SPECIAL PUBLICATION NO. 57


 4. Locations of nearby sinkholes or neighbors who have filed
 sinkhole claims, or sinkholes known to have been filled.
 Locations of houses or other structures that have been
 remediated because of a sinkhole loss. Determine if nearby
 structures on adjacent property have been grouted. Collect
 dates if available.

5. Geophysical Site Characterization

 a. Concurrent with or following the site reconnaissance. Surface geophysical
 methods should be used (in most cases) to characterize subsurface geology,
 identify anomalous subsurface conditions, and to provide guidance in selecting
 locations for invasive tests such as trenches, borings, etc.

 b. The investigation method or methods selected should be sufficient to allow
 interpretation to be able to discern shallow conditions that are likely to have
 directly affected the structure in order to conform to the definition of "sinkhole
 loss" contained in 627.706 F.S.

 c. When making field measurements, it is highly recommended that more than one
 set of data be used to aid in an interpretation. When two or more sets of different
 data agree, there is a higher degree of confidence in the results and the associated
 interpretation. For example, if a Ground Penetrating Radar survey indicates the
 presence of broken dipping strata and a test boring placed in the center of the
 anomaly identifies very loose sediments or voids; we can have a high degree of
 confidence in the interpretation of the presence of an active sinkhole.

 d. Applicable geophysical investigation methods which may be useful include;

 i. Ground penetrating radar (GPR, including 3D-GPR),

 ii. Electrical resistivity soundings or profiling (ER),

 iii. 2-D Multi-electrode resistivity (2DER or MER),

 iv. Capacitive-coupled resistivity (CCR, Ohm-Mapper),

 v. Micro Gravity survey (MGS),

 vi. Magnetometer, Metal Detector, or EM31 measurements (often used to
 identify buried utilities which may impact other geophysical
 measurements),

 vii. Surface Wave measurements including Multispectral Analysis (MASW)
 and Spectral Analysis (SASW),

 viii. Choice of geophysical method and data reduction techniques should be in
 accordance with relevant ASTM or other accepted methods and chosen as