NVT errors estimates
We accepted formal errors of NVT localizations obtained from HYPOINVERCE-2000 [Klein, 2007].
These errors estimated as: "The vertical error ERZ and horizontal error ERH are simplified
errors derived from the lengths and directions of the principal axes of the error ellipsoid.
Each of the three principal axes (whose lengths are the standard errors) are projected onto a
vertical line through the hypocenter, and the largest value is ERZ. ERH is simply the length
of the longest of the principal axes when viewed from above and projected onto a horizontal plane.
... error ellipse scales with the estimated error RDERR (represents the aggregate of all
un-modeled timing errors) and the earthquake’s RMS."
Figure S5 presents NVT events locations and corresponding depth errors (ERZ) projected onto the
vertical plane parallel to the trench strike. Normally ERZs are ? 10 km for the NVT hypocenters
located below the MASE network. ERZs increase noticeably for the NVT located sideways on to the
MASE profile. Even the NVT depths are rather uncertain the most of reliably located NVT bursts
tend to occur in the continental crust.
Horizontal errors (ERH) are less for the NVT epicenters located eastward from the MASE profile
(Figure S6) than for the tremor events occurred to the west of it. This asymmetry is clearly
related to the shape of the seismic stations chain. It is concave to the east at latitude ~18 °N
where the main cluster of NVT is detected. The most of the NVT locations have ERH<20 km.
Reference
Klein, F.W. (2007), User’s Guide to HYPOINVERSE-2000, a FORTRAN Program to Solve for Earthquake
Locations and Magnitudes, version 1.1, USGS Open File Report 02-171 revised.