Category: Uncategorized

The Ziarat cluster is named for the city of Ziarat in northeast
Baluchistan Province, Pakistan. The cluster includes 7.0 Ms and 7.4 Ms
earthquakes in August 1931 and the 7.1 Mw event on February 27, 1997.
The cluster is motivated by a pair of 6.4 Mw earthquakes that occurred
on October 28 and 29, 2008 and that provide a basis for location
calibration. The source region is very poorly instrumented but the 2008
sequence has been studied by several groups using InSAR to try to
unravel what is evidently a very complex faulting pattern, featuring as
many as 5 major faults with conjugate geometry. The location calibration
is done with indirect calibration, fitting the relative locations of the
mainshocks and larger aftershocks to this complex pattern. The InSAR
signal of a more recent Mw 6.0 event (October 6, 2021) helps in
constraining the calibration. Origin time is constrained by Pg and Sg
readings from the seismograph station QUE at Quetta, the only station
within local distance of the cluster. All earthquakes have depth
control, from near-source and local distance readings from QUE and for
many events, teleseismic depth phases. All events are observed at
teleseismic distances.

The distribution package of mloc v13.0.6 (zipped archive ~450 MB) is now posted on the website, as well as an updated version of the Desktop User’s Manual (zipped archive, ~17 MB). This update contains mostly minor bug fixes and tweaks to some of the output files and plots.

The Karaman cluster is named for the city of Karaman in south-central
Turkey. The cluster covers a fairly large area but it is one of modest
seismicity. About a quarter of the earthquakes occur offshore, between
the southern coast of Turkey and Cyprus. The largest event is only 5.2
mb. The cluster is restricted to events observed at teleseismic
distances. Station distribution for location calibration is very good.
All events have depth control from near-source and local-distance
readings.

The Konitsa cluster is named for the town of Konitsa in northwestern
Greece, near the border with Albania. The cluster was motivated by a 5.5
Mw earthquake on March 8, 2026 and includes a 5.6 mb event on October
13, 1969 and several other events greater than magnitude 5.0. All events
are observed to teleseismic distances and all events have depth
constraint, mainly from near-source and local-distance observations. The
depths of several early events are constrained by teleseismic depth
phases. Two events with near-source observations are deep, around 60 km,
but the remainder are at crustal depths between about 5 and 25 km. The
distribution of stations is excellent and location calibration is very
robust.

The Fallon cluster is named for the town of Fallon in western Nevada,
U.S.A. The cluster includes two recent sequences headed by
moderate-sized events, the 5.8 Mw Parker Butte earthquake on December 9,
2024 and a 5.7 Mw event on April 14, 2026 about 18 km north-northwest,
near Silver Springs. The cluster covers a considerably larger area than
these two sequences, mainly to the northeast because this region was the
site of a series of magnitude 6 and 7 earthquakes in 1954 and 1959. The
attempt to include these important earthquakes in the calibrated cluster
was ultimately abandoned due to the poor connectivity with the modern
seismicity. In the 1950s there were very few seismograph stations at
local or near-regional distances and most of them are no longer
operating. With the exception of the two recent moderate-sized events,
most of the remaining events in the cluster are less than magnitude 4
and have few readings beyond regional distances, so the overlap of
observing stations between the older large earthquakes and modern
lower-magnitude seismicity is very scant: around a dozen stations in
common, `even for the largest event, the December 16, 1954 Fairview Peak
earthquake (7.1 Mw). Station distribution for location calibration is
very good. All events have depth control from near-source or
local-distance readings.

The Baetov cluster is named for the city of Baetov in the Naryn region of
Kyrgyzstan. The region is seismically active at lower magnitudes, and
the cluster is dominated by earthquakes observed to near-regional
distances. There is a sufficient number of larger events, up to 5.8 Mw
(January 9, 1997), to provide good teleseismic coverage. Azimuthal
coverage for location calibration is quite good. All events have depth
control, mainly from near-source and local distance readings but a few
events are constrained by teleseismic depth phases.

The Zhaotong cluster is named for the city of Zhaotong in the northeast
corner of Yunnan Province, China. The cluster includes events in
neighboring Guizhou and Sichuan Provinces. The cluster includes one
larger event, a 6.2 Mw earthquake on August 3, 2014. Almost all the
local observations that are used for location calibration are from a
dataset of observations from provincial seismograph networks that was
assembled by Sun Ruomei. The distribution of stations is very good and
the location calibration is very robust. All events have depth
constraint, mainly from near-source and local-distance observations, and
some events are constrained by teleseismic depth phases.

The Fuji cluster is named for Mt. Fuji on the island of Honshu, Japan.
Much of the seismicity is associated with the nearby Izu Peninsula. The
cluster includes the great Kanto earthquake of September 1, 1923 (8.0
Mw). The region was heavily instrumented even in the 1920s and the
location calibration is very robust. All events have depth control from
near-source and local-distance readings, and about half the events also
have teleseismic depth phases in generally good agreement. Most events
are observed at teleseismic distances.

The Parker cluster is named for Parker Butte on the outskirts of
Yerington in western Nevada, U.S.A. The cluster is motivated by the 5.8
Mw Parker Butte earthquake on December 9, 2024, which occurred a short
distance northeast of the butte. About half the events in the cluster
are associated with this mainshock, including several apparent
foreshocks. No other earthquake in the cluster exceeds 4.1 in magnitude
and most events are recorded only to near-regional distances. Despite
that, the seismograph network in this area is quite dense and the
location calibration is very robust. A free depth relocation is possible
and many events are held fixed at those depths for the final runs, but
some events with very near-source observations (less than 5 km
epicentral distance) required manual adjustment to match the closest
observations.

The Samar cluster is named for the island of Samar in the Philippines.
It includes events in the subduction zone under the eastern part of the
island, reaching a depth of ~160 km, and a linear NW-SE-trending belt of
seismicity at crustal depths to the west. The cluster includes three M6
events, on October 26, 1980 (6.3 Mw), February 15, 2003 (6.2 Mw) and
August 18, 2020 (6.6 Mw). A relatively large area had to be included to
obtain adequate azimuthal coverage for location calibration. All
earthquakes have depth control from near-source and local-distance
readings and about half of them also have teleseismic depth phases that
are generally in agreement.