Early-est:     Near East Coast of Honshu, Japan    2026.08.08-17:57:58.47    q:B      mb:5.2    Mwp:5.8*    Mwpd:-    Td*T50Ex:1.8     fmamp_polarity:./hypo.1786211879249.mech.fmamp_polarity.thumb.jpg     fmamp_polarity_waveform:./hypo.1786211879249.mech.fmamp_polarity_waveform.thumb.jpg     hash:./hypo.1786211879249.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: 5.2 [95]    Mwp: 5.8* [39]    Mwpd: 6.0Xinv [37]
Region: Near East Coast of Honshu, Japan
Origin Time: 2026.08.08-17:57:58.47 UTC
Hypocenter: lat: 40.10°  lon: 142.37°  [+/-45km]    depth: 9km  [+/-40km]
Location Quality: qualityCode:  B     stdErr: 2.1s   assocPhases: 147   usedPhases: 89
minDist: 1.2°   maxDist: 144.4°   AzGap: 121°   2ndAzGap: 132°   atten: -0.99 [+/-0.14]
Location Uncertainty: 68%ConfEllipse:   minHorUnc: 38km   maxHorUnc: 45km   azMaxHorUnc: 97°
68%ConfEllipsoid:   semiMajorAxisLength: 56km   majorAxisAzimuth: 279°   majorAxisPlunge: 8°   semiIntermediateAxisLength: 48km   intermediateAxisAzimuth: 11°   intermediateAxisPlunge: 17°   semiMinorAxisLength: 38km
Tsunamigeneic Assesment:
Discriminants: Prob Underwater: >99%
T50Ex: 0.6 [72]    Td: 3.2s [4]    Td*T50Ex: 1.8 [4]    To: 31.5s [71]
Closest plate boundaries:
   Pacific \ Okhotsk [subduction zone]: distance: ~160km
   Okhotsk / Pacific [subduction zone]: distance: ~200km
Subduction geometry:    Zone: Kamchatka/Kurils/Japan: 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 (160km)
 no
 no
Prob underwater:
 >99%
 >99%
 >99%
Td*T50Ex:
   1.8
   1.8
   1.8
Td*To:
     100.8
     100.8
     100.8
Mwp magnitude:
       5.8*
       5.8*
       5.8*
Hypocenter depth:
       9km
       9km
       9km
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.1786211879249.map.jpg

First-motion Focal Mechanism (FMAMP_POLARITY):    (Warning: Unreliable solution, qualityCode=C)
Nodal Plane 1: strike: 156°   dip: 10°   rake: 64°
Nodal Plane 2: strike: 2°   dip: 81°   rake: 95°
Quality: azimuthalGap: -1°   stationPolarityCount: 77   misfitWeightCount: 7.9   misfit: 0.06   stationDistributionRatio: 0.54   meanDistP: 41.6   meanDistT: 36.1   qualityCode: C
Method: methodID: smi:net.alomax/focalmec/fmamp_0.0.5X_2016.06.14/_polarity
./hypo.1786211879249.mech.fmamp_polarity.mechanism.jpg
First-motion Focal Mechanism (FMAMP_POLARITY_WAVEFORM):    (Warning: VERY UNRELIABLE SOLUTION, qualityCode=D)
Nodal Plane 1: strike: 305°   dip: 34°   rake: 122°
Nodal Plane 2: strike: 89°   dip: 62°   rake: 71°
Quality: azimuthalGap: -1°   stationPolarityCount: 12   misfitWeightCount: 2.9   misfit: 0.02   stationDistributionRatio: 0.60   meanDistP: 51.9   meanDistT: 42.3   qualityCode: D
Method: methodID: smi:net.alomax/focalmec/fmamp_0.0.5X_2016.06.14/_polarity_waveform
./hypo.1786211879249.mech.fmamp_polarity_waveform.mechanism.jpg
First-motion Focal Mechanism (HASH):    (Warning: Unreliable solution, qualityCode=C)
Nodal Plane 1: strike: 16°   dip: 83°   rake: 95°
Nodal Plane 2: strike: 160°   dip: 9°   rake: 55°
Quality: azimuthalGap: 122°   stationPolarityCount: 74   misfit: 0.13   stationDistributionRatio: 0.67   rmsAngDiffAccPref: 34.26   fracAcc30degPref: 0.53   qualityCode: C
Method: methodID: smi:gov.usgs/focalmec/HASH_1.2
./hypo.1786211879249.mech.hash.mechanism.jpg

Event ID: smi:alomax.net_BETA/author/ee/event/1786211879249
Event info last updated: 2026.08.08-18:56:02 UTC
Event first association/location: 2026.08.08-18:03:01 UTC
Software: Early-est 1.2.10 (2024.02.23)
Agency: alomax.net_BETA