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Lake sediments can unlock crucial information about past earthquakes, needed for seismic hazard modeling. USGS researchers and partners from the Woods Hole Oceanographic Institution deployed 10 seismographs in and around Skilak Lake, Alaska to learn more about past shaking events.
Understanding the timing, size, and location of past earthquakes is key for assessing seismic risks and creating hazard models. In earthquake prone regions like Southcentral Alaska, lake sediments are proving to be an especially reliable indicator of past seismic events.
Sediment cores from these lakes provide a detailed timeline of past seismic events. Geologists look for buried deposits from underwater landslides and turbidity flows triggered by earthquakes to determine when each event occurred.
To infer magnitudes and locations of older events, researchers need to know how lake basins respond to seismic waves arriving from different directions and earthquake sizes. The response of a lake basin to seismic shaking can be measured directly by installing seismographs in and around the basin.
Combining the geologic and seismic observations enables researchers to extend the modern record of seismic events further back in time.
A team of USGS scientists, in collaboration with partners from the Woods Hole Oceanographic Institution Ocean Bottom Seismic Instrument Center, are aiming to create a record of past earthquakes from Skilak Lake on the Kenai Peninsula of Alaska. In May 2024, they deployed two seismographs on the bottom of the lake and eight seismographs on land around the lake. Each instrument will collect data there for about 1 year.
The seismographs at the bottom of the lake were originally designed for use in the deep ocean. They weigh roughly 800 pounds and are typically deployed from large ships, so the research team needed to get creative to make them work for this effort. The scientists towed the seismographs to the lake and launched them from a flatbed trailer. On the water, they were supported by a float rig and towed by a small boat to the deployment locations where they were released and sank to the lake bottom. To recover them when the year is up, an acoustic pinger will be used to trigger the instruments to detach from an anchor.
At each land site, around 300 pounds of instrument components were transferred from the boat to shore, then carried to the sites. Installation involved digging holes for the post-hole seismometers and attaching a station box containing electronics and batteries.
Hannah Brewer (WHOI) and Tim Kane (WHOI) prepare to deploy an OBS on Skilak Lake. This is part of a USGS effort, in collaboration with partners from the Woods Hole Oceanographic Institution Ocean Bottom Seismic Instrument Center, to create a record of past earthquakes from Skilak Lake on the Kenai Peninsula of Alaska.
Hannah Brewer (WHOI) and Tim Kane (WHOI) prepare to deploy an OBS on Skilak Lake. This is part of a USGS effort, in collaboration with partners from the Woods Hole Oceanographic Institution Ocean Bottom Seismic Instrument Center, to create a record of past earthquakes from Skilak Lake on the Kenai Peninsula of Alaska.
The float rig supporting the OBS is towed to the deployment site on Skilak Lake. Hannah Brewer (WHOI) is on board. This is part of a USGS effort, in collaboration with partners from the Woods Hole Oceanographic Institution Ocean Bottom Seismic Instrument Center, to create a record of past earthquakes from Skilak Lake on the Kenai Peninsula of Alaska.
The float rig supporting the OBS is towed to the deployment site on Skilak Lake. Hannah Brewer (WHOI) is on board. This is part of a USGS effort, in collaboration with partners from the Woods Hole Oceanographic Institution Ocean Bottom Seismic Instrument Center, to create a record of past earthquakes from Skilak Lake on the Kenai Peninsula of Alaska.
Brian Andrews (USGS), Nathan Miller (USGS), and Rob Witter (USGS) installing post-hole seismometers and attaching a station box containing electronics and batteries.
Brian Andrews (USGS), Nathan Miller (USGS), and Rob Witter (USGS) installing post-hole seismometers and attaching a station box containing electronics and batteries.
USGS scientists work with academic collaborators from the University of Ghent (Belgium) to core earthquake-related submarine landslide deposits in Skilak Lake, Alaska.
USGS scientists work with academic collaborators from the University of Ghent (Belgium) to core earthquake-related submarine landslide deposits in Skilak Lake, Alaska.
Hannah Brewer (WHOI) and Tim Kane (WHOI) prepare to deploy an OBS on Skilak Lake. This is part of a USGS effort, in collaboration with partners from the Woods Hole Oceanographic Institution Ocean Bottom Seismic Instrument Center, to create a record of past earthquakes from Skilak Lake on the Kenai Peninsula of Alaska.
Hannah Brewer (WHOI) and Tim Kane (WHOI) prepare to deploy an OBS on Skilak Lake. This is part of a USGS effort, in collaboration with partners from the Woods Hole Oceanographic Institution Ocean Bottom Seismic Instrument Center, to create a record of past earthquakes from Skilak Lake on the Kenai Peninsula of Alaska.
The float rig supporting the OBS is towed to the deployment site on Skilak Lake. Hannah Brewer (WHOI) is on board. This is part of a USGS effort, in collaboration with partners from the Woods Hole Oceanographic Institution Ocean Bottom Seismic Instrument Center, to create a record of past earthquakes from Skilak Lake on the Kenai Peninsula of Alaska.
The float rig supporting the OBS is towed to the deployment site on Skilak Lake. Hannah Brewer (WHOI) is on board. This is part of a USGS effort, in collaboration with partners from the Woods Hole Oceanographic Institution Ocean Bottom Seismic Instrument Center, to create a record of past earthquakes from Skilak Lake on the Kenai Peninsula of Alaska.
Brian Andrews (USGS), Nathan Miller (USGS), and Rob Witter (USGS) installing post-hole seismometers and attaching a station box containing electronics and batteries.
Brian Andrews (USGS), Nathan Miller (USGS), and Rob Witter (USGS) installing post-hole seismometers and attaching a station box containing electronics and batteries.
USGS scientists work with academic collaborators from the University of Ghent (Belgium) to core earthquake-related submarine landslide deposits in Skilak Lake, Alaska.
USGS scientists work with academic collaborators from the University of Ghent (Belgium) to core earthquake-related submarine landslide deposits in Skilak Lake, Alaska.