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Seismic Metadata v.1

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General Information

Data Type

2D Multichannel Seismic

Data Acquisition System

Bolt Airgun and Sentry Solid Streamer

Contributor

U.S. Geological Survey

Dates

Started on Aug. 6, 2011, and ended on Sept. 1, 2011.

Number of Tracklines

18

Distance Shot

3,773 km

Description

In 2011, the U.S. Geological Survey (USGS) conducted a 2D MCS survey in support of U.S. extended continental shelf (ECS) assessments in the Bering Sea. The survey was conducted with the R/V Marcus G. Langseth, a geophysical research vessel owned by the National Science Foundation and operated by Lamont-Doherty Earth Observatory of Columbia University.

Purpose

This field survey were designed to determine sediment thickness and acoustic velocity in support of extended continental shelf maritime zone definition, conducted on behalf of the interagency U.S. Extended Continental Shelf Project, and are being released without restriction or warranty.

Other Survey Identifiers

MGL1111 was used by Lamont-Doherty Earth Observatory.

Geographic Features

Bering Sea

Dataset Information

Processed Methods

Seismic Reflection

Processed Data Classes

Migration, Stack

Data File Formats

SEG-Y

Embedded Navigation

Yes

Data Class

Processed

Seismic Data Provenances

Digitally Acquired Digital SEG

Data Media

Online

Data Quality

The quality of the MCS data was excellent on the cruise. No major problems occurred with the seismic system. The airguns were powered down 6 times during L-11-11-BS but these power-downs introduced no significant data gaps. Most power-downs lasted 30 minutes or less. In these cases, with an 8 km streamer, the fold was reduced but no gap in the profile section resulted. During the survey, some variability in gun array volume and streamer depth occurred due to weather and maintenance requirements. This is documented in the observer logs for each acquisition line.

Processing

Field data were recorded in demultiplexed SEG-D format. Upon completion of an MCS profile line, SEG-D data files (one per shot) were posted to the ship’s server. These were concatenated into a single SEG-D file and imported to Paradigm’s Focus software for processing. Products of shipboard processing included raw shot gathers, CDP gathers processed through gapped predictive deconvolution, preliminary unmigrated stacked sections, post-stack FK-migrated sections, and stacking velocity fields. All MCS processing was reviewed and finalized post-cruise.

Navigation Information

Datum

World Geodetic System 1984 (WGS84)

Location

Tracklines 18 total

Name Length (km) First SP Last SP First CDP Last CDP
MGL1111-01 246 719 3,505 663 23,566
MGL1111-01A 182 1,007 3,006 653 17,270
MGL1111-02 187 1,009 3,049 650 17,598
MGL1111-03 263 690 3,562 679 24,278
MGL1111-04 138 1,090 2,589 663 13,278
MGL1111-05 407 844 5,295 663 36,894
MGL1111-05T 28 1,054 1,350 663 3,654
MGL1111-07 580 926 7,098 650 50,654
MGL1111-08 336 1,469 4,988 690 29,470
MGL1111-09 273 1,036 3,965 650 24,710
MGL1111-09A 148 1,012 2,617 650 14,118
MGL1111-10 144 906 2,379 663 13,070
MGL1111-11 250 920 3,626 650 22,926
MGL1111-11T 78 997 1,809 663 7,782
MGL1111-12 218 971 3,313 650 20,014
MGL1111-12T 34 1,011 1,377 650 4,206
MGL1111-13 177 1,089 2,985 650 16,446
MGL1111-14 85 909 1,875 663 9,014

Acquisition Parameters

Name Value
Field Activity Identifiers L-11-11-BS, MGL1111
Vessels R/V Marcus G. Langseth
Navigation System C-Nav 3050
Horizontal Datum World Geodetic System 1984
Recording System Sercel Syntrak 960
Antenna to source 223 meters
Source to near channel 176 meters
Near channel number 636
Number of channels recorded 636
Number of cables 1
Number of channels each cable 636
Source to far channel 13 meters
Cable length 8,000 meters
Cable receiver depth 9 meters
Cable receiver depth recorded Yes
Number of sources 36
Source array separation 8 meters
Source Depth 9 meters
Source volume 6,600 cubic inches
Source pressure 138 bars
Shot interval 50 meters
Sample interval 2,000 microseconds
Record length 16 seconds
Nominal fold 80
Recording delay No
Compass birds Yes
Tailbuoy positioning Yes
Flip-flop shooting No