Mark Darienzo - Academia.edu (original) (raw)

Papers by Mark Darienzo

Published bimonthly by the Oregon Department of GeQlogy and Minerallodustries (Volumes 1 through ... more Published bimonthly by the Oregon Department of GeQlogy and Minerallodustries (Volumes 1 through 40 were entitled The Ore Bin).

Journal of Coastal Research, 2013

Representative shallow cores (1-2-m depth) from the Waatch Valley (n ¼ 10) and from Neah Bay back... more Representative shallow cores (1-2-m depth) from the Waatch Valley (n ¼ 10) and from Neah Bay back-barrier wetlands (n ¼ 7) record four coseismic subsidence events and associated paleotsunami inundations during the last 1300 years in the North Central Cascadia Margin. Three of the subsidence events (SUB1, SUB2b, and SUB3) correlate to reported great earthquakes dated at AD 1700, about 1.1 ka, and about 1.3 ka. An additional subsidence horizon (SUB2a), which is newly discovered in the study area, might correlate to a widely reported paleotsunami inundation, dated between 0.7 and 0.9 ka in the study region. The magnitudes of paleosubsidence in the Waatch Valley are modest (about 0.5À1.0 m), as based on macofossil evidence of abrupt wetland burial. Paleotsunami origins of the four landward thinning sand sheets are confirmed by the presence of ocean diatom taxa and beach sand grains. Long wave run-up in the low-gradient Waatch floodplain ranged from 2.5 to 4.5 km up-valley distance from the present tidal inlet shoreline. Paleotsunami overtopping of the Neah Bay barrier ridge (6-8-m elevation North American Vertical Datum of 1988 [NAVD88]) provides the first estimates of paleotsunami minimum run-up height at the entrance to the Juan de Fuca Strait.

Open-File Report, 1991

Late Holocene sequences of buried peaty horizons, 2 to 10 in number, from marsh cut banks and fro... more Late Holocene sequences of buried peaty horizons, 2 to 10 in number, from marsh cut banks and from 19 salt marsh core sites in Alsea Bay, Oregon have been analyzed for composition, lateral correlation and age. These analyses are used to discriminate between different mechanisms of marsh submergence and burial, including river flooding, ocean setup , barrier spit breaching and coseismic subsidence. System wide marsh responses to abrupt, but persistent, submergence events in Alsea Bay are demonstrated by (1) lateral correlation of key peaty horizons over distances of up to 3 km, (2) consistent vertical trends in peaty burial units, generally including increasing organics and decreasing sand content upunit, and (3) close association of anomalous (sand-rich) tsunami deposits immediately overlying, buried peaty horizons. The study results rule out marsh burial by catastrophic climatic or oceanographic processes, and argue for episodic coastal submergence forced by abrupt coseismic subsidence in an active subduction zone. An average recurrence interval of 500 yr is estimated from 8 repeat intervals of coseismic subsidence between 4,510 and 480 RCYBP. By comparison, an average recurrence interval of 340 yr is estimated from the three most recent repeat intervals of coseismic subsidence between 1,490 and 480 RCYBP. Recurrence intervals between successive burial events are found to range from 250 to 1,370 years (uncalibrated radiocarbon years). The average minimum magnitude of vertical subsidence in Alsea Bay (0.5-1 m) at 44.4° N latitude is substantially less than that reported for Netarts Bay (1-1.5 m) at 45.4°, but more than that for Siuslaw Bay (0-0.5 m) at 44.0°. This trend in average coseismic subsidence implies a coastline closure with a zero isobase south of 44° N, and a 90 km distance between the zero isobase and the trench off central Oregon. Finally, a high correspondence between marsh subsidence and tsunami (sand layer) deposition is observed in Alsea Bay, even though the estimated amount of local coastal subsidence (0.5-1 m) is small.

Four estuaries (Necanicum, Nestucca, Siletz, and Yaquina), located on the northern Oregon COBBt a... more Four estuaries (Necanicum, Nestucca, Siletz, and Yaquina), located on the northern Oregon COBBt and within the central Cascadia subduction zone, record evidence of peats that were buried during coseismic subsidence and postseismic deposition of tsunami sands and estuarine sediments as a result of great subduction zone earthquakes (magnitudes greater than 8). The identification of great earthquakes in these estuaries complements similar evidence in other estuaries in northern Oregon. The same number of burial events (6) are found within the top 3 m and within approximately the last 2,800 14C years in at least seven estuaries on the northern Oregon coast. Unequivocal evidence for great earthquakes could not be provided for all buried peats identified in the stratigraphic record. The stratigraphic records of buried peats vary because of differences in morphology, sediment supply, wetland surface elevations, and preservation potential within and among estuaries. However, consistent records of abrupt subsidence and corresponding tsunami deposition are observed in each of the estuaries, confirming the potential for great earthquakes along the northern Oregon coast. Wetland sites that record the best history of earthquakes are those with 1) elevations that are low enough to document rapid environmental changes that are easily recognized in the stratigraphic record, 2) an adequate sediment supply that allows wetlands to redevelop after coseismic subsidence, 3) locations that are in the path of sand-laden tsunami surges, and 4) locations that are away from migrating channels which erode the geologic record.

Earthquake Spectra, 1995

Earthquakes in the past few thousand years have left signs of land-level change, tsunamis, and sh... more Earthquakes in the past few thousand years have left signs of land-level change, tsunamis, and shaking along the Pacific coast at the Cascadia subduction zone. Sudden lowering of land accounts for many of the buried marsh and forest soils at estuaries between southern British Columbia and northern California. Sand layers on some of these soils imply that tsunamis were triggered by some of the events that lowered the land. Liquefaction features show that inland shaking accompanied sudden coastal subsidence at the Washington-Oregon border about 300 years ago. The combined evidence for subsidence, tsunamis, and shaking shows that earthquakes of magnitude 8 or larger have occurred on the boundary between the overriding North America plate and the downgoing Juan de Fuca and Gorda plates. Intervals between the earthquakes are poorly known because of uncertainties about the number and ages of the earthquakes. Current estimates for individual intervals at specific coastal sites range from a...

Eight small littoral cells ranging from 5-60 km in length have been surveyed by beach profiling a... more Eight small littoral cells ranging from 5-60 km in length have been surveyed by beach profiling and seismic refraction to establish active beach sand volumes in the Pacific Northwest region. Regional tectonic uplift in this convergent margin setting has produced shallow wave-cut platforms (1-3 m depth subsurface) under beaches of variable width (150-450 m). Thicker beach deposits are located in barrier spits and over wave-cut platforms lowered by local erosion and tectonic down warping. Cross-section areas of beach transects range from 15 to 3,425 m 2 , while cross-section areas above MHHW (an indicator of shoreline erosional susceptibility) range from 0 to 528 m 2 . Maximum MHHW cross-section areas south of bounding headlands and jetty structures in six of the eight cells suggest a small, net northward littoral transport in the study region. Total cell sand volumes range from 0.6 × 10 6 to 90 × 10 6 m 3 while longshore normalized, total sand volumes (cubic meters per meter shorelin...

Similarities in number, depth, sequence stratigraphy, and radiocarbon ages characterize buried pe... more Similarities in number, depth, sequence stratigraphy, and radiocarbon ages characterize buried peats of seven estuaries along 175 Ian of the northern Oregon coast. We use these peats to infer the extent of earthquake-induced subsidence, earthquake magnitudes, and average recurrence intervals for late Holocene earthquakes at the Cascadia Subduction Zone. Synchroneity of earthquake-induced subsidence from Alsea Bay to the Necanicum River over a coastal distance of 175 Ian is inferred most confidently for the most recent (first) event and the third through sixth events. In contrast, earthquake-induced subsidence for the second event was lacking in at least three of the seven estuaries. However, tsunamis generated by the second event deposited sands in the unsubsided estuaries. Therefore, the second event is also considered synchronous between Alsea and Necanicum. A segment boundary between Yaquina and Netarts is inferred for the second event. From these fmdings of synchroneity, we esti...

In this report, we estimate amounts of coseismic subsidence at the Cascadia subduction zone (CSZ)... more In this report, we estimate amounts of coseismic subsidence at the Cascadia subduction zone (CSZ), based largely on plant macrofossil data. Paleosubsidence can be estimated to ±0.5 m on the basis of relative peat development and diagnostic fossil assemblages. Three regional data sets document the spatial and temporal variability of episodic coseismic subsidence at the Cascadia margin. The first data set includes two different types of paleosubmergence records in coastal Oregon. In northern Oregon all coastal wetlands with peaty deposits extending to at least 1.5 m depth record episodic subsidence. Coastal localities in central and southern Oregon show either episodic subsidence or continuous submergence. The second data set comprises paleosubsidence estimates for the last great Cascadia earthquake (about A.D. 1700) from Vancouver Island, Washington, Oregon, and northernmost California. Coseismic subsidence ranges from a maximum of 2±0.5 m in southwest Washington, to generally 1±0.5 m in northern Oregon and western Vancouver Island, to 0±0.5 m in central Oregon. Paleosubsidence from this event is variable (0-1 m) over small distances (several kilometers) in large bays of southern Oregon and northernmost California. Inland sites from Vancouver Island and the Columbia River constrain the landward reach of regional paleosubsidence from this latest great earthquake. The third data set includes subsidence estimates from older earthquakes between 300-3,500 years ago. Up to five earthquake events are inferred at nine bays in Washington and Oregon. The long-term paleosubsidence records at most of the localities are characterized by significant variability between events. The range of variation between detectable events shows a regional trend, with the largest variation (0±0.5-2±0.5 m) occurring in southwest Washington and the smallest variation (0±0.5 m) occurring on the central Oregon coast. The study results provide constraints for evaluating post-subsidence shoreline erosion and coastal flooding in the CSZ. They are also of use in helping to test fault dislocation models and associated tsunami excitation parameters.

SUMMARY Broad pocket beaches, low marine terraces, and numerous small estuaries are characteristi... more SUMMARY Broad pocket beaches, low marine terraces, and numerous small estuaries are characteristic features of the northern Oregon coast, the middle part of the Cascadia coastline that extends from British Columbia to northern California. Like the middle child, the northern Oregon coast provides the link between the northern and southern ends of the Cascadia margin. Perhaps less dramatic in relief but not in beauty, this central Cascadia coastline differs significantly from the jagged coastlines of northern Washington and southern Oregon! northern California. The apparent geologic quiescence of the north ern Oregon coast does not reflect the catastrophic earthquakes that have struck the region in recent prehistoric time. On this field trip, we explore the northern half of the Oregon coastline for geologic evidence of subduction zone seismicity. Such evidence includes multiple events of abrupt coastal subsidence, tsunami inundation, and shaking-induced liquefaction of unconsoli dat...

Oregon Geology is designed to reach a wide spectrum of readers interested in the geology and mine... more Oregon Geology is designed to reach a wide spectrum of readers interested in the geology and mineral industry of Oregon. Manuscript contributions are invited on both technical and general-interest subjects relating to Oregon geology. Two copies of the manuscript should be submitted, typed double-spaced throughout (including references) and on one side of the paper only. If manuscript was prepared on common wordprocessing equipment (IBM compatible or Macintosh), a file copy on diskette should be submitted in place of one paper copy (from Macintosh systems, 3.5-inch high-<lensity diskette only). Graphic illustrations should be camera-ready; photographs should be black-and-white glossies. All figures should be clearly marked, and all figure captions should be together on a separate sheet of paper. The style to be followed is generally that of U.S. Geological Survey publications. (See the USGS manual Suggestions to Authors, 7th ed., 1991, or recent issues of Oregon Geology.) The bibliography should be limited to references cited. Authors are responsible for the accuracy of the bibliographic references. Names of reviewers should be included in the acknowledgments. Authors will receive 20 complimentary copies of the issue containing their contribution. Manuscripts, news, notices, and meeting announcements should be sent to Beverly F. VOgl, Publications Manager, at the Portland office of the Oregon Department of Geology and Mineral Industries. Cover illustration Isoseismal maps for significant earthquakes in 1961 near Portland. "X" indicates additional epicentral locations as described in text. Related article about historical earthquakes in and around Portland begins on page 116. OIL AND GAS NEWS Drilling continues at Mist Gas Field At the Mist Gas Field in Columbia County, Nahama and Weagant Energy Company of Bakersfield, California, continues the multiple-well drilling program that began during May. Longview Fibre 12A-33-75 (TD 2,475 ft) was completed as a successful gas well; Longview Fibre 12B-35-65 (TD 3,727 ft) is currently suspended; CFW 41-35-75 (TD 3,331 ft), Adams 31-34-75 RD (TD 3,419 ft), and CC 41-36-75 (TD 1,792 ft) were plugged and abandoned; CC 22B-19-65 is currently suspended at a total depth of 2,940 ft; and at LF 31-36-65, drilling operations are underway. NWPA symposium approaching fast Registration materials are still available for the Northwest Petroleum Association (NWPA) 10th annual symposium, which will be held September 26-28,1993, at the Inn of the Seventh Mountain in Bend, Oregon. The symposium will include a field trip to the Newberry National Volcanic Monument. For further information, contact the NWPA,

Natural Hazards, 2005

The National Tsunami Hazard Mitigation Program (NTHMP) Steering Committee consists of representat... more The National Tsunami Hazard Mitigation Program (NTHMP) Steering Committee consists of representatives from the National Oceanic and Atmospheric Administration (NOAA), the Federal Emergency Management Agency (FEMA), the U.S. Geological Survey (USGS), and the states of Alaska, California, Hawaii, Oregon, and Washington. The program addresses three major components: hazard assessment, warning guidance, and mitigation. The first two components, hazard assessment and warning guidance, are led by physical scientists who, using research and modeling methods, develop products that allow communities to identify their tsunami hazard areas and receive more accurate and timely warning information. The third component, mitigation, is led by the emergency managers who use their experience and networks to translate science and technology into user-friendly planning and education products. Mitigation activities focus on assisting federal, state, and local officials who must plan for and respond to disasters, and for the public that is deeply affected by the impacts of both the disaster and the pre-event planning efforts. The division between the three components softened as NTHMP scientists and emergency managers worked together to develop the best possible products for the users given the best available science, technology, and planning methods using available funds.

Tectonics, 1990

TECTONICS, VOL.9, N0.1, PAGES 1-22, FEBRUARY 1990 EPISODIC TECTONIC SUBSIDENCE OF LATE HOLOCENE S... more TECTONICS, VOL.9, N0.1, PAGES 1-22, FEBRUARY 1990 EPISODIC TECTONIC SUBSIDENCE OF LATE HOLOCENE SALT MARSHES, NORTHERN OREGON CENTRAL CASCADIA MARGIN Mark E. Darienzo and Curt D. Peterson Geology Department, Portland State University, ...

Natural Hazards, 2005

Coastal areas are warned of a tsunami by natural phenomena and man-made warning systems. Earthqua... more Coastal areas are warned of a tsunami by natural phenomena and man-made warning systems. Earthquake shaking and/or unusual water conditions, such as rapid changes in water level, are natural phenomena that warn coastal areas of a local tsunami that will ...

Natural Hazards, 2005

FRANK I. GONZA´ LEZ1?, VASILY V. TITOV2, HAROLD O. MOFJELD1, ANGIE J. VENTURATO2, R. SCOTT SIMMON... more FRANK I. GONZA´ LEZ1?, VASILY V. TITOV2, HAROLD O. MOFJELD1, ANGIE J. VENTURATO2, R. SCOTT SIMMONS3, ROGER HANSEN4, RODNEY COMBELLICK5, RICHARD K. EISNER6, DON F. HOIRUP7, BRIAN S. YANAGI8, STERLING YONG9, MARK ...

Journal of Coastal Research, 2013

Open-File Report, 1991

Earthquake Spectra, 1995

Natural Hazards, 2005

Tectonics, 1990

Natural Hazards, 2005