Improving Paleoseismic Earthquake Magnitude Estimates with Rupture Length Information: Application to the Puget Lowland, Washington State, U.S.A.

2020 ◽  
Author(s):  
Richard H. Styron ◽  
Brian Sherrod
Keyword(s):  
Seismic Hazard ◽  
Surface Displacement ◽  
Washington State ◽  
Bayesian Inversion ◽  
Inversion Method ◽  
Rupture Length ◽  
Vertical Fault ◽  
Seismic Hazard Map ◽  
Late Pleistocene To Holocene ◽  
Instrumental Records

ABSTRACT Both earthquake displacement and rupture length correlate with magnitude, and, therefore, observations of each from past earthquakes can be used to estimate the magnitude of those earthquakes in the absence of instrumental records. We extend the Bayesian inversion method of Biasi and Weldon (2006), which estimates paleoearthquake magnitude from displacement observations, to incorporate both rupture length and surface displacement measurements into the magnitude inversion. We then use this method on 27 late-Pleistocene to Holocene paleoearthquakes in the Puget Lowland region of Washington. Observations of (typically vertical) fault separation per event range from 0.6 to 7 m, implying net displacement per event of up to 10±4  m for the largest event. Rupture lengths are estimated to vary between the smallest contiguous mapped scarps to the full extent of the faults mapped from geology and geophysical observations. Although, a few of the ruptures may be longer than 150 km, the ruptures have a median of 53 km, indicating that earthquakes in the Puget Lowland have relatively high displacement-to-length ratios. By considering both datasets, we find that all events were between M 6.3 and 7.5, generally consistent with the expected seismicity from the U.S. Geological Survey National Seismic Hazard Map for the region. The simultaneous use of both length and displacement data in the magnitude inversion decreases both the estimated earthquake magnitudes and the uncertainty. The magnitude reduction, in particular, is due to the relatively short rupture lengths possible for Puget Lowland faults. This implies a decrease in the seismic hazard (relative to a displacement-only assessment) to a highly populated and rapidly urbanizing region.

Seismic Hazard Map for Papua Island

2018 ◽  
Vol 9 (2) ◽  
pp. 57
Author(s):  
Lalu Makrup ◽  
Arif Hariyanto ◽  
Setya Winarno
Keyword(s):  
Seismic Hazard ◽  
Hazard Map ◽  
Seismic Hazard Map

scholarly journals Estimates of European emissions of methyl chloroform using a Bayesian inversion method

2014 ◽  
Vol 14 (18) ◽  
pp. 9755-9770 ◽  
Author(s):  
M. Maione ◽  
F. Graziosi ◽  
J. Arduini ◽  
F. Furlani ◽  
U. Giostra ◽  
...  
Keyword(s):  
Point Source ◽  
High Frequency ◽  
Stratospheric Ozone ◽  
Montreal Protocol ◽  
Source Analysis ◽  
Bayesian Inversion ◽  
Inversion Method ◽  
Data Set ◽  
Methyl Chloroform

Abstract. Methyl chloroform (MCF) is a man-made chlorinated solvent contributing to the destruction of stratospheric ozone and is controlled under the "Montreal Protocol on Substances that Deplete the Ozone Layer" and its amendments, which called for its phase-out in 1996 in developed countries and 2015 in developing countries. Long-term, high-frequency observations of MCF carried out at three European sites show a constant decline in the background mixing ratios of MCF. However, we observe persistent non-negligible mixing ratio enhancements of MCF in pollution episodes, suggesting unexpectedly high ongoing emissions in Europe. In order to identify the source regions and to give an estimate of the magnitude of such emissions, we have used a Bayesian inversion method and a point source analysis, based on high-frequency long-term observations at the three European sites. The inversion identified southeastern France (SEF) as a region with enhanced MCF emissions. This estimate was confirmed by the point source analysis. We performed this analysis using an 11-year data set, from January 2002 to December 2012. Overall, emissions estimated for the European study domain decreased nearly exponentially from 1.1 Gg yr−1 in 2002 to 0.32 Gg yr−1 in 2012, of which the estimated emissions from the SEF region accounted for 0.49 Gg yr−1 in 2002 and 0.20 Gg yr−1 in 2012. The European estimates are a significant fraction of the total semi-hemisphere (30–90° N) emissions, contributing a minimum of 9.8% in 2004 and a maximum of 33.7% in 2011, of which on average 50% are from the SEF region. On the global scale, the SEF region is thus responsible for a minimum of 2.6% (in 2003) and a maximum of 10.3% (in 2009) of the global MCF emissions.

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.

BAYESIAN MAGNETOTELLURIC INVERSION USING METHYLENE BLUE STRUCTURAL PRIORS FOR IMAGING SHALLOW CONDUCTORS IN GEOTHERMAL FIELDS

Geophysics ◽  
2021 ◽  
pp. 1-66
Author(s):  
Alberto Ardid ◽  
David Dempsey ◽  
Edward Bertrand ◽  
Fabian Sepulveda ◽  
Flora Solon ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Clay Content ◽  
3D Models ◽  
Bayesian Inversion ◽  
Inversion Method ◽  
Geothermal Fields ◽  
Geological Information ◽  
Resistivity Model ◽  
Irreducible Uncertainty ◽  
Clay Cap

In geothermal exploration, magnetotelluric (MT) data and inversion models are commonly used to image shallow conductors typically associated with the presence of an electrically conductive clay cap that overlies the main reservoir. However, these inversion models suffer from non-uniqueness and uncertainty, and the inclusion of useful geological information is still limited. We develop a Bayesian inversion method that integrates the electrical resistivity distribution from MT surveys with borehole methylene blue data (MeB), an indicator of conductive clay content. MeB data is used to inform structural priors for the MT Bayesian inversion that focus on inferring with uncertainty the shallow conductor boundary in geothermal fields. By incorporating borehole information, our inversion reduces non-uniqueness and then explicitly represents the irreducible uncertainty as estimated depth intervals for the conductor boundary. We use Markov chain Monte Carlo (McMC) and a one-dimensional three-layer resistivity model to accelerate the Bayesian inversion of the MT signal beneath each station. Then, inferred conductor boundary distributions are interpolated to construct pseudo-2D/3D models of the uncertain conductor geometry. We compared our approach against a deterministic MT inversion software on synthetic and field examples and showed good performance in estimating the depth to the bottom of the conductor, a valuable target in geothermal reservoir exploration.

scholarly journals Evaluation of a Straight-Ray Forward Model for Bayesian Inversion of Crosshole Ground Penetrating Radar Data

Electronics ◽  
2019 ◽  
Vol 8 (6) ◽  
pp. 630 ◽  
Author(s):  
Hui Qin ◽  
Xiongyao Xie ◽  
Yu Tang
Keyword(s):  
Ground Penetrating Radar ◽  
Computational Cost ◽  
Measurement Data ◽  
Forward Model ◽  
Bayesian Inversion ◽  
Inversion Method ◽  
Model Parameters ◽  
Model Structure ◽  
Modeling Error ◽  
Ground Penetrating

Bayesian inversion of crosshole ground penetrating radar (GPR) data is capable of characterizing the subsurface dielectric properties and qualifying the associated uncertainties. Markov chain Monte Carlo (MCMC) simulations within the Bayesian inversion usually require thousands to millions of forward model evaluations for the parameters to hit their posterior distributions. Therefore, the CPU cost of the forward model is a key issue that influences the efficiency of the Bayesian inversion method. In this paper we implement a widely used straight-ray forward model within our Bayesian inversion framework. Based on a synthetic unit square relative permittivity model, we simulate the crosshole GPR first-arrival traveltime data using the finite-difference time-domain (FDTD) and straight-ray solver, respectively, and find that the straight-ray simulator runs 450 times faster than its FDTD counterpart, yet suffers from a modeling error that is more than 7 times larger. We also perform a series of numerical experiments to evaluate the performance of the straight-ray model within the Bayesian inversion framework. With modeling error disregarded, the inverted posterior models fit the measurement data nicely, yet converge to the wrong set of parameters at the expense of unreasonably large number of iterations. When the modeling error is accounted for, with a quarter of the computational burden, the main features of the true model can be identified from the posterior realizations although there still exist some unwanted artifacts. Finally, a smooth constraint on the model structure improves the inversion results considerably, to the extent that it enhances the inversion accuracy approximating to those of the FDTD model, and further reduces the CPU demand. Our results demonstrate that the use of the straight-ray forward model in the Bayesian inversion saves computational cost tremendously, and the modeling error correction together with the model structure constraint are the necessary amendments that ensure that the model parameters converge correctly.

scholarly journals Earthquake-Induced Landslide Risk Assessment: An Example from Sakhalin Island, Russia

Geosciences ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 305 ◽  
Author(s):  
Alexey Konovalov ◽  
Yuriy Gensiorovskiy ◽  
Valentina Lobkina ◽  
Alexandra Muzychenko ◽  
Yuliya Stepnova ◽  
...  
Keyword(s):  
Risk Assessment ◽  
Seismic Hazard ◽  
Ground Motion ◽  
Sakhalin Island ◽  
Landslide Risk ◽  
Hazard Map ◽  
Probabilistic Technique ◽  
Landslide Risk Assessment ◽  
Seismic Hazard Map ◽  
The Given

Damages caused by earthquake-induced ground effects can be of the order or significantly exceed the expected damages from ground shaking. A new probabilistic technique is considered in this study for earthquake-induced landslide risk assessment. A fully probabilistic technique suggests a multi-stage hazard assessment. These stages include the determination of seismic hazard curves and landslide probabilistic models, a vulnerability assessment, and geotechnical investigations. At each of the stages, the uncertainties should be carefully analyzed. A logic tree technique, which handles all available models and parameters, was used in the study. The method was applied considering child education facilities located at the foot of a natural slope in the south of Sakhalin Island which is known as an active seismic and land sliding area. The significant differences in the ground motion scenario in terms of the 475-year seismic hazard map and the fully probabilistic approach considered suggests that seismic landslide risk could be underestimated or overestimated when using the 475-year seismic hazard map for risk assessment. The given approach follows the rational risk management idea that handles well all possible ground motion scenarios, slope models, and parameters. The authors suggest that the given approach can improve geotechnical studies of slope stability.

The 1904 Ms6.8 Mw7.0-7.2 Cape Turnagain, New Zealand, earthquake

2006 ◽  
Vol 39 (4) ◽  
pp. 183-207
Author(s):  
G. L. Downes
Keyword(s):  
New Zealand ◽  
Surface Wave ◽  
Seismic Hazard ◽  
Goodness Of Fit ◽  
Central Business District ◽  
Maximum Magnitude ◽  
Surface Wave Magnitude ◽  
Plate Interface ◽  
Attenuation Relations ◽  
Instrumental Records

The 1904 August 09 NZT (August 08 UT) MS6.8 earthquake caused widespread structural and chimney damage from Napier to Wellington and was felt over a large part of New Zealand. Other than a brief paper in 1905, and determinations of its surface wave magnitude in the last 20 years, little has been done to better locate the earthquake or detail its effects. Comprehensive data have now been obtained from searches of historical documents, including newspapers, private and government papers, as well as instrumental records. Interpretation of the intensity data shows that the earthquake was probably centred near Cape Turnagain at relatively shallow depth. The paucity of aftershocks suggests that the earthquake occurred either on the subduction interface, or in the lower seismicity band or upper mantle of the subducting Pacific Plate. The area encompassed by the higher intensity isoseismals suggests the earthquake had a magnitude greater than the calculated surface wave magnitude MS6.75 ± 0.14 — possibly as high as MW7.2. At this magnitude, the earthquake becomes a more significant event in New Zealand’s historical record, and certainly the largest earthquake suspected of rupturing the plate interface along the Hikurangi Margin. A notable feature of the earthquake is the chimney and parapet damage caused in parts of Wellington Central Business District, approximately 170 km from the epicentre. Much of the city and inner suburbs experienced MM5-6, while MM6-7 occurred in several areas, mostly in those areas that are recognised as possibly susceptible to shaking enhancement, but also in several locations outside these areas. The 1904 Cape Turnagain earthquake has several implications for seismic hazard dependent on whether it was intra-slab or on the plate interface. Of particular importance, are the questions whether the damage in Wellington is exceptional and could represent microzone, focussing or directivity effects; the goodness of fit of the intensity distribution to modelled isoseismals using published attenuation relations; the compatibility of the magnitude with the maximum magnitude/magnitude cut-offs used in this area in the New Zealand Probabilistic Seismic Hazard model; and finally, the possibility that the 1904 earthquake might characterise plate interface earthquakes in southern Hawke’s Bay.

Sign in / Sign up

Export Citation Format

Share Document