Coastal and Marine Geology Metadata and Data

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Seismic

See also, National Archive of Marine Seismic Surveys (NAMSS).

Seismic information covers a wide range of information including:

General Type Description Equipment
conventional multichannel seismic reflection profile data typically acquired with a large multiple airgun array; 10 to 100 Hz spectral content (2 ms sample) and 8 to 20 sec record length; CDP interval typically 25 to 100 meters; 12 to 48 fold. 24 Channel
48 Channel
96 Channel
high-resolution multichannel seismic reflection profile data typically acquired with a single small airgun, GI gun or watergun; 50 to 500 Hz spectral content (0.5 ms sample) and 1 to 2 sec record length; CDP interval typically 3 to 5 meters; 6 to 24 fold. GI Gun
Minisparker
Small Airgun
Watergun
conventional single channel seismic reflection profile data typically acquired with a large (10 to 20 kJ large airgun or multiple airgun array; 10 to 100 Hz spectral content and 8 to 10 sec record length; shot interval typically 25 to 50 m; no fold; prior to 1990, rarely digitally recorded. Airgun
Sparker
high resolution single channel seismic reflection profile data typically acquired with a small sparker (2 kJ), small airgun, GI gun, or watergun; often includes two-channel data, which are independent receivers; spectral content 100 to 1000 Hz (0.25 to 0.5 ms sample); shot interval 3 to 10 meters. Minisparker
Watergun
very high resolution single channel seismic reflection profile data typically acquired with any of a wide variety of electromechanical transducers, broadly classed as wide-band (boomer, geopulse, seistec) or narrow-band (chirp); spectral content 1000 to 10000 Hz (sample rate 8 to 32 kHz); shot (or ping) frequency 0.125 to 0.5 sec (0.2 to 1 meter). 3.5 kHz
12 kHz
Datasonics CAP600
Datasonics SIS1000
Chirp
Delnorte
Geopulse
Huntec
Boomer
Bubblepulser
Seistec
Uniboom
wide angle reflection/refraction seismic reflection/refraction profile data typically acquired with a large airgun source to offsets of 20 to 100 km. Ocean Bottom Hydrophone
Ocean Bottom Seismometer
Sonobuoy

Seismic data are collected by "shooting" a source at either:

Each "shot" is an actual sound burst in the water.

Time associated with shots and with navigation are used for plotting on a map.

Shots can have other names like:

"CDPs" (Common Depth Point), sometimes called CMP (Common Mid-Point)

But, how is the latitude and longitude of each CDP location, when the navigation is for the ship at a certain time and no unique time is associated with a CDP?
Illustration of multiple raypaths

On maps:

Seismic information:

scattered < Activity-ID >.4## files containing time sequential information along ship tracks.
metadata information about seismic analog paper rolls, inventory of gear, operation of gear, magnetic tapes, and paper printer listings

Seismic data file names:

<Activity-ID>.40# Raw seismic shot points
<Activity-ID>.42# Edited seismic shot points

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Page Last Modified: Mon Nov 4 03:37:33 PST 2013