COMPARING THE SEDIMENT SIGNATURE OF HURRICANE SANDY WITH HISTORIC AND PREHISTORIC STORM DEPOSITS

Hurricane Sandy (2012) presented an example of the destructive potential of hurricanes. Studies of changes in the frequency of such storms can provide insights that allow for better understanding the climatic forcing of intense hurricane activity. However, this effort is impeded by the lack of data; reliable records of major hurricane strikes reaches only to the 19^th century. Thus, finding patterns in changes in storm frequencies is extremely difficult. By contrast, the sedimentological record can extend the historic record back thousands of years.

In order to compare the effects of Hurricane Sandy to historic and pre-historic storms in the region, we collected nearly 30 vibracores from the New York and New Jersey region in the immediate aftermath of the storm. Target coring locations were chosen to maximize the likelihood of capturing sediments deposited by Sandy. Cores were analyzed (LOI, grain-size analysis), and course sediment layers were identified as storm proxies. Chronology was established using both radiocarbon dating and 137Cs (a product of nuclear weapons testing) dating techniques.

No surface layers corresponding to Hurricane Sandy were present in any of the initial sediment cores collected. This indicates that overwash fans from Hurricane Sandy are rare in backbarrier environments. However, evidence of numerous other historic events is prevalent throughout a number of the cores. In particular, overwash deposits associated with the 1821 hurricane are present in nearly all study sites. Thus, we hypothesize that large, slow-moving, but relatively weak storms such as Sandy may be less likely to leave deposits than smaller sized storms with stronger winds and higher waves. Cores from Crab Meadow, Long Island were analyzed and an age model is being established based on these cores to constrain the chronology of the intense storms affecting this region. Computer modeling using NOAA’s SLOSH simulation provides local storm-surge data for storms in this record and is used to estimate the power of some of these more modern events. Few storm-event layers are identified in the Crab Meadow cores between approximately 500 and 1000 B.P., which closely matches similar quiescent periods recorded for this region in earlier studies.