CVO reported that the strongest earthquake in the Mount Hood area in decades occurred on 29 June at 0736. The widely felt M 4.5 event was located ~4.5 km S of the summit at a depth of 6 km. Hundreds of aftershocks followed, including two greater than M 3. Typically, several earthquake swarms occur each year at Mount Hood.

26 June 2002            Back to Top

CVO reported that the strongest earthquake in the Mount Hood area in decades occurred on 29 June at 0736. The widely felt M 4.5 event was located ~4.5 km S of the summit at a depth of 6 km. Hundreds of aftershocks followed, including two greater than M 3. Typically, several earthquake swarms occur each year at Mount Hood.

Sources: Associated Press , US Geological Survey Cascades Volcano Observatory (CVO)

12 September 2001            Back to Top

The USGS Cascades Volcano Observatory reported that a minor earthquake swarm occurred at Mount Hood from 9 September until at least 14 September. About 25 events were detected, with a maximum magnitude of 2.9. The epicenters of the earthquakes were ~8 km SSW of the volcano's summit at depths of 1-7 km. These types of swarms occur once or twice per year at Mount Hood.

Sources: US Geological Survey Cascades Volcano Observatory (CVO)

17 January 2001            Back to Top

The Cascades Volcano Observatory (CVO) reported that during 10-20 January a swarm of 13 earthquakes with magnitudes ranging from 0.2-2.0 occurred in an area about 4-8 km SSE of the summit at a depth of 4-7 km. This activity is not abnormal; Mount Hood averages one to two small swarms a year, with the last swarm occurring in May 2000. The current swarm consisted of fewer and smaller events than is typical, but it may not have yet ended.

Sources: Associated Press , US Geological Survey Cascades Volcano Observatory (CVO)

Below is a summary of eruption dates and Volcanic Explosivity Indices (VEI).

The following references are the sources used for data regarding this volcano. References are linked directly to our volcano data file. Discussion of another volcano or eruption (sometimes far from the one that is the subject of the manuscript) may produce a citation that is not at all apparent from the title. Additional discussion of data sources can be found under Volcano Data Criteria.

Cameron K A, Pringle P T, 1987. A detailed chronology of the most recent major eruptive period at Mount Hood, Oregon. {Geol Soc Amer Bull}, 99: 845-851

Cameron K A, Pringle P T, 1991. Prehistoric buried forests of Mount Hood. {Oregon Geol}, 53: 34-43

Crandell D R, 1980. Recent eruptive history of Mount Hood, Oregon, and potential hazards from future eruptions. {U S Geol Surv Bull}, 1492: 1-81

Cribb J W, Barton M, 1997. Significance of crustal and source region processes on the evolution of compositionally similar calc-alkaline lavas, Mt. Hood, Oregon. {J Volc Geotherm Res}, 76: 229-249

Harris S L, 1988. {Fire Mountains of the West: the Cascade and Mono Lake Volcanoes}. Missoula, MT: Mountain Press, 379 p

Hildreth W E, 2007. Quaternary magmatism in the Cascades--geologic perpectives. {U S Geol Surv Prof Pap}, 1744: 1-125

IAVCEI, 1973-80. Post-Miocene Volcanoes of the World. {IAVCEI Data Sheets, Rome: Internatl Assoc Volc Chemistry Earth's Interior}.

Katsui Y (ed), 1971. List of the World Active Volcanoes. {Volc Soc Japan draft ms}, (limited circulation), 160 p

Sherrod D R, Smith J G, 1990. Quaternary extrusion rates of the Cascade Range, northwestern United States and southern British Columbia. {J Geophys Res}, 95: 19,465-19,474

Wise W S, 1969. Geology and petrology of the Mount Hood area: a study of High Cascades volcanism. {Geol Soc Amer Bull}, 80: 969-1006

Wise W S, 1968. Geology of the Mount Hood volcano. {Oregon Dept Geol Min Ind Bull}, 62: 81-98

Wood C A, Kienle J (eds), 1990. {Volcanoes of North America}. Cambridge, England: Cambridge Univ Press, 354 p

Mount Hood, Oregon's highest peak, forms a prominent backdrop to the state's largest city, Portland. The eroded summit area of Mount Hood consists of several andesitic or dacitic lava domes. Major Pleistocene edifice collapse produced a debris avalanche and lahar that traveled north down the Hood River valley and crossed the Columbia River. The glacially eroded volcano has had at least four major eruptive periods during the past 15,000 years. The last three occurred within the past 1800 years from vents high on the SW flank and produced deposits that were distributed primarily to the south and west along the Sandy and Zigzag rivers. The last eruptive period took place around 170-220 years ago, when growth of the Crater Rock lava dome was accompanied by pyroclastic flows and lahars down the White and Sandy rivers. The Sandy River lahar deposits extended to the west as far as the Columbia River and were observed by members of the 1804-1805 Lewis and Clark expedition within a few years of their emplacement. Minor 19th-century eruptions were witnessed from Portland.