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1.媒体来源:
外媒 phys.org
2.记者署名:
edited by Gaby Clark, reviewed by Robert Egan
3.完整新闻标题:
California's tectonic stress has reached record level, earthquake model
reveals
模型显示加州地壳应力已创历史新高!极限未知
4.完整新闻内文:
California's tectonic stress has reached record level, earthquake model
reveals
by University of Bern
edited by Gaby Clark, reviewed by Robert Egan
模型显示加州地壳应力已创历史新高!极限未知
伯恩大学 提供
由加比·克拉克 编辑 ，罗伯特·伊根审阅
https://i.urusai.cc/weVOK.jpg
Earthquakes usually occur along fracture zones in Earth's crust, where large
tectonic plates slide past one another and become locked. Stress builds up
over long periods and is suddenly released in the form of an earthquake. In
Southern California, the San Andreas and San Jacinto faults are among the
most significant of these zones, accommodating most of the plate motion in
the region.
Where the two fault systems approach each other northeast of Los Angeles lies
the Cajon Pass—a tectonically complex junction where a rupture on one fault
could potentially cross onto the other. Since the last major earthquake to
affect the wider Los Angeles region, the Fort Tejon earthquake of 1857, with
a magnitude of 7.9, tectonic stress along the fault segments has built up
continuously during a prolonged quiet period that has long concerned
researchers, given the potential for a large future rupture.
In a new study led by Dr. Liliane Burkhard of the Division of Space Research
and Planetary Sciences (WP) at the Physics Institute of the University of
Bern, an international research team modeled 1,000 years of earthquake
history along the southern San Andreas and San Jacinto fault systems to
estimate the present-day stress loading at Cajon Pass. Researchers from the
University of Hawai at Mānoa, the U.S. Geological Survey Earthquake
Science Center in Pasadena, and the Scripps Institution of Oceanography at UC
San Diego were involved.
地震通常发生在地球地壳的断层带，那里大型构造板块会相互滑动并相互锁定。应力在长
期累积后突然以地震的形式释放。在南加州，圣安德烈亚斯断层和圣哈辛托断层是其中最
重要的断层带，承载着该地区大部分的板块运动。
在洛杉矶东北部，两条断层系统交会处是卡洪山口—一个构造复杂的交会点，一条断层
的破裂有可能蔓延到另一条断层上。自1857年震级为7.9级的特洪堡地震（上一次影响大
洛杉矶地区的大地震）以来，断层段的构造应力在一段漫长的平静期中持续积累，鉴于未
来可能发生大规模破裂，这长期以来一直令研究人员担忧。
在伯尔尼大学物理研究所太空研究与行星科学部（WP）的莉莉安·伯克哈德博士领导的一
项新研究中，一个国际研究团队模拟了圣安德烈亚斯断层南部和圣哈辛托断层系统沿线
1000年的地震历史，以估算卡洪山口目前的应力负荷。参与这项研究的研究人员来自夏威
夷大学马诺阿分校、美国地质调查局帕萨迪纳地震科学中心、加州大学圣地牙哥分校史克
里普斯海洋研究所。
The results show that tectonic stresses in the region have reached and, in
some cases, exceeded the highest levels of the last millennium.
In the study, the researchers also introduced the concept of Cajon Pass as an
"earthquake gate," a junction that controls whether large earthquakes remain
confined to a single fault or propagate across both systems simultaneously.
The study has just been published in Journal of Geophysical Research: Solid
Earth.
结果表明，该地区的构造应力已经达标，并且在某些情况下超过了过去一千年来的最高水
平。
在这项研究中，研究人员也提出了卡洪山口作为“地震闸门”的概念，它控制着大地震是
局限于单一断层还是同时跨越两个断层系统传播。这项研究已发表在《地球物理研究期刊
：固体地球》。
Modeling 1,000 years of earthquake history
To investigate how stress along the San Andreas and San Jacinto faults and at
the critical Cajon Pass junction has evolved over time, the research team
constructed a physics-based, four-dimensional earthquake cycle model that
simulates processes in three spatial dimensions and over time. The
researchers then fed the model a 1,000-year earthquake record reconstructed
from geological evidence such as radiocarbon dating, tree-ring anomalies and
historical documentation of ground ruptures.
"The model tracks how each earthquake changes stress on neighboring fault
segments, how stress accumulates during the quiet intervals between events,
and how the deeper layers of the crust slowly relax following large
ruptures," Burkhard explains.
"This simulation allows us to understand how stresses in the fault system
build up over centuries," Burkhard continues. "By running the earthquake
history of Southern California as a simulation, we can estimate the extent to
which the fault system is already under stress today."
The researchers show that stresses in the region are currently at their
highest level in the last 1,000 years.
模拟1000年的地震历史
为了探讨圣安德烈亚斯断层和圣哈辛托断层以及关键的卡洪山口交汇处的应力如何随时间
演变，研究团队建立了一个基于物理学的四维地震周期模型，该模型能够模拟三维空间和
时间维度上的过程。随后，研究人员将根据放射性碳定年、树木年轮异常和历史地壳断裂
记录等地质证据重建的1000年地震记录输入到该模型中。
“该模型追踪每次地震如何改变相邻断层段的应力，应力如何在地震事件之间的平静期积
累，以及地壳深层在大破裂后如何缓慢松弛，”伯克哈德解释。
“这项模拟使我们能够了解断层系统中的应力是如何在几个世纪中累积起来的，”伯克哈
德继续说道。 “透过模拟南加州的地震历史，我们可以估算出断层系统目前承受的应力
程度。”
研究人员表示，该地区目前面临的压力处于近1000年来的最高水准。
'Earthquake gate' as a decisive key factor
A key finding of the study is that the Cajon Pass can act as a so-called
"earthquake gate," a junction that controls whether large ruptures remain
confined to a single fault or cross both fault systems. Historical examples
of both behaviors exist: The Fort Tejon earthquake of 1857 terminated at
Cajon Pass and did not involve the San Jacinto Fault, while the Wrightwood
earthquake of 1812 ruptured through the junction and across both systems in a
single through-going event.
"The earthquake gate concept captures something important about how fault
junctions work," Burkhard explains.
"Cajon Pass doesn't simply block or channel earthquakes: It responds to
stress conditions, and those conditions change over centuries."
“地震闸门”作为决定性关键因素
该研究的一项关键发现是，卡洪山口可以起到所谓的“地震闸门”作用，它控制着大型地
震破裂是局限于单一断层还是跨越两个断层系统。历史上存在这两种情况的例子：1857年
的特洪堡地震止于卡洪山口，并未涉及圣哈辛托断层；而1812年的赖特伍德地震则穿过该
交汇处，在一次贯穿性地震中跨越了两个断层系统。
“地震闸门的概念捕捉到了断层连接处运作方式的一些重要特征，”伯克哈德解释。
“卡洪山口并非简单地阻挡或引导地震：它会对应力条件做出反应，而这些条件会随着时
间的推移而变化。”
The study also shows that the decisive factor is not only how much stress has
built up on a single fault, but how aligned the stresses on the two fault
systems are. When the stress on both faults rises in concert over time,
toward similarly high levels, conditions favor a large joint rupture crossing
both systems. When stress levels evolve out of step with each other, ruptures
are more likely to terminate at the junction rather than propagate further.
Currently, modeled stress has reached 3.6 MPa on the San Jacinto-Bernardino
section, exceeding the highest value seen anywhere in the 1,000-year
simulation. On the neighboring Mojave South section of the San Andreas Fault,
it is 2.8 MPa. Both segments are therefore highly and relatively similarly
stressed, placing the system in a configuration that historically has
preceded joint ruptures.
"So not only is it concerning that the stresses are reaching historic highs,"
Burkhard says, "but also that the relative stress conditions between the two
fault systems are approaching the range we associate with major ruptures
crossing both faults simultaneously—and that is a scenario with much larger
consequences for the region."
研究还表明，决定性因素不仅在于单一断层上累积的应力大小，还在于两个断层系统上的
应力是否一致。当两个断层上的应力随时间同步上升至相似的高水准时，有利于形成横跨
两个断层的大型节理破裂。而当应力水准变化不一致时，破裂更有可能在交会处终止，而
不是进一步扩展。
目前，模拟应力在圣哈辛托-贝尔纳迪诺断层段已达到3.6兆帕，超过了1000年模拟中任何
位置的最高值。在邻近的圣安德烈亚斯断层莫哈韦南段，应力为2.8兆帕。因此，这两个
断层段都处于较高且相对接近的应力状态，使该系统处于历史上节理破裂发生的先兆状态
。
“因此，令人担忧的不仅是应力达到了历史最高水平，”伯克哈德说，“而且两个断层系
统之间的相对应力条件正接近我们所说的同时跨越两个断层的重大破裂的范围—这种情
况对该地区的影响要大得多。”
Increased risk in densely populated regions
A joint rupture of the San Andreas Fault and the San Jacinto Fault that
crosses the Cajon Pass would be a much more severe event than one limited to
a single fault. The affected region includes some of the most densely
populated, infrastructure-critical corridors in the U.S., including the
greater Los Angeles area, San Bernardino, Riverside and the Coachella Valley.
Major highways, railroads and energy infrastructure run through the Cajon
Pass itself.
"The question of when and how the next major earthquake will occur in this
region is one of the most pressing problems in applied geoscience. Our
results provide a clearer, physics-based picture of the current stress state
of the fault system, and the framework we developed is applicable not just to
California, but also to other complex fault junctions worldwide," Burkhard
says.
However, Burkhard emphasizes: "The study is not a prediction of when an
earthquake will occur. What we can say is that the system is critically
stressed and that physics-based models like ours give a clearer picture of
the range of scenarios we should be prepared for. This information is
important for hazard assessment, infrastructure planning, and emergency
preparedness."
人口稠密地区风险增加
圣安德烈亚斯断层和横跨卡洪山口的圣哈辛托断层同时断裂，其后果将远比单一断层断裂
严重得多。受影响区域包括美国人口最稠密、基础设施最为关键的走廊地带，例如大洛杉
矶地区、圣贝纳迪诺县、河滨县和科切拉谷。主要公路、铁路和能源基础设施均穿过卡洪
山口。
“下一次大地震何时以及如何发生在这个地区，是应用地球科学领域最紧迫的问题之一。
我们的研究结果从物理学的角度更清晰地展现了断层系统当前的应力状态，我们建立的框
架不仅适用于加利福尼亚州，也适用于世界各地其他复杂的断层交汇处，”伯克哈德说。
然而，伯克哈德强调：“这项研究并非预测地震何时发生。我们只能说，该系统正处于临
界压力之下，而像我们这样的基于物理的模型能够更清晰地展现我们应该做好准备应对的
各种情景。这些信息对于灾害评估、基础设施规划和应急准备至关重要。”
5.完整新闻连结 (或短网址)不可用YAHOO、LINE、MSN等转载媒体:
https://reurl.cc/V2Vgl6
6.备注:
不知道是南极还是加州的地图会先重画？
https://i.urusai.cc/qwWln.jpg