Early-est:     Near S. Coast of Honshu, Japan    2025.07.31-23:24:15.94    q:B      mb:4.7*    Mwp:-    Mwpd:-    Td*T50Ex:-     fmamp_polarity:./hypo.1754004258741.mech.fmamp_polarity.thumb.jpg     fmamp_polarity_waveform:./hypo.1754004258741.mech.fmamp_polarity_waveform.thumb.jpg     hash:./hypo.1754004258741.mech.hash.thumb.jpg

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

Earthquake Details:
Magnitude: mb: 4.7* [56]    Mwp: - [0]    Mwpd: - [0]
Region: Near S. Coast of Honshu, Japan
Origin Time: 2025.07.31-23:24:15.94 UTC
Hypocenter: lat: 34.39°  lon: 137.09°  [+/-22km]    depth: 318km  [+/-26km]
Location Quality: qualityCode:  B     stdErr: 1.6s   assocPhases: 95   usedPhases: 69
minDist: 1.0°   maxDist: 156.2°   AzGap: 46°   2ndAzGap: 65°   atten: -0.92 [+/-0.18]
Location Uncertainty: 68%ConfEllipse:   minHorUnc: 19km   maxHorUnc: 22km   azMaxHorUnc: 113°
68%ConfEllipsoid:   semiMajorAxisLength: 30km   majorAxisAzimuth: 84°   majorAxisPlunge: 44°   semiIntermediateAxisLength: 27km   intermediateAxisAzimuth: 324°   intermediateAxisPlunge: 28°   semiMinorAxisLength: 20km
Tsunamigeneic Assesment:
Discriminants: Prob Underwater: >99%
T50Ex: 0.0 [31]    Td: 0.5Xs [1]    Td*T50Ex: - [0]    To: 1.2s [31]
Closest plate boundaries:
   Amur / Philippine Sea [subduction zone]: distance: ~110km
   Okhotsk - Philippine Sea [continental convergent boundary]: distance: ~160km
   Okhotsk - Amur [continental convergent boundary]: distance: ~160km
   Pacific \ Okhotsk [subduction zone]: distance: ~440km
   Philippine Sea / Pacific [subduction zone]: distance: ~440km
Subduction geometry:    Zone: Izu-Bonin: DEBUG: error: [Errno 2] No such file or directory: 'gmt'    Slab depth at epicenter: error: evaluating slab depth: -999.9
Decision table (TEST!):
Event type: Subduction Zone Other Thrust/Normal Strike-slip
Compatible close plate boundary?:
 YES (110km)
 no
 no
Prob underwater:
 >99%
 >99%
 >99%
Td*T50Ex:
   -
   -
   -
Td*To:
     -
     -
     -
Mwp magnitude:
       -
       -
       -
Hypocenter depth:
       318km
       318km
       318km
Slab depth at epicenter:
       n/a
       -
       -
Tsunami and Rupture predictions (TEST!): No prediction: Event too small (Mwp<7.0) or too few Mwp readings (N<20)
./hypo.1754004258741.map.jpg

First-motion Focal Mechanism (FMAMP_POLARITY):
Nodal Plane 1: strike: 127°   dip: 71°   rake: 179°
Nodal Plane 2: strike: 217°   dip: 89°   rake: 19°
Quality: azimuthalGap: -1°   stationPolarityCount: 56   misfitWeightCount: 22.0   misfit: 0.14   stationDistributionRatio: 0.53   meanDistP: 28.2   meanDistT: 21.7   qualityCode: B
Method: methodID: smi:net.alomax/focalmec/fmamp_0.0.5X_2016.06.14/_polarity
./hypo.1754004258741.mech.fmamp_polarity.mechanism.jpg
First-motion Focal Mechanism (FMAMP_POLARITY_WAVEFORM):    (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/_polarity_waveform
./hypo.1754004258741.mech.fmamp_polarity_waveform.mechanism.jpg
First-motion Focal Mechanism (HASH):
Nodal Plane 1: strike: 126°   dip: 72°   rake: 174°
Nodal Plane 2: strike: 218°   dip: 85°   rake: 18°
Quality: azimuthalGap: 43°   stationPolarityCount: 56   misfit: 0.23   stationDistributionRatio: 0.78   rmsAngDiffAccPref: 7.23   fracAcc30degPref: 1.00   qualityCode: B
Method: methodID: smi:gov.usgs/focalmec/HASH_1.2
./hypo.1754004258741.mech.hash.mechanism.jpg

Event ID: smi:alomax.net_BETA/author/ee/event/1754004258741
Event info last updated: 2025.08.01-00:23:00 UTC
Event first association/location: 2025.07.31-23:27:01 UTC
Software: Early-est 1.2.10 (2024.02.23)
Agency: alomax.net_BETA