 16km  [+/-18km] Location Quality: qualityCode:  C     stdErr: 1.5s   assocPhases: 60   usedPhases: 29 minDist: 0.7°   maxDist: 145.4°   AzGap: 153°   2ndAzGap: 170°   atten: -0.60 [+/-0.26] Location Uncertainty: 68%ConfEllipse:   minHorUnc: 14km   maxHorUnc: 26km   azMaxHorUnc: 128° 68%ConfEllipsoid:   semiMajorAxisLength: 32km   majorAxisAzimuth: 128°   majorAxisPlunge: 8°   semiIntermediateAxisLength: 19km   intermediateAxisAzimuth: 30°   intermediateAxisPlunge: 42°   semiMinorAxisLength: 16km Tsunamigeneic Assesment: Discriminants: Prob Underwater: >99% T50Ex: 0.4 [15]    Td: -s [0]    Td*T50Ex: - [0]    To: 4.5s [11] Closest plate boundaries:    Pacific \ Okhotsk [subduction zone]: distance: ~180km    Okhotsk / Pacific [subduction zone]: distance: ~180km Subduction geometry:    Zone: Kamchatka/Kurils/Japan    Slab depth at epicenter: 50km Decision table (TEST!): Event type: Subduction Zone Other Thrust/Normal Strike-slip Compatible close plate boundary?:  YES (180km)  no  no Prob underwater:  >99%  >99%  >99% Td*T50Ex:    -    -    - Td*To:      -      -      - Mwp magnitude:        -        -        - Hypocenter depth:        16km        16km        16km Slab depth at epicenter:        50km        -        -

First-motion Focal Mechanism (FMAMP_POLARITY):    (Warning: VERY UNRELIABLE SOLUTION, qualityCode=D) Nodal Plane 1: strike: 155°   dip: 25°   rake: -178° Nodal Plane 2: strike: 63°   dip: 89°   rake: -65° Quality: azimuthalGap: -1°   stationPolarityCount: 22   misfitWeightCount: 5.3   misfit: 0.09   stationDistributionRatio: 0.38   meanDistP: 49.7   meanDistT: 47.1   qualityCode: D Method: methodID: smi:net.alomax/focalmec/fmamp_0.0.5X_2016.06.14/_polarity
First-motion Focal Mechanism (HASH):    (No solution available) Nodal Plane 1: strike: 999°   dip: 99°   rake: 999° Nodal Plane 2: strike: 324°   dip: 13°   rake: 135° Quality: azimuthalGap: 152°   stationPolarityCount: 22   misfit: 0.99   stationDistributionRatio: 0.00   rmsAngDiffAccPref: 0.00   fracAcc30degPref: 0.00   qualityCode: E 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/1765257352399
Event info last updated: 2025.12.09-06:16:05 UTC
Event first association/location: 2025.12.09-05:27:34 UTC
Software: Early-est 1.2.0 (2016.06.27)
Agency: KOERI