Unanswered Questions About the Deadly Washington Mudslide

The death toll rose to 28 on Tuesday.

A Catastrophic Landslide - One of the deadliest landslides in recent U.S. history struck the small town of Oso, Washington, earlier this month. The death toll increased to 28 on Tuesday as the Snohomish County medical examiner's confirmed that 22 of the victims have been positively identified. As the search for the missing and clean-up continues, BET.com takes a closer look at the mudslide to find out how it occured and why. — Dominique Zonyeé (@DominiqueZonyee)(Photo: AP Photo/ The Seattle Times, Marcus Yam)

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A Catastrophic Landslide - One of the deadliest landslides in recent U.S. history struck the small town of Oso, Washington, earlier this month. The death toll increased to 28 on Tuesday as the Snohomish County medical examiner's confirmed that 22 of the victims have been positively identified. As the search for the missing and clean-up continues, BET.com takes a closer look at the mudslide to find out how it occured and why. — Dominique Zonyeé (@DominiqueZonyee)(Photo: AP Photo/ The Seattle Times, Marcus Yam)

What Creates a Deadly Mudslide? - Mudslides are a type of landslide, where mud quickly moves down a hillside. Deadly mudslides are caused when the hillsides become saturated with water from river overflow due to excessive rainfall.(Photo: Washington State Dept of Transportation via Getty Images)

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What Creates a Deadly Mudslide? - Mudslides are a type of landslide, where mud quickly moves down a hillside. Deadly mudslides are caused when the hillsides become saturated with water from river overflow due to excessive rainfall.(Photo: Washington State Dept of Transportation via Getty Images)

What Happened in Washington? - Loose sand-like material laid down near the Stilliguamish River by glacial lakes less than 16,000 years ago, according to Washington State geologist Dan McShane of Stratum Group, who writes a blog called Reading the Washington Landscape. Over time the loose material was cut down — creating hillsides. When oversaturated with water, the hillsides had a history of collapsing. (Photo: Lindsey Wasson/The Seattle Times-Pool/Getty Images)

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What Happened in Washington? - Loose sand-like material laid down near the Stilliguamish River by glacial lakes less than 16,000 years ago, according to Washington State geologist Dan McShane of Stratum Group, who writes a blog called Reading the Washington Landscape. Over time the loose material was cut down — creating hillsides. When oversaturated with water, the hillsides had a history of collapsing. (Photo: Lindsey Wasson/The Seattle Times-Pool/Getty Images)

How Much Rainfall Does It Take? - Arlington, a neighboring town, reported 7.33 inches of rain so far this month, which is almost double the average for March. Although it wasn’t raining when the mudslide occurred on Saturday, previous rainfall left the mud so wet and thick, firefighters and rescue crew members were buried in mud and had to be pulled out by ropes.(Photo: Christopher Furlong/Getty Images)

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How Much Rainfall Does It Take? - Arlington, a neighboring town, reported 7.33 inches of rain so far this month, which is almost double the average for March. Although it wasn’t raining when the mudslide occurred on Saturday, previous rainfall left the mud so wet and thick, firefighters and rescue crew members were buried in mud and had to be pulled out by ropes.(Photo: Christopher Furlong/Getty Images)

Can Other Things Cause a Mudslide? - The mudslide could also be a result of Mother Nature, according to John Pennington, Snohomish County's director of emergency management. He told reporters that officials identified a 1.1 magnitude earthquake that occurred in the area on March 10, but it remains unclear if that definitely played a role in the disaster.(Photo: David Ryder/Getty Images)

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Can Other Things Cause a Mudslide? - The mudslide could also be a result of Mother Nature, according to John Pennington, Snohomish County's director of emergency management. He told reporters that officials identified a 1.1 magnitude earthquake that occurred in the area on March 10, but it remains unclear if that definitely played a role in the disaster.(Photo: David Ryder/Getty Images)

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How Bad Was the Washington Mudslide? - The disaster ranks as one of the deadliest U.S. landslides in recent years, after 10 people died when a landslip engulfed homes in La Conchita, California, in 2005. The slide also buried a milelong stretch of Highway 530 under at least 20 feet of mud.(Photo: AP Photo/seattlepi.com, Joshua Trujillo)

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How Bad Was the Washington Mudslide? - The disaster ranks as one of the deadliest U.S. landslides in recent years, after 10 people died when a landslip engulfed homes in La Conchita, California, in 2005. The slide also buried a milelong stretch of Highway 530 under at least 20 feet of mud.(Photo: AP Photo/seattlepi.com, Joshua Trujillo)

How Often Do Landslides Occur? - Landslides of various kinds occur in all 50 states, killing about 25 people and causing $1 billion to $2 billion in damages every year, according to the U.S. Geological Survey.(Photo: AP Photo/Elaine Thompson)

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How Often Do Landslides Occur? - Landslides of various kinds occur in all 50 states, killing about 25 people and causing $1 billion to $2 billion in damages every year, according to the U.S. Geological Survey.(Photo: AP Photo/Elaine Thompson)

Was Oso at Risk? - According to experts, the Oso Landslip was 20 years in the making. "This landslide is known to have moved in 1988, and went through a second phase of movement in 2006," David Petley, a landslide researcher at Durham University in the U.K. and author of The Landslide Blog, wrote in a blog post from 2009.(Photo: Office of the Governor via Getty Images)

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Was Oso at Risk? - According to experts, the Oso Landslip was 20 years in the making. "This landslide is known to have moved in 1988, and went through a second phase of movement in 2006," David Petley, a landslide researcher at Durham University in the U.K. and author of The Landslide Blog, wrote in a blog post from 2009.(Photo: Office of the Governor via Getty Images)

Were There Warning Signs? - Although some experts said “Washington mudslides are hard to predict,” The Seattle Times obtained a 1999 report filed by the U.S. Army Corps of Engineers warning of “the potential for a large catastrophic failure" on the hill where the mudslide happened. Despite the report's findings, construction in the area persisted, causing a smaller 2006 mudslide. (Photo: Lindsey Wasson/The Seattle Times-Pool/Getty Images)

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Were There Warning Signs? - Although some experts said “Washington mudslides are hard to predict,” The Seattle Times obtained a 1999 report filed by the U.S. Army Corps of Engineers warning of “the potential for a large catastrophic failure" on the hill where the mudslide happened. Despite the report's findings, construction in the area persisted, causing a smaller 2006 mudslide. (Photo: Lindsey Wasson/The Seattle Times-Pool/Getty Images)

The Aftermath - A total of 156 workers and 50 National Guard members continued to look through the debris and muck for survivors on Tuesday in hopes that there are air pockets keeping the more than 170 missing people alive. However, the search has not been easy as quicksand-like conditions forced rescuers to abort their search mission on Sunday.(Photo: Washington State Patrol via Getty Images)

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The Aftermath - A total of 156 workers and 50 National Guard members continued to look through the debris and muck for survivors on Tuesday in hopes that there are air pockets keeping the more than 170 missing people alive. However, the search has not been easy as quicksand-like conditions forced rescuers to abort their search mission on Sunday.(Photo: Washington State Patrol via Getty Images)

American Red Cross - The Red Cross has set up shelters in communities impacted by the storm. In addition, you can click here to learn how you can donate blood or click here to make a monetary donation online. (Photo: Courtesy of The American Red Cross)

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What You Can Do to Help - The Red Cross has seen an outpouring of food and clothing donations. But monetary donations are needed as well. For those with lost loved ones, call 425-388-5088, or visit Safe and Well.(Photo: Courtesy of The American Red Cross)