Early-est:     Hokkaido, Japan Region    2025.12.09-23:04:38.13    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 [22]    Mwp: - [0]    Mwpd: - [0] Region: Hokkaido, Japan Region Origin Time: 2025.12.09-23:04:38.13 UTC Hypocenter: lat: 41.48°  lon: 141.91°  [+/-15km]    depth: 16km  [+/-20km] Location Quality: qualityCode:  B     stdErr: 1.3s   assocPhases: 57   usedPhases: 25 minDist: 0.9°   maxDist: 153.7°   AzGap: 134°   2ndAzGap: 152°   atten: -0.71 [+/-0.16] Location Uncertainty: 68%ConfEllipse:   minHorUnc: 13km   maxHorUnc: 15km   azMaxHorUnc: 115° 68%ConfEllipsoid:   semiMajorAxisLength: 22km   majorAxisAzimuth: 137°   majorAxisPlunge: 53°   semiIntermediateAxisLength: 17km   intermediateAxisAzimuth: 258°   intermediateAxisPlunge: 21°   semiMinorAxisLength: 15km Tsunamigeneic Assesment: Discriminants: Prob Underwater: >99% T50Ex: 0.3 [13]    Td: -s [0]    Td*T50Ex: - [0]    To: 1.6s [11] Closest plate boundaries:    Pacific \ Okhotsk [subduction zone]: distance: ~220km    Okhotsk / Pacific [subduction zone]: distance: ~220km Subduction geometry:    Zone: Kamchatka/Kurils/Japan    Slab depth at epicenter: 69km Decision table (TEST!): Event type: Subduction Zone Other Thrust/Normal Strike-slip Compatible close plate boundary?:  YES (220km)  no  no Prob underwater:  >99%  >99%  >99% Td*T50Ex:    -    -    - Td*To:      -      -      - Mwp magnitude:        -        -        - Hypocenter depth:        16km        16km        16km Slab depth at epicenter:        69km        -        -

First-motion Focal Mechanism (FMAMP_POLARITY):    (Warning: VERY UNRELIABLE SOLUTION, qualityCode=D) Nodal Plane 1: strike: 31°   dip: 24°   rake: -165° Nodal Plane 2: strike: 287°   dip: 84°   rake: -66° Quality: azimuthalGap: -1°   stationPolarityCount: 20   misfitWeightCount: 3.8   misfit: 0.10   stationDistributionRatio: 0.46   meanDistP: 43.9   meanDistT: 45.6   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: 160°   dip: 35°   rake: -108° Nodal Plane 2: strike: 2°   dip: 57°   rake: -78° Quality: azimuthalGap: 97°   stationPolarityCount: 20   misfit: 0.37   stationDistributionRatio: 0.58   rmsAngDiffAccPref: 46.01   fracAcc30degPref: 0.31   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/1765321479500
Event info last updated: 2025.12.10-00:04:45 UTC
Event first association/location: 2025.12.09-23:13:37 UTC
Software: Early-est 1.2.0 (2016.06.27)
Agency: KOERI