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The former Fin-Tiab calibrated cluster (fintiab7) in southern Iran has been replaced by a new version (fintiab11) that has many more events (505 vs. 117).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

Version 12 of mloc is now being used for new calibrated clusters. Version 11 was meant to be the release of this greatly updated code but it ended up being mainly used for development and testing. The changes in v12 vastly improve memory management and execution time, making it possible to analyze much larger clusters than before. Clusters of 500 events or more are practical on a Mac Mini with M2 chip and only 8 GB of RAM. This version of mloc will be posted soon, when I’ve finished updating the User’s Manual, but if you’re anxious to get started with it, get in touch with me directly.

Since the last update on new clusters in August I’ve posted eight new ones, in China, Iran, Tajikistan, Russia, and Uzbekistan.

Since I last posted about new calibrated clusters for GCCEL in April, I have uploaded 15 new ones, bringing the total number of calibrated clusters to 359. The regions I’ve been working in include the western U.S., Japan and China. You can see them at the “MLOC data for GCCEL” page .

mloc version 11 is a major update to the software that has been in progress since March of this year. I have done a considerable amount of testing and I’ve been using it for recent calibrated clusters uploaded to the GCCEL database. I’m no longer finding (m)any bugs with the way I typically use it, but several other people are using mloc for rather different studies however and they may well uncover a few more bugs that need attention. I expect to declare this version ready for release in the next month or two.

The main advantage of version 11 is the management of memory, which is much more efficient now. As a result the limitation that previously existed on the number of events that can be in a cluster has been lifted. I have made runs with clusters of over 500 events and one of the current users is running clusters approaching 1000 events. Of course, these runs still take a lot of time, and careful analysis of such large clusters is very time-consuming. The other main advantage of version 11 is not evident to the user, but very useful for the developer: placing all subroutines in Fortran modules and getting rid of large named common blocks in include files to handle global variables.

One known issue that I will try to resolve before release of v11 is the annoying discovery that the scripts it produces for plots are in some cases incompatible with GMT v6.5. For the time being, GMT 6.4 or below must be used.