East Coast landslide impacts from Puerto Rico to Vermont and in
Boulder, Colo., USA: In the U.S., we may often think of landslides as
primarily a West Coast problem, mostly plaguing the mountainous terrain of
California, Oregon, and Washington. A
at the upcoming GSA 2023 Joint Southeastern & Northeastern Section
Meeting in Reston, Virginia, USA, will highlight the major impacts of
landslides on the U.S. East Coast and what is being done to save lives and
deal with the damages.
Landslides are projected to be a growing concern as climate change produces
more extreme rainfall events that can destabilize slopes and trigger these
events. Research presented in the session will include investigations of
landslide hazards in Puerto Rico, Vermont, Pennsylvania, Michigan,
Tennessee, West Virginia, and southern and central Appalachia.
After Hurricane Maria in 2017, researchers documented more than 70,000 landslides
on the island of Puerto Rico. Geologist Stephen Hughes at the University of
Puerto Rico Mayagüez saw a gap in the monitoring and forecasting of
landslides on the island, and to fill that gap he started a research and
outreach program: Storm-induced Landslide Impact Dynamics on Environment
and Society in Puerto Rico (SLIDES-PR). Through partnership with the U.S.
Geological Survey, SLIDES-PR has developed a landslide susceptibility map
for the island and installed 14
real-time monitoring stations on landslide-prone slopes.
“These are shallow, relatively small landslides, but extremely widespread.
It doesn’t matter that it’s a small landslide if it comes through your
house,” says Hughes.
The monitoring stations measure soil moisture, pore pressure, and
groundwater level, collecting data every five minutes and sending it back
to the university every hour. The monitoring network has already saved
lives. During Hurricane Fiona in 2022, Hughes was able to use real-time
monitoring to warn the town of Naguabo that the soil moisture had crossed
the threshold for imminent slope failure, prompting evacuation before a
debris flow buried a home.
In addition to monitoring and forecasting, the SLIDES-PR program has
developed guides for residents to understand the warning signs for
landslides, what human activities can promote them, and ways to prepare and
cope after they happen. At the conference, Anishka Ruiz-Perea will share
the science and risk communication work done by SLIDES-PR
, and Kiara Cunillera-Cote
will present on the development of forecasting thresholds using the
data from monitoring stations.
In 2019, a hillside in
Vermont’s Mt. Mansfield State Forest failed
and generated a 12.5-acre landslide with a volume equivalent to 80
Olympic-sized swimming pools. The material formed a dam in Cotton Brook,
which eventually carried the influx of sediment to the nearby Waterbury
Smuggler’s Notch, one of the most popular tourist destinations in the
state, is a 1,000-foot high mountain gap that has seen
major rock slides over several decades, sometimes dropping boulders the
size of school buses onto the road below.
“We are convinced, just like many others, that as climate change gets more
extreme, we will generate more landslides and more sediment systems,”
explains Jonathan Kim of the Vermont Geological Survey,
who will present on the many approaches taken to assess, monitor and
mitigate landslide hazards
The Vermont Geological Survey has been collaborating with the University of
Vermont (Burlington) and Norwich University (Northfield, Vermont) to
establish comprehensive tools for monitoring
and understanding the risk of landslides in the state. These investigations
led to a Federal Emergency Management Agency (FEMA) buyout of a parcel
containing a large landslide that posed a threat of additional slope
failures in 1999. Rainfall and flooding during Hurricane Irene in 2011 led
to slope instability throughout the state, prompting the
development of statewide landslide protocols and the formation of a
statewide landslide database
that can be contributed to by landslide experts and residents.
The greater Pittsburgh region experienced record rainfall in February–April
of 2018 that triggered more than 200 landslides. Built on clay-rich
sedimentary rocks and with steep topography from downcutting by river
erosion, southwestern Pennsylvania is one of the more landslide-prone
regions in the country. The landslides are small and typically not deadly,
affecting residences, roads, streams, and other infrastructure. As a result
of the 2018 landslides, one natural gas pipeline ruptured, and the
resulting explosion destroyed a house and several other buildings.
“It’s very clear that this was a climatically anomalous circumstance. We
had a hugely anomalous amount of rain in February when Pittsburgh would
normally be getting snow and the ground would be frozen. The ground wasn’t
frozen, and almost all of the precipitation fell as rain. We had shallow
soil slides as well as deeper-seated slides that require bigger changes in
hydraulic conditions,” explains Helen Delano of the Pennsylvania Geological
Survey, who will present
about the record landslide year
at the conference.
While the scope of damage from the landslides was extensive, an application
for FEMA support was denied because the several months of increased
landslides were not deemed a single event. When considered as separate
events, they did not meet the threshold of damages required to declare a
federal disaster. Delano says the record-breaking year has increased
awareness at the state level of the need to prepare for landslides.
Clean-up from the landslides of 2018 remains ongoing.
Jonathan Kim, Vermont Geological Survey: Jon.Kim@vermont.gov
Benjamin DeJong, Vermont Geological Survey: Benjamin.DeJong@vermont.gov
Helen Delano, Pennsylvania Geological Survey: firstname.lastname@example.org
Stephen Hughes, University of Puerto Rico Mayagüez: email@example.com
Anishka Ruiz-Perea, University of Puerto Rico Mayagüez:
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