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An updated version of the Mentone, Texas cluster (mentone5) was uploaded, adding more recent events.

This version of the Mentone cluster replaces an earlier result
(mentone3) posted in GCCEL. This version is quite different in the
included events, which are required to have been observed to at least 10
degrees epicentral distance. The Mentone cluster is named after the town
of Mentone in west Texas, U.S.A. The cluster was originally motivated by
the occurrence of a 5.0 Mw earthquake on March 26, 2020 and the sequence
includes several other eevents near magnitude 5: 5.3 Mw on November 16,
2022, 5.2 Mw event on November 8, 2023 and 4.9 Mw as recently as
February 15, 2025. The region is a major producer of gas and oil and the
bulk of the seismicity is likely induced by excessive waste water
injection, as in Oklahoma and elsewhere. The earliest events in the
sequence are not included, due to lesser quality datasets. The
distribution of seismograph stations in the source region is now quite
dense; this version of the cluster was limited to events since January
2021. Azimuthal coverage and near-source data are exceptionally good for
all events. The entire cluster has been relocated with free depth but
the focal depths of a few events needed manual adjustment to better fit
the near-source data, so the final runs were done with fixed depth (at
the free-depth solution in most cases).

The Jamaica cluster is named for the island nation of Jamaica in the
Caribbean Sea. The arrival time data required a crustal model with quite
shallow Moho, about 20 km, and a single layer crust fits the data well.
However, the overlap between direct crustal phases and Moho-refracted
phases makes phase identification (and depth control) more challenging
than usual. The cluster contains two moderate-sized events, a 5.6 Ms
event on November 12, 1988 and a 5.5 mb event on January 13, 1993. Over
half the events are recorded teleseismically, but smaller events have
been retained to improve the statistical power for location calibration.
All events have depth control, mainly from near-source and
local-distance readings, but several are constrained by teleseismic
depth phases.

The Thera cluster is named for the volcanic island Thera (also known as
Santorini), the southernmost member of the Cyclades island group in the
Aegean Sea. The cluster is dominated by an earthquake sequence that
began in early February, 2025, 20-40 km northeast of Thera. The sequence
has swarmlike characteristics but it is, as yet, unclear if the activity
is volcanic or tectonic in nature. The cluster includes the 7.7 Mw
tsunamigenic earthquake of July 9, 1956 and 3 of its aftershocks. The
mainshock is located ~10 km southeast of the southern end of the ongoing
2025 swarm, midway between the southern end of the Santorini-Amorgos
Fault and the Anafi-Astypalaea Fault. Some of the earlier members of the
cluster are grouped near an apparent submarine volcanic feature midway
between the Thera island and the 2025 sequence. The 2025 activity
includes several events with magnitude 5+, up to M5.3. Most events in
the cluster are observed to teleseismic distances, but some smaller
events prior to the 2025 sequence are retained because they provide
important azimuthal control for the location calibration. All events
except the 1956 events and a single small event in 1968, which are held
at 10 km focal depth, have depth control from near-source or
local-distance readings.

The Prince William Sound cluster is named for the sound on the eastern
side of the Kenai Peninsula of southern Alaska, but it extends well
north of the sound, through the Chugach Mountains and south into the
Gulf of Alaska. The epicenter of the 9.2 Mw “Good Friday” earthquake on
March 28 (March 27 local time), 1964 is on the northern shore of the
sound. The cluster includes the mainshock and most of the significant
aftershocks of the eastern part of the 1964 sequence, east of ~148°W.
The full aftershock zone extends westward to ~154°W. Until the mid-1980s
there were very few seismograph stations in the area; the nearest
station to the 1964 mainshock was station COL at a distance of more than
300 km. Since the 1990s the density of stations has increased
dramatically. Selection of earthquakes for the cluster reflected the
time-dependence in station density. For all dates, events were only
selected if they had a minimum of 30 arrival time observations in the
ISC Bulletin, but for events after 1989 a minimum magnitude of 3.5 was
also imposed to keep the number of events within a manageable limit.
Events were only retained if some form of depth constraint was
available. For events prior to late 1966 this was almost exclusively
from teleseismic depth phases. For subsequent events the preferred
source of depth constraint for most events is near-source and
local-distance readings but teleseismic depth phases are available for
many of the more recent events and they were analyzed for validation.
Approximately 1/3 of the events were observed only to regional
distances; they were retained partly to provide stronger statistical
power for the location calibration, and also because of their
significance for seismotectonic investigations. In addition to
containing more earthquakes (596) than any GCCEL cluster to date, the
Prince William Sound cluster is one of the largest in geographical
terms, approximately 180 x 280 km. Moreover it extends over the
transition from inland Alaska, through the Prince William Sound, to the
continental shelf. The use of a single crustal model for the entire
region is certainly optimistic and it is likely that epicenters near the
perimeter are subject to greater uncertainty than the formal error
estimate.

The Piritu cluster is named for a town in the state of Falcón, in
northwestern Venezuela (there are several other towns named Piritu in
other states). It contains one magnitude 6.0 Ms event, the Boca del
Tocuyo earthquake on April 30, 1989, and several events with magnitudes
5.0-5.9. Station distribution for direct calibration is good, but it was
necessary to retain many smaller events that are observed only to
near-regional distances to obtain good statistical power. All events
have depth control, mainly from near-source and local-distance readings,
but earlier, larger events are often constrained by teleseismic depth
phases.

A new calibrated cluster in the eastern part of the Republic of Tuva, in southern Siberia, has been uploaded.

A new version of the Shushtar cluster (shushtar10.28) in the central Zagros Mountains of Iran replaces the former shushtar8.211 cluster. This version contains almost twice as many events (378 vs 200), including a recent 5.4 Mw event on December 5, 2024.

The former Fin-Tiab calibrated cluster (fintiab7) in southern Iran has been replaced by a new version (fintiab11) that has many more events (505 vs. 117).

New calibrated cluster posted to GCCEL:

The Dezhgan cluster is named for the village of Dezhgan in Hormozgan
Province in southern Iran. The cluster includes seismicity at Qeshm
Island in the Strait of Hormuz. The cluster contains many earthquakes
with magnitudes in the range 5.0-5.9, and three larger events, 6.0 mb on
September 10, 2008 (at Qeshm Island) and 6.0 and 6.3 mb on July 1, 2022.
In order to obtain adequate azimuthal coverage for direct calibration it
was necessary to extend the distance limit used for estimating the
hypocentroid to 1.2°, to pick up readings from seismograph stations to
the south, across the Strait of Hormuz, in the UAE. In the distance
range 1.0-1.2° Pn and Sn arrivals are often found following close to the
arrival times of direct crustal phases Pg and Sg. This required careful
inspection of residuals to avoid biasing depth estimates. The data set
includes arrival times from temporary network stations that were
operated on Qeshm Island by Yamini Fard and colleagues from the IIEES,
as well as observations of S-P reported from strong motion stations very
near epicenters on Qeshm Island by Reza Ghods from IASBS. These data
help constrain focal depths and also helped guard against location bias
from unmodeled lateral heterogeneity, which is likely rather strong in
this area.

Latest upload for GCCEL:

The Kurikoma cluster is named for Mt. Kurikoma, a stratovolcano in
northern Honshu, Japan. Much of the seismicity in the region is thought
to be related to magmatic activity. The cluster includes 5 earthquakes
of magnitude 6.0-7.0, and most of the smaller events appear to have
occurred as aftershocks or swarms related to these larger events.
Station coverage for location calibration and depth control is
excellent. All events have depth control from near-source or
local-distance observations. All events are recorded at teleseismic
distances.