Early-est: Off East Coast of Honshu, Japan 2025.11.09-00:17:35.66 q:B mb:5.1 Mwp:5.2 Mwpd:- Td*T50Ex:1.3 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: 5.1 [59] Mwp: 5.2 [5] Mwpd: - [0]
Region:	Off East Coast of Honshu, Japan
Origin Time:	2025.11.09-00:17:35.66 UTC
Hypocenter:	lat: 39.44° lon: 143.02° [+/-12km] depth: 16km [+/-11km]
Location Quality:	qualityCode: B stdErr: 1.6s assocPhases: 97 usedPhases: 61 minDist: 2.0° maxDist: 143.5° AzGap: 187° 2ndAzGap: 191° atten: -0.78 [+/-0.31]
Location Uncertainty:	68%ConfEllipse: minHorUnc: 9km maxHorUnc: 12km azMaxHorUnc: 103° 68%ConfEllipsoid: semiMajorAxisLength: 14km majorAxisAzimuth: 103° majorAxisPlunge: 2° semiIntermediateAxisLength: 12km intermediateAxisAzimuth: 11° intermediateAxisPlunge: 53° semiMinorAxisLength: 11km

Tsunamigeneic Assesment:

Discriminants:

Prob Underwater: >99%
T50Ex: 0.6 [44]    Td: 2.3s [6]    Td*T50Ex: 1.3 [6]    To: 27.8s [38]
Closest plate boundaries:
   Pacific \ Okhotsk [subduction zone]: distance: ~100km
   Okhotsk / Pacific [subduction zone]: distance: ~200km
Subduction geometry:    Zone: Kamchatka/Kurils/Japan    Slab depth at epicenter: 21km

Decision table (TEST!):

Event type:

Subduction Zone

Other Thrust/Normal

Strike-slip

Compatible close plate boundary?:

YES (100km)

Prob underwater:

>99%

Td*T50Ex:

1.3

Td*To:

63.9

Mwp magnitude:

5.2

Hypocenter depth:

16km

Slab depth at epicenter:

21km

First-motion Focal Mechanism (FMAMP_POLARITY): (Warning: Unreliable solution, qualityCode=C)
Nodal Plane 1:	strike: 56° dip: 43° rake: -21°
Nodal Plane 2:	strike: 162° dip: 76° rake: -131°
Quality:	azimuthalGap: -1° stationPolarityCount: 63 misfitWeightCount: 10.0 misfit: 0.09 stationDistributionRatio: 0.36 meanDistP: 31.3 meanDistT: 32.5 qualityCode: C
Method:	methodID: smi:net.alomax/focalmec/fmamp_0.0.5X_2016.06.14/_polarity

./hypo.1762647459277.mech.fmamp_polarity.mechanism.jpg

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: 151° stationPolarityCount: 63 misfit: 0.99 stationDistributionRatio: 0.00 rmsAngDiffAccPref: 0.00 fracAcc30degPref: 0.00 qualityCode: E
Method:	methodID: smi:gov.usgs/focalmec/HASH_1.2

./hypo.1762647459277.mech.hash.mechanism.jpg

First-motion Focal Mechanism (FMAMP_AMP_AREF): (Warning: VERY UNRELIABLE SOLUTION, qualityCode=D)
Nodal Plane 1:	strike: 144° dip: 31° rake: -15°
Nodal Plane 2:	strike: 247° dip: 82° rake: -120°
Quality:	azimuthalGap: -1° stationPolarityCount: 10 misfitWeightCount: 3.9 misfit: 9999.90 stationDistributionRatio: 0.44 meanDistP: 42.5 meanDistT: 31.1 qualityCode: D
Method:	methodID: smi:net.alomax/focalmec/fmamp_0.0.5X_2016.06.14/_amp_aref

./hypo.1762647459277.mech.fmamp_amp_aref.mechanism.jpg

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

./hypo.1762647459277.mech.fmamp_amp_mwp.mechanism.jpg

Event ID: smi:KOERI/ee/event/1762647459277
Event info last updated: 2025.11.09-01:17:57 UTC
Event first association/location: 2025.11.09-00:24:53 UTC
Software: Early-est 1.2.0 (2016.06.27)
Agency: KOERI

Early-est: Off East Coast of Honshu, Japan 2025.11.09-00:17:35.66 q:B mb:5.1 Mwp:5.2 Mwpd:- Td*T50Ex:1.3 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!

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