Washington - Mount Saint Helens – latest activity : 1980 to present
Prior to 1980, Mount St. Helens formed a conical, youthful volcano sometimes known as the Fuji-san of America. During the 1980 eruption the upper 400 m of the summit was removed by slope failure, leaving a 2 x 3.5 km horseshoe-shaped crater now partially filled by a lava dome. Mount St. Helens was formed during nine eruptive periods beginning about 40-50,000 years ago and has been the most active volcano in the Cascade Range during the Holocene. Prior to 2200 years ago, tephra, lava domes, and pyroclastic flows were erupted, forming the older St. Helens edifice, but few lava flows extended beyond the base of the volcano. The modern edifice was constructed during the last 2200 years, when the volcano produced basaltic as well as andesitic and dacitic products from summit and flank vents. Historical eruptions in the 19th century originated from the Goat Rocks area on the north flank, and were witnessed by early settlers.
(some text & images : Smithsonian Institution)
| SRC | Location | UTC Date/time | M | D | INFORMATION | |
| USGS | Mount St. Helens Area, Washington | May 21 08:03 AM | 2.5 | 6 | MAP I Felt It | |
| USGS | Mount St. Helens Area, Washington | Jan 31 04:01 AM | 2.6 | 5 | MAP I Felt It | |
| USGS | Mount St. Helens Area, Washington | Nov 13 19:52 PM | 2.6 | 1 | MAP I Felt It | |
| USGS | Mount St. Helens Area, Washington | Sep 28 13:46 PM | 2.7 | 9 | MAP I Felt It | |
| USGS | Washington | Jul 06 01:18 AM | 2.5 | 12 | MAP I Felt It | |
| USGS | Mount St. Helens Area, Washington | Mar 17 21:28 PM | 2.5 | 1 | MAP I Felt It | |
| USGS | Washington | Jan 25 10:51 AM | 3.4 | 8 | MAP I Felt It | |
| USGS | Washington | Jan 23 03:07 AM | 2.5 | 8 | MAP I Felt It | |
Washington - Mount Rainier – latest activity : 1882
Mount Rainier, at 4392 m the highest peak in the Cascade Range, forms a dramatic backdrop to the Puget Sound region. Large Holocene mudflows from collapse of this massive, heavily glaciated andesitic volcano have reached as far as the Puget Sound lowlands. The present summit was constructed within a large crater breached to the northeast formed by collapse of the volcano during a major explosive eruption about 5600 years that produced the widespread Osceola Mudflow. Rainier has produced eruptions throughout the Holocene, including about a dozen during the past 2600 years; the largest of these occurred about 2200 years ago. The present-day summit cone is capped by two overlapping craters. Extensive hydrothermal alteration of the upper portion of the volcano has contributed to its structural weakness; an active thermal system has caused periodic melting on flank glaciers and produced an elaborate system of steam caves in the summit icecap. Reported 19th-century eruptions have not left identifiable deposits, but a phreatic eruption may have taken place as recently as 1894.
(some text & images : Smithsonian Institution)
| SRC | Location | UTC Date/time | M | D | INFORMATION | |
| USGS | Washington | Mar 22 10:01 AM | 2.7 | 5 | MAP I Felt It | |
Washington - Mount Baker – latest activity : 1880
Mount Baker, the northernmost of Washington’s volcanoes, is a 3285-m-high glacier-clad andesitic stratovolcano constructed above the east flank of the eroded mid-Pleistocene Black Buttes volcano and SW of the early Pleistocene 4.5 x 8 km rhyodacitic Kulshan caldera. With the exception of the Schreibers Meadow cinder cone on the SE flank, which formed about 9800 years ago, Holocene volcanism has been confined to the central conduit. A major magmatic eruption at Mount Baker about 6500 years ago was the largest eruptive event at the volcano during the Holocene and was accompanied by a major collapse event that produced a lahars down the Nooksack drainage. Early settlers in the Puget Sound region as far away as Victoria, British Columbia observed 19th-century activity, all of which consisted of relatively minor phreatic eruptions. Sherman Crater, the historically active crater immediately south of the summit, has been the site of increased steam emission since 1975.
(some text & images : Smithsonian Institution)
| SRC | Location | UTC Date/time | M | D | INFORMATION | |
| USGS | Mount Baker Area, Washington | Dec 16 15:56 PM | 2.5 | 6 | MAP I Felt It | |
| ER | Mount Rainier, Washington (startup Record) | Jan 01 00:00 AM | 0.1 | 0 | MAP I Felt It | |
Washington - Glacier Peak – latest activity : before 1800
Glacier Peak, the most isolated of the Cascade volcanoes, rises to 3213 m above the rugged forested terrain of the Glacier Peak Wilderness Area in the North Cascades. Glacier Peak is a dacitic-andesitic stratovolcano with summit and flank lava domes; it resembles Mount St. Helens in its explosive vigor. More than a dozen glaciers descend its flanks, prompting its name. Although its summit towers 3000 m above surrounding valleys, the volcano was constructed above a high ridge and is itself less than 1000 m high. Repeated major explosive eruptions associated with lava dome growth during the late Pleistocene and Holocene deposited tephra over wide distances to the east. Voluminous pyroclastic flows and mudflows extended into the Puget Sound lowlands to the west and diverted several river courses into adjacent valleys. The latest eruption of Glacier Peak only a few hundred years ago was noted by indigenous Pacific Northwest Indians, and hot springs occur on its flanks.
(some text & images : Smithsonian Institution)
| SRC | Location | UTC Date/time | M | D | INFORMATION | |
| USGS | Glacier Peak Area, Washington | Dec 31 13:41 PM | 2.7 | 0 | MAP I Felt It | |
| ER | Glacier Peak, Washington (startup Record) | Jan 01 00:00 AM | 0.1 | 0 | MAP I Felt It | |






