New LiDAR detection may help save lives in the future
LiDAR shows what the San Andreas fault looks like through the heavy forest cover (Credit: USGS).
LiDAR detection may help save lives in the future
Interim Mitigation & Recovery Section Manager John Schelling still remembers visiting Christchurch, New Zealand following a devastating 6.3 earthquake back in 2011 that caused $30 billion worth of damage, killed 185 people and toppled the city’s 132-year-old iconic bell tower.
The earthquake happened about six months after a 7.1 earthquake hit the area. However, the 6.3 earthquake on Feb. 22, 2011 was much shallower. As a result, the damage was much worse.
Making the situation a bit more eye-brow raising, Schelling notes, the earthquake occurred in an unexpected area.
“The fault that caused the earthquake was unknown,” said Schelling, with the Washington Emergency Management Division. “It wasn’t mapped.”
Schelling was among a three-person panel before the state House Committee on Agriculture & Natural Resources on March 11, cautioning that the state of Washington could face a similar situation if the state doesn’t invest in proper technology to get a better idea of the kind of earthquake faults, prone landslide areas and tsunami inundation areas that could be in our neck of the woods.
“We have very similar faults,” Schelling testified. “Very shallow faults throughout our state and without identifying where they are and how frequently the rupture and looking at the consequences of these events, we’re not as prepared as we need to be. Having a better understanding of geological hazards will make a difference both now and in the future.”
Schelling sat alongside Dave Norman, a state geologist with the state Department of Natural Resources, and Tom Carlson, with the U.S. Geological Survey, to pitch the state to invest in LiDAR – which uses high quality light detection from an airplane to survey the environment and create high resolution images. Key to the technology is its ability to use lasers to cut through beyond vegetation and trees to determine the shape of slopes and the terrain. An active sensor emits between 40,000 and 400,000 infrared laser pulses per second to collect data that is later analyzed by scientists and the data can be collected in the daylight hours or at night and cloud cover is not an issue, either, the experts told legislators.
The LiDAR pictures above from 2013 show landslide deposits in the area of the devastating Oso Landslide on Highway 530.
The slide notes that the red cross-hatched area marks the area of the deposits from the March 22, 2014 landslide.
Colored areas show older landslide deposits (Credit: USGS).
Carlson notes that LiDAR was used before and after the devastating landslide on Highway 530 at Oso last year to allow specialists to get a better understanding of the way the landslide acted – but there’s much more to be done.
“This helps emergency management and local officials make decisions on what stability is like,” Norman added.
Norman notes that the state has only done about a third of the needed mapping along the Washington state coastline to prepare tsunami inundation maps compared with Oregon, which has done models for its coast three times. By coincidence, the testimony took place on the fourth anniversary of the devastating Japanese tsunami.
Carlson said that LiDAR uses also extend to discovering agriculture drainage problems.
Legislation under consideration by the state would invest $6.5 million to fund 14 positions to map geologic hazards, model tsunami inundation hazards, collect subsurface data and collect and analyze LiDAR data. The information would also create a centralized database that can be used by the public and decision makers. Senate Bill 5088 passed unanimously out of the state Senate on Feb 25 and is now in the House for consideration.
“Geological hazard assessments are really critical and form the original underpinning of emergency planning that takes place in Washington state,” Schelling testified. “Without having a solid scientific understanding of the myriad of natural resources threats including volcanic lahars, magnitude 9-plus earthquakes, 30-foot tsunamis, devastating landslides and without appropriately characterizing these hazards, we can’t plan for them appropriately to respond to them and, perhaps even more importantly, to mitigate against them.”
Tsunami inundation maps were prepared using LiDAR (Credit: DNR).
State Rep. Brian Blake, who chairs the state House Committee on Agriculture & Natural Resources, asked. “Having worked with aerial photos a lot and landscapes and the various generations of LiDAR over the years, it looks to me like the information you will capture with this program, the technology is pretty mature now? Are the gains in the future going to be interpreting the data we can capture here or in two years from now is there going to be a shinier product out there that we’re going to go want to do this again?”
The panel told Blake that there will always be gains in technology, but the resolution level LiDAR is at today works at a level much better than years ago and it will take time to map critical areas of the state.
Schelling compared the technology to the way doctors use an X-Ray machine to diagnose broken bones and sprains.
“LiDAR works much the same way for experts like Tom and Dave to help them look inside the earth and see the ground cover, see where earthquake faults exist, see where future landslides might occur, and it really helps them to accurately identify faults that otherwise wouldn’t be visible since the length of the fault is directly proportional to the type of earthquake that can be generated,” Schelling said. “If we don’t understand where these faults are, if we don’t understand how long they are or how active they are or how frequently they rupture, then we can’t appropriately plan for that.”
Presentation from USGS can be downloaded here (PDF).
Presentation from DNR can be downloaded here (PDF).
The legislation is House Bill 5088.