Seismic Design Criteria, Ground Motion, and Community ...

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Seismic Design Criteria, Ground Motion, and Community Seismic

Resilience - California Experiences Liping Yan （颜利平）, Ph.D., P.E., G.E.

Technical Specialist Los Angeles Department of Water and Power

(Email: [email protected])

Session B - Technology Exchange

27th Modern Engineering Technology Seminar 2018 October 22-24, 2018

Taipei, Taiwan

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OUTLINE • INTRODUCTION • GEOLOGIC BACKGROUND • SCIENTIFIC MODELS • UCERF3: A NEW EARTHQUAKE FORECAST

FOR CALIFORNIA’S COMPLEX FAULT SYSTEM

• SEISMIC DESIGN CRITERIA • GROUND MOTION • COMMUNITY SEISMIC RESILIENCE • RECOMMENDATIONS – WHAT TAIWAN CAN

LEARN FROM CALIFORNIA EXPERIENCES

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1. INTRODUCTION

• The beautiful

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1. INTRODUCTION

• The beautiful

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1. INTRODUCTION

• The beautiful

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1. INTRODUCTION

• The beautiful

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1. INTRODUCTION

• The ugly

The Loma Prieta Earthquake: October 17, 1989 at 5:04 p.m., M6.9

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1. INTRODUCTION

The Loma Prieta Earthquake: October 17, 1989 at 5:04 p.m., M6.9

• The ugly

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1. INTRODUCTION • The ugly

The Northridge Earthquake: January 17 at 4:30:55 a.m., M6.7

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1. INTRODUCTION

• The ugly

The Northridge Earthquake: January 17 at 4:30:55 a.m., M6.7

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1. INTRODUCTION

• The ugly

The Hualien Earthquake: February 6 at 11:50 p.m., M6.4

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2. GEOLOGIC BACKGROUND Pacific Ring of Fire: • It is a major area in the basin of the Pacific Ocean where many earthquakes and volcanic eruptions occur. In a 40,000 km horseshoe shape, it is associated with a nearly continuous series of oceanic trenches, volcanic arcs, and volcanic belts and plate movements.

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2. GEOLOGIC BACKGROUND Pacific Ring of Fire: • It has 452 volcanoes (more than 75% of the world's active and dormant volcanoes). • The Ring of Fire is sometimes called the circum-Pacific belt.

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2. GEOLOGIC BACKGROUND Pacific Ring of Fire: • About 90% of the world's earthquakes and 81% of the world's largest earthquakes occur along the Ring of Fire. • All but three of the world's 25 largest volcanic eruptions of the last 11,700 years occurred at volcanoes in the Ring of Fire.

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2. GEOLOGIC BACKGROUND Pacific Ring of Fire: • The Ring of Fire is a direct result of plate tectonics: the movement and collisions of lithospheric plates, especially subduction in the northern portion. • California and Taiwan are both on the Ring of Fire.

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Geologic Features of California Main Geologic Features

• It is sandwiched between the Pacific and North American tectonic plates

• The former migrates northwest about two inches per year compared to the latter.

• It is full of faults.

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3. SCIENTIFIC MODELS

• Earthquake Rupture Forecast It tells us where and when the Earth might slip along the State’s many faults.

• Ground Motion Prediction

It estimates the subsequent shaking given one of the fault ruptures.

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4. UCERF3: A NEW EARTHQUAKE FORECAST FOR CALIFORNIA’S COMPLEX FAULT SYSTEM (Released by USGS on 3/10/2015)

• The new model, referred to as the third Uniform California Earthquake Rupture Forecast, or “UCERF3” (http://www.WGCEP.org/UCERF3), provides authoritative estimates of the magnitude, location, and likelihood of earthquake fault rupture throughout the State.

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What Are New?

There are more than 350 fault sections in the model. It considers more than 250,000 different

fault-based earthquakes, including multifault ruptures. It also includes the notion of fault

“readiness,” where earthquake likelihoods go down on faults that have recently ruptured, and build back up with time as tectonic stresses reaccumulate.

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New Findings of UCERF3

Overall the results confirm previous findings, but with some significant change because of model improvements. For example, compared to the previous forecast (UCERF2), the likelihood of moderate-sized earthquakes (magnitude 6.5 to 7.5) is lower, whereas that of larger events is higher.

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Earthquake Occurring Rate: • Considering the entire region, the average time between magnitude 6.7 and larger earthquakes is 1 about every 6.3 years. • For magnitude 8 and larger, the rate has an expected repeat time of 494 years. • For 5 and greater earthquakes, the rate is 8.3 per year.

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Likelihood of Experiencing One or More Earthquakes in the Next 30 Years: a) The likelihood for magnitude 6.7 and larger earthquakes somewhere in the entire region remains near certainty (greater than 99 percent). b) The chance of a Northridge size quake is slightly higher in Northern California than Southern California — 95 percent versus 93 percent.

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Likelihood of Experiencing One or More Earthquakes in the Next 30 Years: c) There is a 93 percent chance of a magnitude 7 or larger occurring and a 48 percent chance of magnitude 7.5. d) The likelihood is 7 percent for magnitude 8 and greater. e) There is a 19 percent chance that a Northridge size quake will unzip the southern section compared to a 6.4 percent chance for the northern section.

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Why Is There a “Big One”?

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The Hazard or Risk Implications:

Depend on many factors.

e.g.:

The risk to tall buildings or large bridges may increase, but the risk to residential homes may be lower.

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• 2014 update of the U.S. Geological Survey National Seismic Hazard Maps

• Building codes

• CEA to evaluate insurance premiums

• Risk mitigation

• Ultimate goal of increasing public safety and community resilience

Uses of UCERF3:

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5. SEISMIC DESIGN CRITERIA

• Principles In the earthquake-resistant design, the structure is designed to be able to withstand the minor earthquakes and to resist the moderate earthquakes called design earthquakes (DE) without significant structural damages. A major earthquake called maximum considered earthquake (MCE) would not cause collapse of the properly designed and constructed structure and losses would be limited.

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• Major Considerations Soil Condition Structure Type or Building Usage Geographic Location

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• For Buildings International Building Code (IBC) - 2015 The code provisions are intended to protect public health and safety while avoiding both unnecessary costs and preferential treatment of specific materials or methods of construction.

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5. SEISMIC DESIGN CRITERIA • For Buildings

California Building Code (CBC) - 2016 The California Building Standards Code is the building code for California, and Title 24 of the California Code of Regulations (CCR). It is maintained by the California Building Standards Commission which is granted the authority to oversee processes related to the California building codes by California Building Standards Law.

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• For Buildings California Building Code (CBC) - 2016 The California building codes under Title 24 are established based on several criteria: standards adopted by states based on national model codes, national model codes adapted to meet California conditions, and standards passed by the California legislature that address concerns specific to California.

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5. SEISMIC DESIGN CRITERIA • For Buildings California Building Code (CBC) - 2016 To better account for many of the uncertainties associated with predicting earthquake occurrence, a probabilistic approach was used to estimate the ground motion hazard at the site. The current building code (CBC, 2016) requires all structures be designed to resist the earthquake effects of two-thirds of the corresponding Risk-Targeted Maximum Considered Earthquake (MCER) effects.

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5. SEISMIC DESIGN CRITERIA • For Buildings

California Building Code (CBC) - 2016 MCER is based on a uniform collapse risk objective of 1% probability of collapse in 50 years. The MCER ground motions are calculated assuming a generic building collapse fragility that has 10% collapse probability for the given MCER ground motions.

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5. SEISMIC DESIGN CRITERIA • For Buildings California Building Code (CBC) - 2016 Based on the location of the site and the site classification, the code-based design spectral acceleration parameters are developed using the current USGS Seismic Design Maps per the procedures of ASCE/SEI 7-10.

USGS On-line Tool: http://earthquake.usgs.gov/designmaps/us/application.php

http://earthquake.usgs.gov/designmaps/us/application.php

http://earthquake.usgs.gov/designmaps/us/application.php

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• For Buildings Example – Using CBC-2016

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• For Buildings Example – Using CBC-2016

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5. SEISMIC DESIGN CRITERIA • For Bridges

California Department of Transportation (Caltrans) Seismic Design Criteria (Version 1.7, April 2013)

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Caltrans Seismic Design Criteria (SDC)

Ground Motion Representation: For structural applications, seismic demand is represented using an elastic 5% damped response spectrum. In general, the Design Spectrum (DS) is defined as the greater of:

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• For Bridges

Caltrans SDC

Ground Motion Representation:

(1) A probabilistic spectrum based on a 5% in 50 years probability of exceedance (or 975-year return period); (2) A deterministic spectrum based on the largest median response resulting from the maximum rupture (corresponding to MMax) of any fault in the vicinity of the bridge site; (3) A statewide minimum spectrum defined as the median spectrum generated by a Magnitude 6.5 earthquake on a strike-slip fault located 12 kilometers from the bridge site

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Caltrans SDC

Ground Motion Representation: Using Caltrans On-line Tool:

http://dap3.dot.ca.gov/ARS_Online/index.php

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• For Bridges

Caltrans SDC

Example:

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• For Bridges

Caltrans SDC

Example:

Design Spectrum (5% Damping)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

Period (sec)

Spec

tral A

ccel

erat

ion

(g)

VS30 = 370 m/sVS30 = 290 m/sEnvelope

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5. SEISMIC DESIGN CRITERIA • For Reservoir Dams

California Department of Water Resources (DWR), Division of Safety of Dams (DSOD)

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DSOD Guidelines The seismic design criteria for the dam are based on Deterministic Seismic Hazard Analyses (DSHA). Peak ground acceleration (PGA) and spectral acceleration (SA) values at the 50th or 84th percentile are calculated for scenario earthquakes on active and conditionally active faults in the vicinity of the project site.

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DSOD Guidelines The percentile level for each scenario earthquake considered is based on the DSOD consequence-hazard matrix. The scenario earthquake resulting in the highest seismic demand is then selected as the Maximum Considered Earthquake (MCE).

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5. SEISMIC DESIGN CRITERIA • For Reservoir Dams - DSOD Guidelines

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5. SEISMIC DESIGN CRITERIA • For Reservoir Dams - DSOD Guidelines Example:

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5. SEISMIC DESIGN CRITERIA • For High Speed Rail Structures

California High-Speed Rail Authority (CHSRA) Design Criteria

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CHSRA Design Criteria The goal of these criteria is to safeguard against loss of life and major failures due to Maximum Considered Earthquake (MCE), and interruption of High-Speed Train (HST) operations due to structural or track damage and derailment caused by Operating Basis Earthquake (OBE).

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CHSRA Design Criteria Two levels of seismic performance criteria are

defined:

• No Collapse Performance Level (NCL) – For Maximum Considered Earthquake (MCE) design.

• Operability Performance Level (OPL) – For Operating Basis Earthquake (OBE) design.

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CHSRA Design Criteria

For design, two design earthquakes, the Maximum Considered Earthquake (MCE) and the Operating Basis Earthquake (OBE), are defined:

• Maximum Considered Earthquake – Ground motions corresponding to greater of (1) a probabilistic spectrum based upon a 10% probability of exceedance in 100 years (i.e., a return period of 950 years); and (2) a deterministic spectrum based upon the largest median response resulting from the maximum rupture (corresponding to Mmax) of any fault in the vicinity of the structure.

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CHSRA Design Criteria • Operating Basis Earthquake – Ground motions

corresponding to a probabilistic spectrum based upon an 86% probability of exceedance in 100 years (i.e., a return period of 50 years).

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6. GROUND MOTION • Horizontal Peak Ground Acceleration

(PGA) and Spectral Accelerations (SA)

PGA and SA values are estimated using the 2014 Next Generation Attenuation (NGA) period specific Ground Motion Prediction Equations (GMPEs), which are empirically based on ground motion recordings from the Pacific Earthquake Engineering Research Center (PEER) NGA-West2 database.

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6. GROUND MOTION • Horizontal Peak Ground Acceleration

(PGA) and Spectral Accelerations (SA)

There are five NGA models which were developed by Abrahamson et al. (2013), Boore et al. (2013), Campbell and Bozorgnia (2013), Chiou and Youngs (2013), and Idriss (2013). PGA and SA values calculated from these five NGA models are usually weighted equally.

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7. COMMUNITY SEISMIC RESILIENCE • Significance

Occurrence of earthquakes is unavoidable. However we can reduce the seismic hazards and thread to life, property, and our economy by strengthening our community resilience. Resilience has become a hot topic in earthquake risk reduction policy.

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7. COMMUNITY SEISMIC RESILIENCE • Definition

Resilience is “the ability of a system, community or society exposed to hazards to resist, absorb, accommodate to, and recover from the effects of a hazard in a timely and efficient manner, including through the preservation and restoration of its essential basic structures and functions.” (UNISDR, 2009)

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7. COMMUNITY SEISMIC RESILIENCE • Community Resilience

An attribute of the community, a process, an outcome Increasing the ability of communities to adapt after a disaster is accepted as an important need by disaster experts and institutes around the globe

(UNISDR, Chengdu Declaration for Action, 2011; Djalante & Thomalla, 2011)

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7. COMMUNITY SEISMIC RESILIENCE • Disaster Management Cycle

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• Characteristics of Resilience http://www.resilientus.org/recognizing-resilient-communities/ Plodinec,J

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• Characteristics of a Resilient Community

1. Knowledgeable and healthy. It has the ability to assess, manage and monitor its risks. It can learn new skills and build on past experiences. 2. Organized. It has the capacity to identify problems, establish priorities and act. 3. Connected. It has relationships with external actors who provide a wider supportive environment, and supply goods and services when needed.

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• Characteristics of a Resilient Community

4. Infrastructure and services. It has strong housing, transport, power, water and sanitation systems. It has the ability to maintain, repair and renovate them. 5. Economic opportunities. It has a diverse range of employment opportunities, income and financial services. 6. Manage its natural assets. It recognizes their value and has the ability to protect, enhance and maintain them.

(ARUP International Development , September 2011)

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• Scenario Earthquake for Southern California - ShakeOut Earthquake Scenario

Purpose: Advance planning so that California will be ready when the inevitable “big one” and others recur.

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SOUTHERN CALIFORNIA AREA

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Goal: The goal in the ShakeOut Scenario is to identify the physical, social and economic consequences of a major earthquake in southern California , and in so doing, enable end users to identify what they can change now—before the earthquake—to avoid catastrophic impact after the inevitable earthquake occurs.

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GROUND SHAKING: 60%G SECONDS AFTER FAULT RUPTURE

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The magnitude 7.8 SCENARIO earthquake will cause about 1800 deaths and $213 billion of economic losses. These numbers are as low as they are because of aggressive retrofitting programs since 1994 that have increased the seismic resistance of buildings, highways and lifelines, and added economic resilience.

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The estimates of about 1800 deaths and $213 billion of economic losses are as large as they are because much more retrofitting could still be done.

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• Scenario Earthquake for Northern California - HayWired Earthquake Scenario

Goal: To simulate what the aftermath of a 7.0-magnitude earthquake along the Bay Area's Hayward Fault could look like.

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• HayWired Earthquake Scenario

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• Scenario Earthquake for Northern California - HayWired Earthquake Scenario

The estimates about 800 deaths and $100 billion of economic losses would be possible. It could strand around 20,000 people in elevators across northern California.

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• Actions Taken by City of Los Angeles

Resilience by Design Program Resilience by Design (a report released in December 2014) presents the recommendations of the Mayoral Seismic Safety Task Force. These recommendations address the city’s greatest vulnerabilities from earthquakes with significant and attainable solutions to:

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Protect the lives of our residents Improve the capacity of the City to respond to

earthquakes Prepare the City to recover quickly from

earthquakes Protect the economy of the City and all of

Southern California.

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• Actions Taken by City of Los Angeles The Mayoral Seismic Task Force evaluated

four areas of seismic vulnerability, namely:

Pre-1980 “non-ductile reinforced concrete” buildings

Pre-1980 “soft-first-story ” buildings Water system infrastructure (including impact

on firefighting capability) Telecommunications infrastructure

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Strengthen Our Buildings

Assess And Retrofit Pre-1980 Soft Story And Concrete Buildings

Soft Story Concrete Implement a Seismic Safety Rating System Create a Back To Business Program Mandatory Retrofit of Buildings that are

Excessively Damaged in Earthquakes

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洛杉矶市薄弱层建筑强制加固法规

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洛杉矶市脆性混凝土建筑强制加固法规

25 years

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Fortify Our Water System

Develop an Alternative Water System For Firefighting

Fortify the Los Angeles Aqueduct Fortify Other Aqueducts Fortify Water Storage Increase Local Water Sources Create a Seismic Resilient Pipe Network Implement a Resilience by Design Program at

DWP Develop a Statewide Seismic Resilience Bond

Measure

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• Actions Taken by City of Los Angeles Enhance Reliable Telecommunications

Maintain Internet Access After Earthquakes Protect the Power System at Fault Crossings Create a Citywide Backup Internet System Fortify Cellular Towers Advancement of Earthquake Early Warning

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What LADWP Are Doing Program development is being accomplished

through a management team effort investigating three requisites:

(1) defining characteristics of a seismically resilient Los Angeles Water System,

(2) identifying the current status of Water System seismic resilience, and

(3) recognizing aspects which may improve Water System seismic resilience.

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What LADWP Are Doing To proceed with the Program six initial

recommendations are identified as follows: (1) Establish an LADWP-wide Resilience Task

Force to oversee and provide resources to lead, support and ensure accomplishment of the Program.

(2) Prepare a plan for implementing the Program. (3) Implement Water System seismic planning,

evaluation, and monitoring to identify needed mitigations throughout the City and along the Los Angeles Aqueducts (LAA).

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What LADWP Are Doing To proceed with the Program six initial

recommendations are identified as follows: (4) Develop a seismically resilient pipe network. (5) Increase water supply and storage reliability, including o Identify mitigation alternatives for LAA crossing the San

Andreas Fault. o Enhance the Dam Safety Program using risk-based

methods. o Identify alternative water supply sources for firefighting. o Develop local supply sources to reduce dependence on

imported water and enhance water availability in emergencies.

(6) Enhance emergency response capabilities.

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What LADWP Are Doing

Examples:

(1) Installation of Seismically-Resistant Water Pipes. (2) Retrofit of Elizabeth Water Tunnel That Crosses San

Andres Fault

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8. RECOMMENDATIONS – WHAT TAIWAN CAN LEARN FROM CALIFORNIA EXPERIENCES

• Earthquakes can not be predicted. But earthquake forecast for mid- and long-term planning and preparedness is useful. Development or update of Uniform Taiwan Earthquake Rupture Forecast, similar to UCERF3, is recommended.

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• Development or enhancement of systematic Seismic Design Criteria for all essential structures in Taiwan is recommended.

• New earthquake data have been obtained. Establishment of comprehensive database for All Earthquake Records in Taiwan is recommended.

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• Updating Next Generation Attenuation Period Specific Ground Motion Prediction Equations That can be used for different areas in Taiwan is recommended.

• Development of various earthquake scenarios based on Taiwan’s geologic features is recommended.

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• New earthquake data have been obtained. Establishment of comprehensive database for All Earthquake Records in Taiwan is recommended.

• Initiative for Resilience by Design Program in Taiwan is proposed.

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Let Us Collaborate and Learn from Each Other !

May Taiwan and California Become More Seismically

Resilient !

Thank you !

Seismic Design Criteria, Ground Motion, and Community ...

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