e-mail: training@masw.com
Karst Sinkholes at the USF GeoPark

Karst is formed from the dissolution of soluble rocks such as limestone, dolomite, and gypsum.  It is characterized by underground drainage
systems with sinkholes and caves.  Sinkhole development in cultural area always threatens human life and property integrity. Early detection
and accurate characterization of its subsurface development, therefore, have become crucially important issues among relevant communities
including geotechnical engineers.

Sinkhole investigation has been one of the major issues in multidisciplinary fields including geophysics, geology, geotechnical engineering,
geomorphology, remote
sensing, etc., resulting in a vast number of publications in all these fields. Particularly, it has been the major purpose in
geotechnical karst investigation sometimes considered analogous to the needle in the haystack problem. From the standpoint of geophysical
investigation, it has been the detection of highly localized anomalies such as voids and cavities that often challenged resolution limits of such
commonly used methods as GPR, resistivity, and seismic surveys. Although each of these geophysical approaches is continuously evolving in
its own way in methodology and measuring instruments, none of them is exclusively superior in every aspect over others.
The State of Florida may have possibly the most sinkhole areas developed
within the cultural area of the world because of the state-wide dominance of
Karst geology. Concern for sinkhole related public safety is growing rapidly
and the number of litigations in residential and commercial areas has grown
exponentially in recent years. A variety of geophysical methods—including
ground-penetrating-radar (GPR), resistivity, and MASW—have been
applied to effectively characterize sinkhole-related subsurface features.
Considering the most important subsurface property is usually the stiffness
distribution in and around an existing or developing sinkhole area, the
MASW method that generates near-surface profiles of shear-wave velocity
(Vs), a direct indicator of stiffness, seems to be one of the most effective
geophysical approaches.

The GeoPark in the campus of USF was built in 2001 as a resource site for
on-campus geological teaching and research, and nowadays continues to
serve as a demonstration site for a variety of courses including
hydrogeology, geophysics, and geomorphology.

The field demonstration part of the MASW training course, scheduled in the
early afternoon, will conduct an actual MASW survey over a sinkhole area
known to exist in this GeoPark to evaluate the approach’s potential
effectiveness. This area was intensively investigated previously by geologic
(e.g., well drilling), geotechnical (e.g., CPT), and geophysical approaches
(e.g., GPR).  The geologic cross section of the survey area (shown below)
was compiled from all previous survey results.

The MASW survey will use a 24-channel land streamer equipped with 4.5-
Hz geophones spaced at 5-ft intervals.  It will attempt to collect multiple (e.
g., 20 or more) field records at successive surface locations along the
preset linear survey line that runs over the target sinkhole.  A 20-lb sledge
hammer (or accelerated weight drop) will be used as a seismic source to
generate surface waves.  Each participant will then process this data set
during the subsequent data-processing tutorial session in the classroom.
Sinkhole-Site MASW Training Course - University of South Florida (USF)

    We are pleased to announce the offering of an MASW training course at the University of South Florida (USF), Tampa, FL, on
    Friday, February 15, 2019.  This course will be hosted by Professor Sarah Kruse in the School of Geosciences at USF, with field
    operations arranged by GeoView Inc.  This day-long (8am-5pm) course will cover theory, applications, field survey, and data
    analysis. The course will include an on-site demonstration of MASW data acquisition at the USF GeoPark where there are multiple
    cover-collapse sinkholes. Each participant will have an opportunity to process this data set during the subsequent data-analysis
    tutorial session.     

    The GeoPark in the USF campus has been an invaluable site for geological and geophysical studies.  Multiple cover-collapse
    sinkholes exist on site (more information is provided below).  The course will therefore provide a unique opportunity for hands-on
    experience of MASW surveys in one of the most environmentally hazardous and geophysically challenging near-surface settings.  

    Registration is limited to a first-come, first-served basis.  The site will be open until January 15, 2019.  Student registrations are
    available.  Registration forms (PDF) can be downloaded here.  For more information, please email to training@masw.com.

    Park Seismic LLC