The 2018 Palu Tsunami: Coeval Landslide and Coseismic Sources

2020 ◽  
Vol 91 (6) ◽  
pp. 3148-3160
Author(s):  
Amy L. Williamson ◽  
Diego Melgar ◽  
Xiaohua Xu ◽  
Christopher Milliner
Keyword(s):  
Survey Data ◽  
Field Survey ◽  
Tide Gauge ◽  
Hazard Analysis ◽  
Strike Slip ◽  
Coseismic Deformation ◽  
Coseismic Slip ◽  
Video Footage ◽  
Run Up ◽  
Tsunami Model

Abstract On 28 September 2018, Indonesia was struck by an MW 7.5 strike-slip earthquake. An unexpected tsunami followed, inundating nearby coastlines leading to extensive damage. Given the traditionally non-tsunamigenic mechanism, it is important to ascertain if the source of the tsunami is indeed from coseismic deformation, or something else, such as shaking induced landsliding. Here we determine the leading cause of the tsunami is a complex combination of both. We constrain the coseismic slip from the earthquake using static offsets from geodetic observations and validate the resultant “coseismic-only” tsunami to observations from tide gauge and survey data. This model alone, although fitting some localized run-up measurements, overall fails to reproduce both the timing and scale of the tsunami. We also model coastal collapses identified through rapidly acquired satellite imagery and video footage as well as explore the possibility of submarine landsliding using tsunami raytracing. The tsunami model results from the landslide sources, in conjunction with the coseismic-generated tsunami, show a greatly improved fit to both tide gauge and field survey data. Our results highlight a case of a damaging tsunami the source of which is a complex mix of coseismic deformation and landsliding. Tsunamis of this nature are difficult to provide warning for and are underrepresented in regional tsunami hazard analysis.

scholarly journals Triple junction kinematics accounts for the 2016 Mw7.8 Kaikoura earthquake rupture complexity

2019 ◽  
Vol 116 (52) ◽  
pp. 26367-26375 ◽  
Author(s):  
Xuhua Shi ◽  
Paul Tapponnier ◽  
Teng Wang ◽  
Shengji Wei ◽  
Yu Wang ◽  
...  
Keyword(s):  
New Zealand ◽  
Triple Junction ◽  
Large Scale ◽  
Strike Slip ◽  
Plate Motion ◽  
Fault System ◽  
Coseismic Deformation ◽  
Coseismic Slip ◽  
Slab Geometry ◽  
Kaikoura Earthquake

The 2016, moment magnitude (Mw) 7.8, Kaikoura earthquake generated the most complex surface ruptures ever observed. Although likely linked with kinematic changes in central New Zealand, the driving mechanisms of such complexity remain unclear. Here, we propose an interpretation accounting for the most puzzling aspects of the 2016 rupture. We examine the partitioning of plate motion and coseismic slip during the 2016 event in and around Kaikoura and the large-scale fault kinematics, volcanism, seismicity, and slab geometry in the broader Tonga–Kermadec region. We find that the plate motion partitioning near Kaikoura is comparable to the coseismic partitioning between strike-slip motion on the Kekerengu fault and subperpendicular thrusting along the offshore West–Hikurangi megathrust. Together with measured slip rates and paleoseismological results along the Hope, Kekerengu, and Wairarapa faults, this observation suggests that the West–Hikurangi thrust and Kekerengu faults bound the southernmost tip of the Tonga–Kermadec sliver plate. The narrow region, around Kaikoura, where the 3 fastest-slipping faults of New Zealand meet, thus hosts a fault–fault–trench (FFT) triple junction, which accounts for the particularly convoluted 2016 coseismic deformation. That triple junction appears to have migrated southward since the birth of the sliver plate (around 5 to 7 million years ago). This likely drove southward stepping of strike-slip shear within the Marlborough fault system and propagation of volcanism in the North Island. Hence, on a multimillennial time scale, the apparently distributed faulting across southern New Zealand may reflect classic plate-tectonic triple-junction migration rather than diffuse deformation of the continental lithosphere.

scholarly journals The 23 June 2020 Mw 7.4 La Crucecita, Oaxaca, Mexico Earthquake and Tsunami: A Rapid Response Field Survey during COVID-19 Crisis

2020 ◽  
Vol 92 (1) ◽  
pp. 26-37 ◽  
Author(s):  
María-Teresa Ramírez-Herrera ◽  
David Romero ◽  
Néstor Corona ◽  
Héctor Nava ◽  
Hamblet Torija ◽  
...  
Keyword(s):  
Field Survey ◽  
Tide Gauge ◽  
Deep Ocean ◽  
Vertical Displacement ◽  
Rapid Response ◽  
Coseismic Deformation ◽  
Response Effort ◽  
Coastal Morphology ◽  
Tsunami Inundation ◽  
Coastal Uplift

Abstract The 23 June 2020 La Crucecita earthquake occurred at 10:29 hr on the coast of Oaxaca in an Mw 7.4 megathrust event at 22.6 km depth and triggered a tsunami recorded at tide gauge stations and a Deep-ocean Assessment and Reporting of Tsunamis off the coast of Mexico. Immediately after the earthquake, a rapid response effort was coordinated by members of the Tsunami and Paleoseismology Laboratory, Universidad Nacional Autónoma de México. Despite the challenges posed by the Coronavirus disease 2019 (COVID-19) pandemic crisis, a postearthquake and post-tsunami field survey went ahead two days after the event. We describe here the details of the rapid response survey of the vertical coseismic deformation, tsunami, geologic effects, and lessons from working in the field during the COVID-19 crisis. We surveyed 44 km along the coast of Oaxaca. Because of the COVID-19 pandemic, some local communities enforced rules of confinement. We solved most of the challenges faced during this crisis by rapidly networking with local organizations prior to surveying. We assessed coseismic uplift by means of mortality caused by vertical displacement of intertidal organisms and resurveying of benchmarks, and we measured tsunami runup. Our results show coastal uplift of 0.53 m near the epicenter and decreasing farther away from it; uplift was up to 0.8 m in areas related to exposure of the coast. Of our values of coastal uplift, about 0.53 m fit well with the 0.55 m of uplift reported by tide gauge data at Huatulco. Coastal uplift and low tide at the time of the event limited the tsunami inundation and runup on the Oaxaca coast. Nevertheless, we found tsunami inundation evidence at four confined coastal sites reaching a maximum runup of 1.5 m. The enclosed morphology of these sites determined higher runup and tsunami inundation. Local coastal morphology effects are not detected in tsunami models lacking detailed bathymetry and topography. This issue needs to be addressed during tsunami hazard assessments.

Multifault complex rupture and afterslip associated with the 2018 Mw 6.4 Hualien earthquake in northeastern Taiwan

2020 ◽  
Vol 224 (1) ◽  
pp. 416-434
Author(s):  
Dezheng Zhao ◽  
Chunyan Qu ◽  
Xinjian Shan ◽  
Roland Bürgmann ◽  
Wenyu Gong ◽  
...  
Keyword(s):  
Main Shock ◽  
Near Field ◽  
Active Faults ◽  
Fault Model ◽  
Body Waves ◽  
Coseismic Deformation ◽  
Coseismic Slip ◽  
Coulomb Stress Changes ◽  
Seismic Displacement ◽  
Stress Changes

SUMMARY We investigate the coseismic and post-seismic deformation due to the 6 February 2018 Mw 6.4 Hualien earthquake to gain improved insights into the fault geometries and complex regional tectonics in this structural transition zone. We generate coseismic deformation fields using ascending and descending Sentinel-1A/B InSAR data and GPS data. Analysis of the aftershocks and InSAR measurements reveal complex multifault rupture during this event. We compare two fault model joint inversions of SAR, GPS and teleseismic body waves data to illuminate the involved seismogenic faults, coseismic slip distributions and rupture processes. Our preferred fault model suggests that both well-known active faults, the dominantly left-lateral Milun and Lingding faults, and previously unrecognized oblique-reverse west-dipping and north-dipping detachment faults, ruptured during this event. The maximum slip of ∼1.6 m occurred on the Milun fault at a depth of ∼2–5 km. We compute post-seismic displacement time series using the persistent scatterer method. The post-seismic range-change fields reveal large surface displacements mainly in the near-field of the Milun fault. Kinematic inversions constrained by cumulative InSAR displacements along two tracks indicate that the afterslip occurred on the Milun and Lingding faults and the west-dipping fault just to the east. The maximum cumulative afterslip of 0.4–0.6 m occurred along the Milun fault within ∼7 months of the main shock. The main shock-induced static Coulomb stress changes may have played an important role in driving the afterslip adjacent to coseismic high-slip zones on the Milun, Lingding and west-dipping faults.

Flow-Field Survey Data

2018 ◽  
pp. 363-373
Author(s):  
Allen E. Winkelmann
Keyword(s):  
Flow Field ◽  
Survey Data ◽  
Field Survey

scholarly journals THE 2014 MW 6.9 NORTH AEGEAN TROUGH (NAT) EARTHQUAKE: SEISMOLOGICAL AND GEODETIC EVIDENCE

2017 ◽  
Vol 50 (3) ◽  
pp. 1583
Author(s):  
V. Saltogianni ◽  
M. Gianniou ◽  
T. Taymaz ◽  
S. Yolsal-Çevikbilen ◽  
S. Stiros
Keyword(s):  
Broad Band ◽  
Strike Slip ◽  
Fault Geometry ◽  
Coseismic Slip ◽  
The North ◽  
Finite Fault Inversion ◽  
Seismological Data ◽  
Finite Fault ◽  
Slip History ◽  
North Aegean

A strong earthquake (Mw 6.9) on 24 May 2014 ruptured the North Aegean Trough (NAT) in Greece, west of the North Anatolian Fault Zone (NAFZ). In order to provide unbiased constrains of the rupture process and fault geometry of the earthquake, seismological and geodetic data were analyzed independently. First, based on teleseismic long-period P- and SH- waveforms a point-source solution yielded dominantly right-lateral strike-slip faulting mechanism. Furthermore, finite fault inversion of broad-band data revealed the slip history of the earthquake. Second, GPS slip vectors derived from 11 permanent GPS stations uniformly distributed around the meizoseismal area of the earthquake indicated significant horizontal coseismic slip. Inversion of GPS-derived displacements on the basis of Okada model and using the new TOPological INVersion (TOPINV) algorithm permitted to model a vertical strike slip fault, consistent with that derived from seismological data. Obtained results are consistent with the NAT structure and constrain well the fault geometry and the dynamics of the 2014 earthquake. The latter seems to fill a gap in seismicity along the NAT in the last 50 years, but seems not to have a direct relationship with the sequence of recent faulting farther east, along the NAFZ.

scholarly journals Multi-method observation and analysis of an impulse wave and tsunami caused by glacier calving

2015 ◽  
Vol 9 (6) ◽  
pp. 6471-6493 ◽  
Author(s):  
M. P. Lüthi ◽  
A. Vieli
Keyword(s):  
Tsunami Wave ◽  
Tide Gauge ◽  
Impulse Wave ◽  
West Greenland ◽  
Tsunami Waves ◽  
The Future ◽  
History Of ◽  
Impulse Waves ◽  
Run Up

Abstract. Glacier calving can cause violent impulse waves which, upon landfall, can lead to destructive tsunami-like waves. Here we present data acquired during a calving event from Eqip Sermia, an ocean-terminating glacier in West Greenland. During an exceptionally well documented event, the collapse of 9 × 105 m3 ice from a 200 m high ice cliff caused an impulse wave of 50 m height, traveling at a speed of 25–30 m s-1. This wave was filmed from a tour boat in 800 m distance from the calving face, and simultaneously measured with a terrestrial radar interferometer and a tide gauge. Tsunami wave run-up height on the steep opposite shore in 4 km distance was 10–15 m, destroying infrastructure and eroding old vegetation. These observations indicate that such high tsunami waves are a recent phenomenon in the history of this glacier. Analysis of the data shows that only moderately bigger tsunami waves are to be expected in the future, even under rather extreme scenarios.

An Assessment of Earthquake Scaling Relationships for Crustal Earthquakes in Indonesia

2021 ◽  
Author(s):  
Endra Gunawan
Keyword(s):  
Seismic Hazard ◽  
Active Faults ◽  
Hazard Model ◽  
Strike Slip ◽  
Coseismic Deformation ◽  
Maximum Magnitude ◽  
Scaling Relationships ◽  
Rupture Length ◽  
Scaling Relationship ◽  
Earthquake Scaling

Abstract To estimate the hazard posed by active faults, estimates of the maximum magnitude earthquake that could occur on the fault are needed. I compare previously published scaling relationships between earthquake magnitude and rupture length with data from recent earthquakes in Indonesia. I compile a total amount of 13 literatures on investigating coseismic deformation in Indonesia, which then divided into strike-slip and dip-slip earthquake cases. I demonstrate that a different scaling relationship generates different misfit compared to data. For a practical practice of making seismic hazard model in Indonesia, this research shows the suggested reference for a scaling relationship of strike-slip and dip-slip faulting regime. On a practical approach in constructing a logic tree for seismic hazard model, using different weighting between each published earthquake scaling relationship is recommended.

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