Mud Creek Slide

Mud Creek Slide
Name	Mud Creek Slide
Date	2017-05-31
Location	Big Sur, Monterey County, California
Type	Landslide
Cause	Heavy El Niño-linked rainfall, coastal erosion, seismicity

Mud Creek Slide

Mud Creek Slide was a catastrophic coastal landslide that occurred near Highway 1 along the Big Sur coastline in Monterey County, California in 2017. The event produced an immense debris field that buried a section of California State Route 1 and altered the local coastal geomorphology, prompting responses from Caltrans, Monterey County officials, and federal agencies including the Federal Highway Administration and the United States Geological Survey. The slide has been cited in studies by researchers at Stanford University, University of California, Berkeley, and California State Polytechnic University, Humboldt as a case study in rapid coastal slope failure.

Overview

The slide occurred on May 20, 2017, when a mass of saturated soil, bedrock, and vegetation detached from a steep coastal bluff east of Pacific Ocean surf and descended to the shoreline, forming a debris dam that blocked Highway 1 and created a new promontory. Local responders from the California Highway Patrol and personnel from Caltrans District 5 implemented emergency closures and traffic reroutes. Media coverage by outlets such as the Los Angeles Times, San Francisco Chronicle, and Monterey Herald brought national attention and prompted scientific investigations by teams affiliated with the U.S. Geological Survey and academic institutions.

Geology and Causes

The slide area sits within the Santa Lucia Range and is underlain by sedimentary rocks of the Franciscan Complex and Miocene marine sediments, influenced by active uplift associated with the nearby San Andreas Fault system and related coastal faulting. Climatic drivers included intense winter precipitation linked to the 2016–2017 El Niño pattern and atmospheric river storms that increased pore-water pressures in colluvial soils derived from weathered serpentine and shale. Wave-driven coastal erosion at the toe of the slope, attributed to high-energy swell events from the Pacific Ocean and seasonal storm cycles, removed lateral support. Local seismicity, including small earthquakes recorded by the California Integrated Seismic Network, may have provided additional dynamic loading that triggered failure. Geotechnical analyses referenced stratigraphic logs, shear-strength tests, and slope-stability modeling used by Caltrans and academic partners.

Chronology of the Slide

Preconditioning began with months of above-average rainfall in winter 2016–2017 recorded by the National Weather Service and National Oceanic and Atmospheric Administration, followed by progressive retreat of the bluff face observed by local rangers at Pfeiffer Big Sur State Park and remote-sensing teams at NASA. The main failure on May 20, 2017 rapidly transported millions of cubic meters of material to the shore, sealing off a coastal cove and severing State Route 1 at a location between Garrapata State Park and Julia Pfeiffer Burns State Park. Emergency assessments by Caltrans occurred within days, followed by geological mapping by the USGS and sediment-transport studies by researchers from University of California, Santa Cruz and San Diego State University.

Impacts and Damage

The slide destroyed a section of California State Route 1, obstructed coastal access, and necessitated permanent detours that affected tourism hubs such as Carmel-by-the-Sea, Big Sur Station, and Hearst Castle visitor routes. Economic impacts extended to hospitality and recreation operators, including businesses in Monterey County and the Big Sur lodging sector. The failure altered nearshore bathymetry, impacting kelp forest habitats monitored by scientists at the Monterey Bay Aquarium Research Institute and fisheries biologists from the California Department of Fish and Wildlife. One fatality was reported, and extensive infrastructure repairs were required by Caltrans with funding coordination involving the Federal Highway Administration and state emergency funds.

Response and Remediation

Immediate response actions included road closures enforced by the California Highway Patrol, geotechnical reconnaissance by Caltrans District 5, and environmental assessments conducted in accordance with California Environmental Quality Act processes administered by Monterey County planning staff. Remediation options evaluated ranged from constructing engineered cuts and retaining structures to rerouting State Route 1 inland; Caltrans ultimately pursued temporary and long-term planning that balanced historic preservation interests raised by the National Park Service and state parks agencies. Stabilization efforts included drainage improvements, slope grading, and monitoring installations overseen by consulting firms and academic partners, while restoration of coastal habitats involved collaboration with the California Coastal Conservancy and local conservation organizations.

Monitoring and Future Risk Assessment

Post-event monitoring has used repeat aerial photography from National Aeronautics and Space Administration, interferometric synthetic aperture radar analyzed by teams at Jet Propulsion Laboratory, terrestrial lidar surveys conducted by USGS and university groups, and in situ instruments such as inclinometers and piezometers installed by Caltrans and academic collaborators. Regional risk assessments incorporate climate projections from the Intergovernmental Panel on Climate Change scenarios, sea-level rise models by NOAA, and landslide susceptibility mapping techniques employed by the USGS and state geologists. Ongoing studies by Stanford University, University of California, Berkeley, and University of California, Santa Cruz aim to refine probabilistic forecasts for coastal slope failures along the Central Coast of California and to inform resilience planning by Monterey County and state agencies.

Category:Landslides in California Category:Big Sur