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The Ahel cluster is named for the village of Ahel in Fars Province, Iran. This cluster consists of 184 events including the October 31, 1956 Gowdeh earthquake (Magnitude 6.6) and fourteen more older events prior to 1980. Calibration is greatly aided by data from a temporary network deployed by Farzam Yamini-Fard (IIEES). A.R. Ghods (IASBS) repicked many of the arrival times from Iranian networks, including S-P data from the INSM network of accelerometers (BHRC). Focal depths of 23 events are constrained with near-source data, 15 are set by local-distance data, and reminder are fixed to a cluster default of 12 km. Further information about this cluster is contained in: Karasözen et al. (in preparation), Seismotectonics...
The Turt cluster is named for a small settlement on the northeastern shore of Lake Khovsgol in northern Mongolia. The cluster crosses the border with Russia, into Buryatia. The cluster was formed around a 6.7 Mw earthquake on January 11, 2021. This event was followed by a large number of aftershocks which could have been included in the cluster but the coverage from local stations for these events was unbalanced and the location calibration tended to become unstable when a large number of them were included. Most of them were only recorded at regional distances. Several of the largest aftershocks are included. It was difficult to obtain adequate azimuthal coverage for this cluster but the final selection of events...
The Potenza cluster is named for the city of Potenza in the region of Basilicata in southern Italy. It includes the Irpinia earthquake (Ms 6.8) on November 23, 1980, and includes a number of moderate-sized events in recent years. The number of seismic stations in the source region increased markedly in 1999 and again in 2010, making direct calibration very easy. The velocity structure was refined with a subset of recent events for which free-depth relocations could be done. All events have depth constraint from near-source or local distance readings, or for a couple events, teleseismic depth phases. ...
The Kaki cluster is based on the Mw 6.2 mainshock on April 9, 2013, a few tens of km southeast of Bushehr in southern Iran. It's named after a village near the epicenter. The 2013 sequence, including one foreshock and aftershocks through the end of the year, comprises over half of the cluster. Arrival time readings from a temporary seismic network deployed by F. Yamini-Fard (IIEES) to monitor aftershocks are of critical importance to calibrating this cluster. The calibration of this cluster is done by both with direct and indirect technique; near-distance readings up to 0.4 degrees are used for the direct calibration and 18 well calibrated events located by the temporary seismic networks are used for indirect calibration....
The Kobe cluster is named for the city of Kobe, Japan. The cluster is based on the Ms 6.9 earthquake on January 16, 1995 and its aftershocks but it includes more recent events as well. Fitting the pattern of arrivals at local distances required an unusually low crustal P velocity. Number of events: 60 Calibration type: direct calibration using data to 1.0 degrees; hypocentroid calibration level = 0.6 km Epicentral calibration range: 1 - 1 km Date range: 19950116 - 20140805 Latitude range: 34.107 - 35.158 Longitude range: 134.672 - 135.802 Depth range: 14.0 - 22.0 Magnitude range: 3.5...
The Samaria cluster is named for the old community of Samaria, Idaho and the Samaria Mountains in southeastern Idaho. The cluster straddles the border with Utah. It contains one large earthquake, an M6.1 event on March 28, 1975, but none of the other events exceeds 4.6 in magnitude. The M6.1 (USGS) earthquake is often referred to as the Pocatello Valley earthquake. About half of the events are from the 1970s and the quality and quantity of arrival time data are poorer than for modern events; in particular they have few S readings. Focal depths are established by free depth relocation but they are rather unstable and the uncertainties are larger than usual. Depths span a large range, roughly from zero to 20 km,...
The Zahle cluster is named for the city of Zahle, Lebanon, but it covers most of the country and includes some offshore events as well. Most events are small and there are few arrival time data beyond ~30° epicentral distance. The distribution of stations is quite good and the calibration analysis is robust. All events have depth constraint. Depths range through most of the crust. Number of events: 69 Calibration type: direct calibration using data to 0.7 degrees; hypocentroid calibration level = 1.0 km Epicentral calibration range: 1 - 3 km Date range: 19950423 - 20180107 Latitude range: ...
The Baskale cluster is named for the city of Baskale in southeastern Turkey, near the border with Iran. The cluster is a bit small in number and includes only one event larger than magnitude 5 (5.4 mb on January 25, 2005), but the location calibration is quite good. All events are recorded to teleseismic distances and all have depth constraint from near-source or local-distance readings. Number of events: 27 Calibration type: direct calibration using data to 1.0 degrees; hypocentroid calibration level = 1.5 km Epicentral calibration range: 2 - 3 km Date range: 20050125 - 20201220 Latitude...
The Hualien cluster is named for a city on the east coast of Taiwan. The region has been very seismically active at magnitudes up to low magnitude 6 in recent decades but on April 2, 2024 it experienced a 7.4 Mw earthquake. The cluster includes the mainshock of the April 2024 sequence and 15 of the larger aftershocks. Local and regional data from the very dense Taiwan network is available for events up to June 2022 but for the more recent events only a handful of the Taiwanese stations were available at the time of this analysis. Recent events all have large datasets of far-regional and teleseismic readings, however, and are well-constrained in the cluster. Only three events have magnitude less than 5.0. All events...
The NEIC global earthquake bulletin is called the Preliminary Determination of Epicenters or PDE, and is one of many discrete products in the ANSS Comprehensive Catalog (ComCat). We use the word "Preliminary" for our final bulletin because the Bulletin of the International Seismological Centre is considered to be the final global archive of parametric earthquake data, in other words phase arrival (“pick”) times and amplitudes.
Types: Citation;
Tags: ANSS,
Advanced National Seismic System,
ComCat,
Comprehensive Earthquake Catalog,
Earth,
The Cerkes cluster is named for the town of Cerkes in north central Turkey. The seismicity in this region is scattered. There are no events in the cluster as large as M5.0. All events are recorded teleseismically, however, and all have depth control from near-source or local-distance readings. The network coverage is excellent for direct calibration. Number of events: 52 Calibration type: direct calibration using data to 1.0 degrees; hypocentroid calibration level = 0.7 km Epicentral calibration range: 1 - 2 km Date range: 19990317 - 20210110 Latitude range: 39.978 - 41.841 Longitude range:...
The Khutia cluster is named for a village in Abkhazia, a break-away province in western Georgia in the western Caucasus Mountains. Most of the cluster is in Abkhazia, but one dense subcluster of events is off-shore in the Black Sea. The cluster contains a 6.5 Ms event on July 16, 1963 and five earthquakes of magnitude 5.0-5.6 so there is a good sample of teleseismic data. Station distribution for direct calibration is not ideal and a robust result is only obtained by including a fairly large geographic region, using many observations around 1° epicentral distance, and including many earthquakes that are mainly observed at regional distances. All events have depth control, mainly from near-source and local distance...
The Toyama cluster is named for Toyama Prefecture on the northwest coast of Honshu, Japan. It is based on a 7.5 Mw earthquake on January 1, 2024. The cluster includes a foreshock and 32 aftershocks of the first 36 hours. The area has been seismically active for many years and the cluster includes many earlier earthquakes that provide the data coverage necessary for location calibration. Fluid flow driven by magmatic activity has been identified as a likely cause of seismicity in the area by Keisuke Yoshida and colleagues. Nearly all events in the cluster are observed to teleseismic distances. Most events have depth control from near-source and local-distance arrivals, but a few are set to the default depth of 15.0...
Each of the downloadable files below contains spectral response accelerations at 22 periods on a grid of latitudes and longitudes that cover this geographic region. See the parent item for how Risk-Targeted Maximum Considered Earthquake (MCER) spectral response accelerations are derived from the data in these files.
For background, please see the Parent Item. The Maximum Considered Earthquake Geometric Mean (MCEG) peak ground acceleration (PGA) values of the 2009 NEHRP Recommended Seismic Provisions and the 2010 ASCE/SEI 7 Standard are calculated from the data in the downloadable files below, via the following equations: PGA = min[ PGAUH , max( PGAD84th , 0.6 ) ] for the 2009 NEHRP Recommended Seismic Provisions; PGA = min[ PGAUH , max( PGAD84th , 0.5 ) ] for the 2010 ASCE/SEI 7 Standard; where PGAUH = uniform-hazard peak ground acceleration; PGAD84th = 84th-percentile peak ground acceleration; and 0.6 or 0.5 = deterministic lower limit peak ground acceleration. These peak ground...
Categories: Data
The Newdelhi cluster is named for the city of New Delhi, India. Most events in the region are small; a 5.0 mb event is the largest. Most events in the cluster are observed to teleseismic distances. All events have depth control from near-source and local-distance readings, and in two cases, teleseismic depth phases. For many events the number of readings is minimal, which leads to some instability, depending on which readings are considered outliers. Number of events: 48 Calibration type: direct calibration using data to 1.0 degrees; hypocentroid calibration level = 0.8 km Epicentral calibration...
The Shimian cluster is named for Shimian County in Sichuan Province, China. The cluster is based on a 6.6 Mw earthquake on September 5, 2022, and includes a 6.0 Ms event, on January 15, 1975. Location calibration of this cluster depends completely on data from the provincial seismograph networks in the area that was collected by Sun Ruomei. In order to include enough events (with depth control) to obtain good azimuthal coverage and enough arrival time data at local distances for robust statistics, the area of the cluster is larger than usual, over 200 km across. All events are recorded to teleseismic distances and all have depth control, although it is a bit weak in some cases. It appears that seismicity in this...
The Deta cluster is named for the town of Deta, Timis County, in southwest Romania. The cluster also includes some earthquakes in northern Serbia. The seismicity is dominated by a sequence of three M5 events in 1991, the largest events in the cluster. The distribution of seismic stations is quite good for location calibration and about half the events have near-source observations to constrain depth. Depth control for the rest is provided by local-distance observations. Only 10 events have teleseismic observations. Most other events have observations to at least 400 km. Number of events: 70 Calibration...
This is the main folder for the NEIC PDE archives (basically the NEIC catalog out of Hydra rather than a merged view out of ComCat). These files are in ISF format. Data are organized such that there is one folder per year. Within each year folder, the file names for the NEIC catalogs use the convention YYYYWW_cat.isf where: YYYY is the year WW is the number of the week within the year
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