Totschunda Fault Research Articles

Intermediate-Term Declines in Seismicity at Mt. Wrangell and Mt. Veniaminof Volcanoes, Alaska, following the 3 November 2002 Mw 7.9 Denali Fault Earthquake

The M w 7.9 Denali fault earthquake ruptured segments of the Susitna Glacier, Denali, and Totschunda faults in central Alaska, providing a unique opportunity to look for intermediate-term (weeks to months) responses of active volcanoes to shaking from a large earthquake. The Alaska Volcano Observatory (avo) monitors 24 volcanoes with seismograph networks. We examined one station per volcano. Digitally-filtered data for the period four weeks before to four weeks after the mainshock were plotted at a standard scale. Mt. Wrangell, the closest volcano to the epicenter (247 km), had a background rate of 16 events/day. For the following 30 days, however, its seismicity rate dropped by 50%. Mt. Veniaminof (1400 km from the epicenter) had a rate of 8 seismic events/day, but suffered a drop in seismicity by 80% after the maishock; this may have lasted for 15 days. The seismicity at both volcanoes is dominated by long-period seismic events. With the exception of Martin and Novarupta volcanoes, the other 20 volcanoes showed no changes in seismicity attributable to the Denali fault earthquake. We conclude that the changes in seismicity observed are real, and are related to the Denali fault earthquake. These seismicity drops are in strong contrast to cases of short-term triggered seismicity increases observed at other volcanic systems such as Martin-Novarupta, Mt. Rainier, Yellowstone, Mammoth Mountain, and The Geysers, Coso and Cerro Prieto (Mexico) geothermal fields. This suggests that fundamentally different mechanisms may be acting to modify seismicity at volcanoes.

The 2002 Denali Fault and 2001 Kunlun Fault Earthquakes: Complex Rupture Processes of Two Large Strike-Slip Events

We studied the source processes of two large continental earthquakes, the 3 November 2002 Denali fault earthquake and the 14 November 2001 Kunlun fault earthquake, associated with strike-slip faulting along ancient sutures. We inverted teleseismic P waveforms using a pulse-stripping method for multiple time windows with different focal mechanisms and derived composite source models. According to our results, the 2002 Denali fault earthquake began with initial thrusting ( M w 7.3) along a 40-km-long segment of the north-northwest-dipping Susitna Glacier fault and later ruptured a 300-km-long segment along the Denali and Totschunda faults with a right-lateral strike-slip mechanism ( M w 7.7). In contrast, the 2001 Kunlun fault earthquake nucleated near an extensional step-over with a subevent pair consisting of 30-km-long strike-slip ( M w 6.9) event and 40-km-long normal ( M w 6.8) faulting event and later ruptured a 350-km-long segment along the Kunlun fault with a left-lateral strike-slip mechanism ( M w 7.7). Both earthquakes propagated primarily unilaterally to the east and released most of their energy along slip patches (asperities) far from the hypocenter locations. We find that both the Denali fault and Kunlun fault earthquakes had high-average rupture velocities of 3.2 km/sec and 3.4 km/sec, respectively. We also compared the source properties of these two earthquakes with other strike-slip earthquakes. For scaling purposes, large strike-slip earthquakes were classified as interplate, oceanic intraplate, or continental intraplate events. By using this classification the Denali fault and Kunlun fault earthquakes have an interplate signature that suggests overall weak faulting.

Preface to the Issue Dedicated to the 2002 Denali Fault Earthquake Sequence

On 3 November 2002, a M w 7.9 earthquake, the largest continental strike-slip earthquake in North America since the 1857 Fort Tejon, California, event, occurred in central Alaska. The earthquake began with reverse faulting on a ∼40-km extent of the previously unknown Susitna Glacier fault, but rupture transferred eastward to the right-lateral Denali fault and continued for over 200 km, finally transferring to rupture ∼70 km of the Totschunda fault. This large, complex event we term the Denali fault earthquake (dfe), after the major crustal fault that carried most of the displacement. The initiation of the rupture, the Susitna Glacier fault, is in a remote region of central Alaska that under normal circumstances is sparsely instrumented. On 23 October of that year, however, a large earthquake of M w 6.7, referred to as the Nenana Mountain earthquake (nme), occurred only 22 km to the west of the dfe epicenter. The nme, in hindsight recognized as a foreshock to the dfe, prompted deployment of a temporary network by the Alaska Earthquake Information Center (aeic). Hence, the area was under significantly enhanced seismic surveillance at the time of the dfe, 10 days later, which was further augmented by the addition of 19 more stations following the dfe mainshock. As a result, high-quality data were available in the near field, providing enhanced coverage for aftershock activity from the Susitna Glacier fault initiation point, along the Denali fault as far as the western portion of the Totschunda fault, to augment regional and teleseismic data for this sequence. As the rupture proceeded eastward, the Richardson Highway, one of the two north–south roads connecting the central and southern parts of the state, was disrupted where it crosses the Denali fault trace. Also significantly displaced was the Trans-Alaska Pipeline, operated by the Alyeska Pipeline …

Seismotectonics of the Central Denali Fault, Alaska, and the 2002 Denali Fault Earthquake Sequence

In this article we analyze the spatial and temporal variations in the seismicity and stress state within the central Denali fault system, Alaska, before and during the 2002 Denali fault earthquake sequence. Seismicity for 30 years prior to the 2002 earthquake sequence along the Denali fault was very light, with an average of four events with magnitude M L ≥ 3 per year. We observe a significant increase in the seismicity rate prior to the M W 7.9 event of 3 November 2002 within its epicentral region, starting about 8 months before its occurrence. The majority of the aftershocks of the M W 7.9 event are located within the upper 11 km of the crust and form several persistent clusters with a few aseismic patches along the ruptured fault. The most active aftershock source is associated with the epicentral region of the earthquake. The overall b -value of the aftershock sequence is 0.96 with the highest b -values within the epicentral region. We estimate that it will take 14 years for the seismicity rate to drop back to the background level. The stress regime across the region varies in space and time. The inferred stress regime prior to the 2002 sequence is predominately strike slip. Along the central part of the rupture zone, the orientations of the least- and intermediate-stress axes are reversed after the 2002 earthquake sequence. The maximum compressive stresses along the Denali fault rotate clockwise by up to 35°; the greatest rotations occur in the area of the rupture step-over from the Denali to the Totschunda fault. The inferred stress regime after the 2002 sequence reflects an interchanging thrusting and strike-slip faulting along the ruptured fault. The thrust faulting is concentrated in the epicentral region of the M W 7.9 event and along the rupture segments showing the largest surface offsets.

Surface Rupture of the 2002 Denali Fault, Alaska, Earthquake and Comparison with Other Strike-Slip Ruptures

On 3 November 2002, an M7.9 earthquake produced 340 km of surface rupture on the Denali and two related faults in Alaska. The rupture proceeded from west to east and began with a 40-km-long break on a previously unknown thrust fault. Estimates of surface slip on this thrust are 3–6 m. Next came the principal surface break along ∼218 km of the Denali fault. Right-lateral offsets averaged around 5 m and increased eastward to a maximum of nearly 9 m. The fault also ruptured beneath the trans-Alaska oil pipeline, which withstood almost 6 m of lateral offset. Finally, slip turned southeastward onto the Totschunda fault. Right-lateral offsets are up to 3 m, and the surface rupture is about 76 km long. This three-part rupture ranks among the longest strike-slip events of the past two centuries. The earthquake is typical when compared to other large earthquakes on major intracontinental strike-slip faults.

Strong-Motion Records of the 2002 Denali Fault, Alaska, Earthquake

The MW 7.9 Denali Fault earthquake on 3 November 2002 ruptured a 340-km section along the Susitna Glacier, Denali, and Totschunda faults in central Alaska. The earthquake was digitally recorded at more than 55 strong-motion sites throughout the state at distances up to 280 km from the fault rupture. The site closest to the fault, Trans-Alaska Pipeline Pump Station 10, is located about 3 km north of the surface rupture, where the observed maximum horizontal peak ground acceleration was about 0.35 g. The peak horizontal accelerations observed at the sites closest to the fault rupture were considerably smaller than those yielded by the ground-motion prediction equations. Although the earthquake provided a valuable set of strong-motion data, an important opportunity was missed to capture near-field recordings from such a major strike-slip event. A concerted national effort is needed to prioritize the instrumentation of faults that are likely locations of future great earthquakes.

Seismological Aspects of the 2002 Denali Fault, Alaska, Earthquake

The M7.9 Denali fault earthquake occurred on 3 November 2002 with an epicenter located 135 km south of Fairbanks and 283 km north of Anchorage. This epicenter is 22–25 km east of the M6.7 Nenana Mountain earthquake that occurred eleven days earlier, October 23, awakening some inhabitants of central Alaska at about 3:30 that morning. Like most earthquakes of its size, the M7.9 earthquake was a complex event. The rupture began with vertical slip along a 40-km segment of the previously unrecognized Susitna Glacier thrust fault, which is connected to the Denali fault. The rupture continued with right-lateral horizontal slip along the main trace of the Denali fault. It eventually split off the Denali fault onto the more southeast-trending Totschunda fault. The total rupture length was 330–340 kilometers, with at least three areas of high slip, or high energy release.

Kinematic and dynamic rupture models of the November 3, 2002 Mw7.9 Denali, Alaska, earthquake

Regional seismic waveforms, continuous and campaign‐mode GPS data, and surface slip measurements were used to obtain a kinematic model of the rupture process of the November 3, 2002 Mw 7.9 Denali, Alaska, earthquake. The event initiated as a Mw 7.0 reverse slip event on the north‐dipping Susitna Glacier fault with subsequent right‐lateral slip distributed over approximately 300 km of the Denali fault system. Near‐shear rupture velocity is inferred from the kinematic modeling. The average and maximum slips were found to be 2.14 m and 10.3 m. Static stress drop varies from 1.3 to 5.0 MPa over the 5‐segment fault model. Dynamic modeling shows the rupture propagated along the Susitna Glacier and Denali faults, then transferred to the Totschunda fault before stopping, largely due to the Totschunda's more favorable orientation with respect to the regional stress field.

Inverse Kinematic and Forward Dynamic Models of the 2002 Denali Fault Earthquake, Alaska

We perform inverse kinematic and forward dynamic models of the M 7.9 2002 Denali fault, Alaska, earthquake to shed light on the rupture process and dynamics of this event, which took place on a geometrically complex fault system in central Alaska. We use a combination of local seismic and Global Positioning System (gps) data for our kinematic inversion and find that the slip distribution of this event is characterized by three major asperities on the Denali fault. The rupture nucleated on the Susitna Glacier thrust fault, and after a pause, propagated onto the strike-slip Denali fault. Approximately 216 km to the east, the rupture abandoned the Denali fault in favor of the more southwesterly directed Totschunda fault. Three-dimensional dynamic models of this event indicate that the abandonment of the Denali fault for the Totschunda fault can be explained by the Totschunda fault’s more favorable orientation with respect to the local stress field. However, a uniform tectonic stress field cannot explain the complex slip pattern in this event. We also find that our dynamic models predict discontinuous rupture from the Denali to Totschunda fault segments. Such discontinuous rupture helps to qualitatively improve our kinematic inverse models. Two principal implications of our study are (1) a combination of inverse and forward modeling can bring insight into earthquake processes that are not possible with either technique alone, and (2) the stress field on geometrically complex fault systems is most likely not due to a uniform tectonic stress field that is resolved onto fault segments of different orientations; rather, other forms of stress heterogeneity must be invoked to explain the observed slip patterns.

Surface Rupture and Slip Distribution of the Denali and Totschunda Faults in the 3 November 2002 M 7.9 Earthquake, Alaska

The 3 November 2002 Denali fault, Alaska, earthquake resulted in 341 km of surface rupture on the Susitna Glacier, Denali, and Totschunda faults. The rupture proceeded from west to east and began with a 48-km-long break on the previously unknown Susitna Glacier thrust fault. Slip on this thrust averaged about 4 m (Crone et al. , 2004). Next came the principal surface break, along 226 km of the Denali fault, with average right-lateral offsets of 4.5–5.1 m and a maximum offset of 8.8 m near its eastern end. The Denali fault trace is commonly left stepping and north side up. About 99 km of the fault ruptured through glacier ice, where the trace orientation was commonly influenced by local ice fabric. Finally, slip transferred southeastward onto the Totschunda fault and continued for another 66 km where dextral offsets average 1.6–1.8 m. The transition from the Denali fault to the Totschunda fault occurs over a complex 25-km-long transfer zone of right-slip and normal fault traces. Three methods of calculating average surface slip all yield a moment magnitude of M w 7.8, in very good agreement with the seismologically determined magnitude of M 7.9. A comparison of strong-motion inversions for moment release with our slip distribution shows they have a similar pattern. The locations of the two largest pulses of moment release correlate with the locations of increasing steps in the average values of observed slip. This suggests that slip-distribution data can be used to infer moment release along other active fault traces. Online Material : Descriptions and photographs of localities with offset measurements.

Stress Transfer to the Denali and Other Regional Faults from the M 9.2 Alaska Earthquake of 1964

Stress transfer from the great 1964 Prince William Sound earthquake is modeled on the Denali fault, including the Denali-Totschunda fault segments that ruptured in 2002, and on other regional fault systems where M 7.5 and larger earth- quakes have occurred since 1900. The results indicate that analysis of Coulomb stress transfer from the dominant earthquake in a region is a potentially powerful tool in assessing time-varying earthquake hazard. Modeled Coulomb stress increases on the northern Denali and Totschunda faults from the great 1964 earthquake coincide with zones that ruptured in the 2002 Denali fault earthquake, although stress on the Susitna Glacier thrust plane, where the 2002 event initiated, was decreased. A southeasterly- trending Coulomb stress transect along the right-lateral Totschunda-Fairweather- Queen Charlotte trend shows stress transfer from the 1964 event advancing slip on the Totschunda, Fairweather, and Queen Charlotte segments, including the southern Fairweather segment that ruptured in 1972. Stress transfer retarding right-lateral strike slip was observed from the southern part of the Totschunda fault to the northern end of the Fairweather fault (1958 rupture). This region encompasses a gap with shallow thrust faulting but with little evidence of strike-slip faulting connecting the segments to the northwest and southeast. Stress transfer toward failure was computed on the north-south trending right-lateral strike-slip faults in the Gulf of Alaska that ruptured in 1987 and 1988, with inhibitory stress changes at the northern end of the northernmost (1987) rupture. The northern Denali and Totschunda faults, including the zones that ruptured in the 2002 earthquakes, follow very closely (within 3%), for about 90, an arc of a circle of radius 375 km. The center of this circle is within a few kilometers of the intersection at depth of the Patton Bay fault with the Alaskan megathrust. This inferred asperity edge may be the pole of counterclockwise rotation of the block south of the Denali fault. These observations suggest that the asperity and its recurrent rupture in great earthquakes as in 1964 may have influenced the tectonics of the region during the later stages of evolution of the Denali strike-slip fault system.

Rupture Process of the M 7.9 Denali Fault, Alaska, Earthquake: Subevents, Directivity, and Scaling of High-Frequency Ground Motions

Displacement waveforms and high-frequency acceleration envelopes from stations at distances of 3–300 km were inverted to determine the source process of the M 7.9 Denali fault earthquake. Fitting the initial portion of the displacement waveforms indicates that the earthquake started with an oblique thrust subevent (subevent #1) with an east–west-striking, north-dipping nodal plane consistent with the observed surface rupture on the Susitna Glacier fault. Inversion of the remainder of the waveforms (0.02–0.5 Hz) for moment release along the Denali and Totschunda faults shows that rupture proceeded eastward on the Denali fault, with two strike-slip subevents (numbers 2 and 3) centered about 90 and 210 km east of the hypocenter. Subevent 2 was located across from the station at ps10 (Trans-Alaska Pipeline Pump Station #10) and was very localized in space and time. Subevent 3 extended from 160 to 230 km east of the hypocenter and had the largest moment of the subevents. Based on the timing between subevent 2 and the east end of subevent 3, an average rupture velocity of 3.5 km/sec, close to the shear wave velocity at the average rupture depth, was found. However, the portion of the rupture 130–220 km east of the epicenter appears to have an effective rupture velocity of about 5.0 km/sec, which is supershear. These two subevents correspond approximately to areas of large surface offsets observed after the earthquake. Using waveforms of the M 6.7 Nenana Mountain earthquake as empirical Green’s functions, the high-frequency (1–10 Hz) envelopes of the M 7.9 earthquake were inverted to determine the location of high-frequency energy release along the faults. The initial thrust subevent produced the largest high-frequency energy release per unit fault length. The high-frequency envelopes and acceleration spectra (>0.5 Hz) of the M 7.9 earthquake can be simulated by chaining together rupture zones of the M 6.7 earthquake over distances from 30 to 180 km east of the hypocenter. However, the inversion indicates that there was relatively little high-frequency energy generated along the 60-km portion of the Totschunda fault on the east end of the rupture.

Aftershock Sequence of the Mw 7.9 Denali Fault, Alaska, Earthquake of 3 November 2002 from Regional Seismic Network Data

The largest inland earthquake in North America in almost 150 years struck Alaska on 3 November 2002. It ruptured three different faults, with a total rupture length of ∼330 km. It started on the previously unrecognized Susitna Glacier Thrust Fault, a splay fault south of the McKinley strand of the Denali Fault system (DFS). Then the rupture transferred onto the main strand of the DFS and continued as a right-lateral strike-slip event for ∼220 km until it reached the Totschunda Fault, near 143°W longitude. At that point, it right-stepped onto the more southeasterly trending Totschunda Fault and stopped after rupturing nearly 70 km of it. A team of geologists surveyed the total length of the ruptured faults and reported maximum vertical offsets on the Susitna Glacier Thrust of 4 m and maximum horizontal offsets of 8.8 m west of the Denali and Totschunda Fault junction (Eberhart-Phillips et al., 2003). The estimated magnitude of this earthquake ranges from mb 7.0 to MW 7.9 to MS 8.5. While the fault rupture lasted for approximately 100 sec from its initiation to the arrest, its distal effects were felt for many days. The hardest hit population centers were the villages of Mentasta and Northway, at the eastern end of the rupture zone. This event caused significant damage to the transportation systems in central Alaska. The Trans-Alaska Pipeline suffered some damage, but no oil spills occurred. Multiple landslides and rock avalanches occurred in the Alaska Range, with the largest slide on the Black Rapids Glacier (Truffer et al., 2002). The Denali Fault event was felt as far away as Washington state (Barberopoulou et al., 2003) and caused seiches in pools and lakes as far away as Texas and Louisiana (Farrel et al., 2002). There were reports of triggered seismicity in volcanic and …

Deformation of the 2002 Denali Fault Earthquakes, mapped by Radarsat‐1 interferometry

The magnitude 7.9 earthquake that struck central Alaska on 3 November 2002 was the largest strike‐slip earthquake in North America for more than 150 years. The earthquake ruptured about 340 km of the Denali Fault system with observed right‐lateral offsets of up to 9 m [Eberhart‐Phillips et al., 2003] (Figure l). The rupture initiated with slip on a previously unknown thrust fault, the 40‐km‐long Susitna Glacier Fault. The rupture propagated eastward for about 220 km along the right‐lateral Denali Fault where right‐lateral slip averaged ˜5 m, before stepping southeastward onto the Totschunda Fault for about 70 km, with offsets as large as 2 m. The 3 November earthquake was preceded by a magnitude 6.7 shock on 23 October—the Nenana Mountain Earthquake—which was located about 25 km to the west of the 3 November earthquake.

Change in stress directions along the central Denali fault, Alaska after the 2002 earthquake sequence

On the basis of earthquake focal mechanisms, the state of stress along the central Denali fault, Alaska system changed after the 2002 earthquake sequence. Before the earthquake sequence, the maximum stress (σ1) was at a 60° angle with the Denali fault west of the point of its maximum curvature, fault‐normal between the fault apex and the Totschunda strand, and at 50° with respect to the Totschunda fault. In the epicentral region, the post‐event σ1 has rotated counter‐clockwise. Along the rest of the rupture zone the sense of rotation is clockwise. The σ1 direction became nearly fault‐normal along the Totschunda strand. Along the central part of the rupture, σ1 is over‐rotated with σ3 being nearly vertical, promoting reverse aftershocks. This could be an indication of dynamic overshoot.

Coseismic slip distribution of the 2002 MW7.9 Denali fault earthquake, Alaska, determined from GPS measurements

On 3 November 2002 an MW7.9 earthquake occurred in central Alaska. The earthquake ruptured portions of the Susitna Glacier, Denali, and Totschunda faults. Inversion of the GPS‐measured displacement field indicates that the event was dominated by a complex, right‐lateral strike‐slip rupture along the Denali fault. GPS sites closest to the epicenter show the effect of thrust motion on the Susitna Glacier fault. The preferred coseismic slip model, with MW7.8, indicates relatively low slip on the western part of the rupture and high slip from about 60 km east of the hypocenter extending to the junction of the Denali and Totschunda faults. We find mostly shallow slip from the surface to 15 km depth, but the inversion suggests one large deep slip patch about 110 km east of the hypocenter. Our model predicts surface slip in good agreement with surface geological observations, where model resolution is good.

Static stress transfer during the 2002 Nenana Mountain-Denali Fault, Alaska, earthquake sequence

[1] On 23 October 2002, the Mw 6.7 Nenana Mountain earthquake occurred in central Alaska. It was followed on 3 November 2002 by the Mw 7.9 Denali Fault mainshock, the largest strike-slip earthquake to occur in North America during the past 150 years. We have modeled static Coulomb stress transfer effects during this sequence. We find that the Nenana Mountain foreshock transferred 30–50 kPa of Coulomb stress to the hypocentral region of the Denali Fault mainshock, encouraging its occurrence. We also find that the two main earthquakes together transferred more than 400 kPa of Coulomb stress to the Cross Creek segment of the Totschunda fault system and to the Denali fault southeast of the mainshock rupture, and up to 80 kPa to the Denali fault west of the Nenana Mountain rupture. Other major faults in the region experienced much smaller static Coulomb stress changes.

The 2002 Denali fault earthquake, Alaska: a large magnitude, slip-partitioned event.

The MW (moment magnitude) 7.9 Denali fault earthquake on 3 November 2002 was associated with 340 kilometers of surface rupture and was the largest strike-slip earthquake in North America in almost 150 years. It illuminates earthquake mechanics and hazards of large strike-slip faults. It began with thrusting on the previously unrecognized Susitna Glacier fault, continued with right-slip on the Denali fault, then took a right step and continued with right-slip on the Totschunda fault. There is good correlation between geologically observed and geophysically inferred moment release. The earthquake produced unusually strong distal effects in the rupture propagation direction, including triggered seismicity.

Alaska crustal deformation: Finite element modeling constrained by geologic and very long baseline interferometry data

We compute crustal motions in Alaska by calculating the finite element solution for an elastic spherical shell problem. The method we use allows the finite element mesh to include faults and very long baseline interferometry (VLBI) baseline rates of change. Boundary conditions include Pacific‐North American (PA‐NA) plate motions. The solution is constrained by the oblique orientation of the Fairweather‐Queen Charlotte strike‐slip faults relative to the PA‐NA relative motion direction and the oblique orientation from normal convergence of the eastern Aleutian trench fault systems, as well as strike‐slip motion along the Denali and Totschunda fault systems. We explore the effects that a range of fault slip constraints and weighting of VLBI rates of change has on the solution. This allows us to test the motion on faults, such as the Denali fault, where there are conflicting reports on its present‐day slip rate. We find a pattern of displacements which produce fault motions generally consistent with geologic observations. The motion of the continuum has the general pattern of radial movement of crust to the NE away from the Fairweather‐Queen Charlotte fault systems in SE Alaska and Canada. This pattern of crustal motion is absorbed across the Mackenzie Mountains in NW Canada, with strike‐slip motion constrained along the Denali and Tintina fault systems. In south central Alaska and the Alaska forearc oblique convergence at the eastern Aleutian trench and the strike‐slip motion of the Denali fault system produce a counterclockwise pattern of motion which is partially absorbed along the Contact and related fault systems in southern Alaska and is partially extruded into the Bering Sea and into the forearc parallel the Aleutian trench from the Alaska Peninsula westward. Rates of motion and fault slip are small in western and northern Alaska, but the motions we compute are consistent with the senses of strike‐slip motion inferred geologically along the Kaltag, Kobuk Trench, and Thompson Creek faults and with the normal faulting observed in NW Alaska near Nome. The nonrigid behavior of our finite element solution produces patterns of motion that would not have been expected from rigid block models: strike‐slip faults can exist in a continuum that has motion mostly perpendicular to their strikes, and faults can exhibit along‐strike differences in magnitudes and directions.

The upper Cenozoic White River "tillites" of southern Alaska: Subaerial slope and fan-delta deposits in a strike-slip setting

The White River tillites crop out over 8 km 2 either side of the Totschunda fault in the northern foothills of the Wrangell Mountains in southern Alaska and record glacially influenced slope and fan-delta deposition in a high-relief basin close to an active volcano between 10 and 2.7 Ma. Two measured sections, 1,200 and 450 m thick, show diamictite and conglomerates interbedded with augite andesite lavas. Facies range from massive diamictites, deposited subaerially as debris flows, to crudely stratified sandstones and conglomerates formed by sheet-flow processes on alluvial fans, and well-stratified and normally graded sandstones and conglomerates that accumulated subaqueously as turbidites; large-scale southward-dipping foresets as much as 17 m high identify a fan delta that prograded into a temporary lake. The White River succession is identified as a valley infill complex consisting of subaerial slope and lacustrine fan-delta deposits; there are no in situ primary deposits present in the succession. The component of sedimentation was limited to the supply of coarse-grained debris identified by the presence of glacially striated and faceted clasts. The White River deposits may be typical of glacial sequences preserved as isolated local basin fills in high-relief areas such as occur in convergent or strike-slip plate-margin settings. They provide only a limited and fragmentary record of paleoenvironmental changes compared to coeval glacially influenced marine rocks preserved in the Yakataga Formation (5 km thick) along the Gulf of Alaska coast.