Archived from:

Mud / Waterflows around Mount Rainier
Major Mudflows


Age (years)

Volume (km)

River Valley

Area Reached

Tahoma Lahar  <500 <0.15 Tahoma Creek 
Nisqually River
Probably to Elbe 
Electron Mudflow  530-550 0.26 Puyallup River   Puget Sound Lowland 
Unnamed Mudflow   1050-1000 >0.30 Puyallup River  At least to Mowich River; possibly Puget Sound
Round Pass Mudflow  2170-2710 Puyallup River   Puget Sound Lowland 
Osceola Mudflow  4500-5000 White River and West Fork Puget Sound 

Smaller Mudflows


Age or Date

Volume (km

River Valley

Area Reached

Little Tahoma Peak
1963  0.01 White River White River Campground
Tahoma Glacier Avalanche 1910-1930  0.01 Puyallup River Below end of glacier
Round Pass Mudflow 2610-2790 <0.01 Tahoma Creek; Nisqually River End of Tahoma Creek
Pre-Y level Lahar >3400 Puyallup River; Tahoma Creek Unknown
Paradise Lahar 4500-5000 0.1 Paradise River; Nisqually River At least to National

Large Muddy Outburst Floods

River Valley and Flow  

Age or Date

Area Reached

White River (including West Fork):
  • Gravel-rich flow
~1550 AD At least to Mud Mountain Reservoir
  • At least one lahar
>1480 AD At least 5-10 mi outside of Park boundary
  • Lahar in West Fork
<2200 At least to confluence of forks
  • Lahar?
<2200 possibly to Puget Sound
  • Many lahars 
<2200  Probably to Puget Sound 
  • At least 5 lahars 
<4500  Probably to edge of Puget Sound Lowland 
  • At least two lahars 
>5000  Puget Sound Lowland 
Cowlitz River: 
  • At least two flows 
1480 AD  
At least 10 km downstream of Packwood  
  • Lahar 
<2200  Packwood 
  • At least 3 lahars 
<3400  At least to Park boundary on Muddy Fork 
Nisqually River: 
  • Outburst flow on Kautz Creek
1947 AD  Below confluence with Nisqually River
  • Lahar 
1480 AD 
At least to Elbe 
  • Parts of Tahoma Lahar
1480 AD 
At least to Elbe 
  • Lahar runout 
<2500  At least to National 
  • Lahar runout 
<2500  To Elbe 
  • Runout from National Lahar
<2200  Puget Sound 
  • Lahar runout 
<3400  At least to Ashford 
  • Large lahar runout 
>3400  Probably to Puget Sound Lowland 
Puyallup River: 
  • Lahar runout 
<3400  Puget Sound Lowland 
  • Lahar  
<3400  Puget Sound Lowland 
  • Lahar runout 
3400  Puget Sound Lowland 
Carbon River: 
  • Lahar runout 
1480 AD 
At least 5 km below end of glacier 
  • Lahar runout 
1480 AD 
8-10 km beyond end of glacier 

Mudflow and muddy outburst floods are descriptive terms used here in place of technical terms such as cohesive debris flows used in the original report. These data cover a range of flows consisting of differing proportions of mud and water. Mudflows are like huge rivers of mud. These flows always leave deposits of mud that later dry to rich soil. Muddy outburst floods are more like floods of muddy water. These flows may be erosive or may leave deposits. Small muddy flows and glacial outbursts of mostly water are not listed because they are difficult to detect from river deposits. Lahar refers to the whole range of muddy flows. Lahar runout refers to muddy water flowing out of a mudflow that has stopped.

Some Properties of Mud/Water Flows

Giant Mudflows

Large Mudflows

Muddy Floods

Flow Volume >3 km 0.1-0.5 km3 <0.1 km3
Flow Speed at:

Volcano Base

>40 m/s >30 m/s 10 m/s

1 km out on plain

10 3-4
Flow Height at:

Volcano Base 

200 m  50 m  15 m 

1 km out on Plain 

30  10  1-3 

These data are adapted from U.S. Geological Survey Open-File Report 90-385.

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