# Accession Number:

## ADA193235

# Title:

## Velocity and Attenuation Profiles in the Monterey Deep-Sea Fan

# Descriptive Note:

## Doctoral thesis

# Corporate Author:

## SCRIPPS INSTITUTION OF OCEANOGRAPHY LA JOLLA CA MARINE PHYSICAL LAB

# Personal Author(s):

# Report Date:

## 1987-12-01

# Pagination or Media Count:

## 101.0

# Abstract:

Data obtained during a refraction experiment is used to estimate velocity and attenuation profiles in an area of thick sediments 2.5 -3 km. A vertical hydrophone array was deployed at mid-depth in 2800 meters of water. Estimates of velocity as a function of depth, and attenuation as a function of frequency and depth are obtained from an analysis of the pressure time series generated by the explosive charges and received at the array. To find the velocity profile, the sediment is modeled as a horizontally layered, laterally homogeneous medium. A least squares solution is found for the velocity gradients in each layer of the model. Velocity as a function of depth is obtained by integrating these gradients. A second method to infer velocity structure using linear programming takes upper and lower bounds on the input data and gives as a solution upper and lower bounds on the velocity profile. All velocity profiles consistent with the data lie within these bounds. Using a similar sediment model, a method of spectral ratios estimates attenuation in the sediment as a function of frequency and depth. Solving for each of the coefficients gives attenuation as a function of depth.

# Descriptors:

- *ACOUSTIC DETECTION
- *OCEAN BOTTOM SOILS
- *SEDIMENTS
- ACOUSTIC ATTENUATION
- ACOUSTIC REFRACTION
- ACOUSTIC VELOCITY
- ANGLE OF ARRIVAL
- ARRAYS
- ATTENUATION
- COEFFICIENTS
- DEEP OCEANS
- ESTIMATES
- EXPLOSIVE CHARGES
- GRADIENTS
- HOMOGENEITY
- HYDROPHONES
- INPUT
- LAYERS
- LEAST SQUARES METHOD
- LINEAR PROGRAMMING
- MODELS
- PRESSURE
- PROFILES
- RATIOS
- SOLUTIONS(GENERAL)
- SPECTRA
- THICKNESS
- TIME SERIES ANALYSIS
- VERTICAL ORIENTATION

# Subject Categories:

- Physical and Dynamic Oceanography
- Acoustic Detection and Detectors