Graduation Year

2023

Document Type

Thesis

Degree

M.S.

Degree Name

Master of Science (M.S.)

Degree Granting Department

Geosciences

Major Professor

Stephen McNutt, Ph.D.

Committee Member

Jochen Braunmiller, Ph.D.

Committee Member

Rocco Malservisi, Ph.D.

Abstract

The fact that Florida is an earthquake-free region has caused seismologists to pay less attention to it. Few earthquakes in this state mean it is not a usual practice to study the propagation of seismic waves. However, utilizing data from quarry blasts, we studied wave propagation in this region. The primary objective of the project is to investigate the near-surface P-wave velocity structure and factors that may affect it. We also analyzed the amplitude of signals versus distance and blast size. A network of up to 10 Raspberry Shake instruments around the NW Miami-Lakes mining area was deployed where four main quarry mines are recognized. More than 1600 blast waveforms were recorded from July 2019 to December 2022, and a catalog was created for measuring parameters. Later, we received detailed information about 447 blasts from the Miami-Dade Pilot Program of the Florida State Fire Marshal office and chose a subset of 165 high-quality events. We located these events in SEISAN and applied a grid search to reduce the misfit for the events' locations. Average P-wave velocity measured from travel time versus distance plots ranges from 4.6 to 5.4 km/s. In addition, first and second polynomials were fit to the data, and the average and root mean square errors were used to evaluate the goodness of fit. The result showed smaller error differences for the quadratic fit that suggests velocity changes with depth. Furthermore, peak-to-peak amplitudes of four distinct waves are compared with the changes in distance and explosive amounts of blasts. A decrease in amplitude versus distance with a combination of 1/r and 1/√r is observed.

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