Early-est:     Santa Cruz Islands Region    2026.03.31-21:56:34.49    q:B      mb:4.9*    Mwp:-    Mwpd:-    Td*T50Ex:0.2     fmamp_polarity:./hypo.1774994195623.mech.fmamp_polarity.thumb.jpg     fmamp_polarity_waveform:./hypo.1774994195623.mech.fmamp_polarity_waveform.thumb.jpg     hash:./hypo.1774994195623.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* [47]    Mwp: - [0]    Mwpd: - [0]
Region: Santa Cruz Islands Region
Origin Time: 2026.03.31-21:56:34.49 UTC
Hypocenter: lat: -12.75°  lon: 169.36°  [+/-19km]    depth: 643km  [+/-25km]
Location Quality: qualityCode:  B     stdErr: 1.1s   assocPhases: 113   usedPhases: 94
minDist: 9.2°   maxDist: 161.6°   AzGap: 39°   2ndAzGap: 54°   atten: -1.53 [+/-0.20]
Location Uncertainty: 68%ConfEllipse:   minHorUnc: 16km   maxHorUnc: 19km   azMaxHorUnc: 17°
68%ConfEllipsoid:   semiMajorAxisLength: 29km   majorAxisAzimuth: 185°   majorAxisPlunge: 50°   semiIntermediateAxisLength: 21km   intermediateAxisAzimuth: 81°   intermediateAxisPlunge: 11°   semiMinorAxisLength: 17km
Tsunamigeneic Assesment:
Discriminants: Prob Underwater: >99%
T50Ex: 0.3 [31]    Td: 0.5s [4]    Td*T50Ex: 0.2 [4]    To: 1.1s [28]
Closest plate boundaries:
   New Hebrides - Pacific [oceanic spreading ridge]: distance: ~100km
Subduction geometry: none or not available
Decision table (TEST!):
Event type: Subduction Zone Other Thrust/Normal Strike-slip
Compatible close plate boundary?:
 no
 no
 no
Prob underwater:
 >99%
 >99%
 >99%
Td*T50Ex:
   0.2
   0.2
   0.2
Td*To:
     0.6
     0.6
     0.6
Mwp magnitude:
       -
       -
       -
Hypocenter depth:
       643km
       643km
       643km
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.1774994195623.map.jpg

First-motion Focal Mechanism (FMAMP_POLARITY):    (Warning: Unreliable solution, qualityCode=C)
Nodal Plane 1: strike: 206°   dip: 20°   rake: -157°
Nodal Plane 2: strike: 94°   dip: 82°   rake: -71°
Quality: azimuthalGap: -1°   stationPolarityCount: 49   misfitWeightCount: 15.1   misfit: 0.19   stationDistributionRatio: 0.53   meanDistP: 31.3   meanDistT: 50.1   qualityCode: C
Method: methodID: smi:net.alomax/focalmec/fmamp_0.0.5X_2016.06.14/_polarity
./hypo.1774994195623.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.1774994195623.mech.fmamp_polarity_waveform.mechanism.jpg
First-motion Focal Mechanism (HASH):    (Warning: Unreliable solution, qualityCode=C)
Nodal Plane 1: strike: 164°   dip: 29°   rake: -177°
Nodal Plane 2: strike: 71°   dip: 89°   rake: -61°
Quality: azimuthalGap: 57°   stationPolarityCount: 49   misfit: 0.41   stationDistributionRatio: 0.68   rmsAngDiffAccPref: 31.73   fracAcc30degPref: 0.82   qualityCode: C
Method: methodID: smi:gov.usgs/focalmec/HASH_1.2
./hypo.1774994195623.mech.hash.mechanism.jpg

Event ID: smi:alomax.net_BETA/author/ee/event/1774994195623
Event info last updated: 2026.03.31-22:55:02 UTC
Event first association/location: 2026.03.31-22:02:01 UTC
Software: Early-est 1.2.10 (2024.02.23)
Agency: alomax.net_BETA