MLOC Data for GCCEL

MLOC Data for GCCEL

This page is an index to the original mloc folders used in developing calibrated hypocenters for clusters of earthquakes for the GCCEL project. These files are provided for researchers who are already experienced in the use of mloc and wish to investigate the calibration of certain clusters or specific events more closely or analyze a cluster with a revised set of events, additional data or different assumptions, and for those who wish to learn to use mloc to conduct calibrated location studies. Researchers who are primarily interested in using the groomed datasets of arrival time data from calibrated hypocenters will be best served by the presentation of the GCCEL data set at the USGS ScienceBase website. That said, each cluster package served here also contains the data files (~_gccel.dat and ~_plots.pdf, in a folder named ~_gccel) that are collected on the official GCCEL website.

Every cluster posted on the official GCCEL website is also posted here. There is sometimes several days difference between the time that a new cluster appears in each location. In a few cases, the names of clusters are different in GCCEL, or they are listed under a different geographical heading.

Each folder is compressed in a ~.zip file. The folders contain all data files needed to relocate the cluster with mloc, including the command file used to generate the output that is posted in the GCCEL data release at the USGS. The source code for mloc is posted elsewhere on this website, along with instructions on compiling the code and setting up a functional mloc relocation environment, all necessary supporting data files and a User’s Manual. Using these resources it should be possible to duplicate all results posted in GCCEL.

There is one caveat: Each run of mloc uses certain output data from the previous run to set starting location parameters and certain statistical parameters that change slightly from run to run. Therefore, in order to reproduce the output of a cluster posted in GCCEL, it would be necessary to have access to some output files of the previous run. Because of the way the files are stored it would have been a substantial amount of extra work to include those files in the posted archives. A run of mloc started from the data files of the run posted in GCCEL will not, in general, be identical to the posted output. The differences will be minor (relative to the uncertainties) in most cases, but could occasionally be significant. If you wish to carry out an exact comparison, contact Eric Bergman.

Supplemental station files

In some cases, an mloc command file may reference one or more supplemental station files outside the cluster folder. The ~.stn file created by each run of mloc includes a section in which all stations from such external files are listed in one of the standard formats (type 3) used by mloc for station coordinate data, making it easy to create a single supplemental station file for the cluster that may be referenced by the sstn command in the command file.

Event Data Files

In most folders the individual event data files are contained in a compressed folder named “Archive”. They need to be moved up a level, into the main cluster folder with the command file. In most cases there will be data files for events that were not used in the final calibrated cluster. The reasons why an event was not used vary. In some cases there were too many candidate events and events were dropped simply to keep the size of the cluster at a practical level. In other cases the event could not be relocated with sufficient confidence. Sometimes an event is judged to be too far away from the main cluster. There is sometimes a “disconnect” in the station coverage between older events and the more recent ones that tend to dominate the calibration process; in those cases we have to prefer the more recent events and drop the older ones, even though they are sometimes the largest events in the source region. In some cases events are dropped because there was poor (or no) control on focal depth. For GCCEL we usually require at least a modest level of depth constraint from near-source or local-distance readings, teleseismic depth phases or waveform analysis. It is easy to set a default depth for events in a cluster and for some purposes this would be a desirable approach, in order to have a fuller representation of the distribution of seismicity in the source region. Experiment is the only way to determine if any individual event could be successfully added to the cluster.

Version Control

Clusters are sometimes revisited and updated. The ~.summary file (a standard element of the output of each run of mloc) contains information on the date the analysis was done, the author of the analysis and the version of mloc that was used. Each entry in the index below carries the date on which it was uploaded, which is normally no more than a few days after the date of the relocation analysis. If a GCCEL cluster is updated after being posted here, the new date and a note about the replacement will appear in the entry.

Current Status

As of November 10, 2024 the GCCEL database contains 362 calibrated clusters. The number of clusters sometimes goes down when several older clusters are revisited and combined into a single cluster. A compressed KML file of the hypocentral information in the database on this date can be downloaded from this link: gccel.kmz (1.0 MB).

Recent Additions (since January 1, 2024)

Organization

The clusters are organized by country or prominent geographic designation.

Albania

  • Tirana (2019/12/3, 11.4 MB)
  • Vlore (2022/5/29, 6.3 MB)

Algeria

Argentina

Armenia

Australia

Austria

Azerbaijan

Azores Islands

  • Pico (2018/2/21, 2.2 MB)

Bosnia & Herzegovina

Bulgaria

Canada

Chile

China

Colombia

Costa Rica

Croatia

Cyprus

Djibouti

Ecuador

El Salvador

French Polynesia

Georgia

Germany

Greece

Guatemala

Gulf of Aqaba

Haiti

Iceland

India

Indonesia

Iran

Israel

Italy

Japan

Kazakhstan

Kyrgyzstan

Laos

Lebanon

  • Zahle (2019/12/3, 2.3 MB)

Leeward Islands

Malawi

Marshall Islands

Mexico

Mongolia

  • Turt (2021/7/3, 3.3 MB)

Morocco

Mozambique

Myanmar

Nepal

New Zealand

Nicaraugua

North Korea

North Macedonia

Norway

Oceanic

Pakistan

Panama

Papua New Guinea

  • Lae (2018/6/26, 3.7 MB)

Philippines

Portugal

Romania

Russia

Serbia

South Africa

South Korea

Spain

Taiwan

Tajikistan

Thailand

Turkey

United States

Uzbekistan

Venezuela