Early-est:     Near East Coast of Honshu, Japan    2026.04.02-00:52:58.36    q:C      mb:4.9*    Mwp:-    Mwpd:-    Td*T50Ex:-     fmamp_polarity:./hypo.1775091172752.mech.fmamp_polarity.thumb.jpg     fmamp_polarity_waveform:./hypo.1775091172752.mech.fmamp_polarity_waveform.thumb.jpg     hash:./hypo.1775091172752.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: 4.9* [36]    Mwp: - [0]    Mwpd: - [0]
Region: Near East Coast of Honshu, Japan
Origin Time: 2026.04.02-00:52:58.36 UTC
Hypocenter: lat: 37.96°  lon: 141.56°  [+/-37km]    depth: 109km  [+/-79km]
Location Quality: qualityCode:  C     stdErr: 1.7s   assocPhases: 56   usedPhases: 44
minDist: 2.6°   maxDist: 151.8°   AzGap: 110°   2ndAzGap: 133°   atten: -0.58 [+/-0.28]
Location Uncertainty: 68%ConfEllipse:   minHorUnc: 30km   maxHorUnc: 37km   azMaxHorUnc: 98°
68%ConfEllipsoid:   semiMajorAxisLength: 81km   majorAxisAzimuth: 249°   majorAxisPlunge: 78°   semiIntermediateAxisLength: 44km   intermediateAxisAzimuth: 107°   intermediateAxisPlunge: 10°   semiMinorAxisLength: 36km
Tsunamigeneic Assesment:
Discriminants: Prob Underwater: >99%
T50Ex: 0.5 [29]    Td: 0.3Xs [1]    Td*T50Ex: - [0]    To: 30.1s [27]
Closest plate boundaries:
   Pacific \ Okhotsk [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 (200km)
 no
 no
Prob underwater:
 >99%
 >99%
 >99%
Td*T50Ex:
   -
   -
   -
Td*To:
     -
     -
     -
Mwp magnitude:
       -
       -
       -
Hypocenter depth:
       109km
       109km
       109km
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.1775091172752.map.jpg

First-motion Focal Mechanism (FMAMP_POLARITY):    (Warning: Unreliable solution, qualityCode=C)
Nodal Plane 1: strike: 73°   dip: 42°   rake: -148°
Nodal Plane 2: strike: 319°   dip: 69°   rake: -52°
Quality: azimuthalGap: -1°   stationPolarityCount: 27   misfitWeightCount: 6.2   misfit: 0.02   stationDistributionRatio: 0.44   meanDistP: 46.7   meanDistT: 41.8   qualityCode: C
Method: methodID: smi:net.alomax/focalmec/fmamp_0.0.5X_2016.06.14/_polarity
./hypo.1775091172752.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.1775091172752.mech.fmamp_polarity_waveform.mechanism.jpg
First-motion Focal Mechanism (HASH):    (Warning: Unreliable solution, qualityCode=C)
Nodal Plane 1: strike: 77°   dip: 46°   rake: -140°
Nodal Plane 2: strike: 317°   dip: 63°   rake: -51°
Quality: azimuthalGap: 98°   stationPolarityCount: 27   misfit: 0.20   stationDistributionRatio: 0.71   rmsAngDiffAccPref: 31.54   fracAcc30degPref: 0.61   qualityCode: C
Method: methodID: smi:gov.usgs/focalmec/HASH_1.2
./hypo.1775091172752.mech.hash.mechanism.jpg

Event ID: smi:alomax.net_BETA/author/ee/event/1775091172752
Event info last updated: 2026.04.02-01:51:00 UTC
Event first association/location: 2026.04.02-01:07:01 UTC
Software: Early-est 1.2.10 (2024.02.23)
Agency: alomax.net_BETA