The Trans-Alboran Shear Zone is one of the most seismically active areas
in the westernmost Mediterranean, where a wide variety of tectonic
domains have developed within the context of oblique convergence between
Eurasia and Africa plates. In this region, earthquakes occur close to
seismogenic structures, some of them large enough to cause damaging
events. In addition, the diversity of tectonic domains implies a lateral
variation of seismic wave propagation, which could affect the hypocenter
reliability if not addressed during the location procedure. In this
work, we present mTAB3D, a new 3D P-wave velocity model that accounts
for the lateral heterogeneity of our study area. To test this model, we
used arrival times from the Spanish Seismic Network catalog and
performed two non-linear absolute location inversions: the first
comprises all the seismicity detected during 2018-2022 in the Eastern
Betics Shear Zone; the second one consists of the earthquakes recorded
during the Al-Hoceima seismic sequence (2016). We compare our results
against hypocenters computed with a 1D velocity model of the region
(mIGN1D) and observe that mTAB3D achieves better clustering near active
structures and lower epicentral uncertainties. Moreover, hypocenters
obtained with mTAB3D show notable reliability even in scenarios of a low
azimuthal gap, such as the 2016 Al-Hoceima sequence. The new catalogs
computed with our model help us to infer possible genetic relations
between seismicity and source faults within our study area and can be
used as an additional tool when looking into prior seismic sequences.