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4. 1 . 10. 2 Earthquakes Hazard Identification . Although Florida is not usually considered tc be a state subject to earthquakes , several minor shocks have occurred over time , but on y one caused any damage ( USDOI , USGS , 2004 ) . Historic Events. • In January 1879 , a shock occurred near St. Augustine that is reported to have knocked plaster from walls and articles from shelves . Similar effects were reported in Daytona Beach . The shock was felt in Tampa , throughout central Florida , and in Savannah , Georgia as well ( USDOI , USGS , 2004 ) . • In January 1880 another earthquake occurred , this time with C ba as the focal point . Shock waves were sent as far north as the town of Key est ( USDOI , USGS , 2004) . • In August 1886 , Charleston , South Carolina was the center of shock that was felt throughout northern Florida . It rang church bells in St. Augustine and severely jolted other towns along sections of Florida ' s east coE st . Jacksonville residents felt many of the strong aftershocks that occurred in eptember, October , and November 1886 ( USDOI , USGS , 2004 ) . In June 1893 , Jacksonville experienced a minor shock that lasted about 10 seconds . Another earthquake occurred in October 1893 , which also did not cause any damage ( USDOI , USGS , 2004 ) . In November 1948 , doors and windows rattled in Captiva Island , west of lar Ft . Myers . It was reportedly accompanied by sounds like distant heavy explosions ( USDOI , USGS ) . • In November 1952 , a slight tremor was felt in Quincy , a town located 20 miles northwest of Tallahassee . Windows and doors rattled , but no damage was reported ( USDOI , USGS ) . Best available data do not indicate that there have been any earthquakes in Indian River County or the municipalities . 4. 1 . 10. 3 Sinkholes and Subsidence Hazard Identification . Sinkholes are a common feature of Florida' s landscape . They are only one of many kinds of karst landforms , which include caves , disappearing streams , springs , and underground drainage systems , all of which occur in Florida . Karst is a generic term that refers to the characteristic terrain produced by erosional processes associated with the chemical weathering and dissolution of limestone or dolomite , the two most common carbonate rocks in Florida . Dissolution of carbonate rocks begins when they are exposed to acidic water. Most rainwater is slightly acidic and usually becomes more acidic as it moves through decaying plant debris . Limestones in Florida are porous , allowing the acidic water to percolate through them , dissolving some limestone and c rrying it away in solution . Over time , this persistent erosion process has created extensive underground voids and drainage systems in much of the carbonate rocks throughout the state . Collapse of overlying sediments into the underground cavities produces sinkholes ( Florida Geological Survey , 1998 ) . 4-48