I thought my first copy was lost: I cannot find it in my office shelf. I scanned all my books back and forth, but to no avail. And then I remembered: I gave my copy to my sister years ago. That explains it.

I love Writing Tools. Strunk and White may give you the bare bones for writing well, but Roy Peter Clark gives you the tools to dissect a prose like a corpse, as what da Vinci did to study the anatomy of the human body. Knowing how a prose is designed allows you to think of writing as a design process: how to connect the parts and stitch them together. Well, there's always a danger of making a Frankenstein monster--something you see in this age of Google and Wikipedia: different sentences from diverse voices and tenses lumped together to form a hideous paragraph. The danger is there, but the reward is greater: ars poetica--the perfection of the word made flesh.

I went to FullyBooked, but there is no more copy left in all their branches. So I went to National Bookstore.

"Miss, do you have the book, Writing Tools, by Roy Peter Clark?" I asked

"Please write down the title and author," she said and gave me a piece of post-it paper. Then she typed something in her computer.

"Writing Tools: 50 Strategies for Every Writer? Is this the book?" She asked.

"Yes, that's the book," I said.

She went upstairs through a spiral staircase. After a while, she came down holding a book in spring green cover. It's Writing Tools.

I shall be a writer again. Tonight, I shall write the saddest lines.

## 24 November 2017

### Bought Roy Peter Clark's book, "Writing Tools"

Assistant Professor, Department of Physics, Ateneo de Manila University. Program Head, Upper Atmosphere Dynamics, Manila Observatory.

## 16 November 2017

### Strike, dip, and rake directions in focal mechanism

Vincent S. Cronin wrote A Primer on Focal Mechanism Solutions for Geologists (2010). My interest in his work is in his descriptions of fault vectors and angles. I need to use these standard names if I wish to write a paper on Focal Mechanism of Earthquakes.

Based on Cronin's diagram in p. 6, the reference strike, which we shall denote by $\mathbf e_{strike}$ appears to be the direction of the fault line as seen from a drone camera flying overhead high above the fault. The dip vector, which we shall denote by $\mathbf e_{dip}$, is a vector perpendicular to the reference strike $\mathbf e_{strike}$ and lies along the fault plane. The direction of $\mathbf e_{dip}$ is downward along the fault in Cronin. In this way, if we define the rake $\mathbf e_{rake}$ as the direction of the movement of the one side of the fault, then $\mathbf e_{rake}$ can be expressed as a rotation of $\mathbf e_{strike}$ about $\mathbf e_{dip}\times\mathbf e_{strike}$ by an angle $\theta_{rake}$, which is positive if the rotation is counterclockwise and negative if clockwise, following the right hand rule. These considerations results to the following expression for the rake direction $\mathbf e_{rake}$:

\begin{equation}

\mathbf e_{rake} = \mathbf e_{strike}\cos\theta_{rake} - \mathbf e_{dip}\sin\theta_{dip}.

\end{equation}

But even then, there is an uncertainty in the definition of the strike direction $\mathbf e_{strike},$ since $-\mathbf e_{strike}$ can also be the initial definition. Perhaps, the strike direction should be defined as that which makes an acute angle with respect to the north direction.

Based on Cronin's diagram in p. 6, the reference strike, which we shall denote by $\mathbf e_{strike}$ appears to be the direction of the fault line as seen from a drone camera flying overhead high above the fault. The dip vector, which we shall denote by $\mathbf e_{dip}$, is a vector perpendicular to the reference strike $\mathbf e_{strike}$ and lies along the fault plane. The direction of $\mathbf e_{dip}$ is downward along the fault in Cronin. In this way, if we define the rake $\mathbf e_{rake}$ as the direction of the movement of the one side of the fault, then $\mathbf e_{rake}$ can be expressed as a rotation of $\mathbf e_{strike}$ about $\mathbf e_{dip}\times\mathbf e_{strike}$ by an angle $\theta_{rake}$, which is positive if the rotation is counterclockwise and negative if clockwise, following the right hand rule. These considerations results to the following expression for the rake direction $\mathbf e_{rake}$:

\begin{equation}

\mathbf e_{rake} = \mathbf e_{strike}\cos\theta_{rake} - \mathbf e_{dip}\sin\theta_{dip}.

\end{equation}

But even then, there is an uncertainty in the definition of the strike direction $\mathbf e_{strike},$ since $-\mathbf e_{strike}$ can also be the initial definition. Perhaps, the strike direction should be defined as that which makes an acute angle with respect to the north direction.

## 15 November 2017

### Trend and plunge angles of faults

In his web page on Data in Structural Geology, W. F. Waldron of University of Alberta defined fault directions in terms of the trend angle $T$ and the plunge angle $P$. Here, we shall use his angular notations, but rewrite his coordinate system in vector form and redraw his diagram.

To define the direction of the trend-plunge unit vector $\mathbf e_{TP}$, we first define a right-handed coordinate system $\mathbf e_1$, $\mathbf e_2$, and $\mathbf e_3$ for East, North, and Up directions. The plunge angle $P$ would then be the angle made by $\mathbf e_{TP}$ with the East-North plane. In other words,

\begin{equation}

\mathbf e_{TP}\cdot\mathbf e_3 = -\cos(90^\circ-P)=-\sin P\equiv n,

\end{equation}

so that the projection onto the East-North Plane would then be $\cos P$. Next, we define the trend angle $T$ as the clockwise angle from North to East that the $\cos P$ projection of $\mathbf e{TP}$ makes with the Northward axis $\mathbf e_2$. This allows us to compute the other direction cosines along $\mathbf e_1$ and $\mathbf e_2$:

\begin{align}

\mathbf e_{TP}\cdot\mathbf e_1 &= \cos P\sin T\equiv \ell,\\

\mathbf e_{TP}\cdot\mathbf e_2 &= \cos P\cos T\equiv m.

\end{align}

Combining these relations, we obtain the expression for the vector $\mathbf e_{TP}$ in Eastward, Northward, and Upward coordinates:

\begin{align}

\mathbf e_{TP} &= \mathbf e_1\cos P\sin T + \mathbf e_2 \cos P\cos T -\mathbf e_3\sin P\nonumber\\

&=\ell\mathbf e_1 + m\mathbf e_2 + n\mathbf e_3.

\end{align}

To define the direction of the trend-plunge unit vector $\mathbf e_{TP}$, we first define a right-handed coordinate system $\mathbf e_1$, $\mathbf e_2$, and $\mathbf e_3$ for East, North, and Up directions. The plunge angle $P$ would then be the angle made by $\mathbf e_{TP}$ with the East-North plane. In other words,

\begin{equation}

\mathbf e_{TP}\cdot\mathbf e_3 = -\cos(90^\circ-P)=-\sin P\equiv n,

\end{equation}

so that the projection onto the East-North Plane would then be $\cos P$. Next, we define the trend angle $T$ as the clockwise angle from North to East that the $\cos P$ projection of $\mathbf e{TP}$ makes with the Northward axis $\mathbf e_2$. This allows us to compute the other direction cosines along $\mathbf e_1$ and $\mathbf e_2$:

\begin{align}

\mathbf e_{TP}\cdot\mathbf e_1 &= \cos P\sin T\equiv \ell,\\

\mathbf e_{TP}\cdot\mathbf e_2 &= \cos P\cos T\equiv m.

\end{align}

Combining these relations, we obtain the expression for the vector $\mathbf e_{TP}$ in Eastward, Northward, and Upward coordinates:

\begin{align}

\mathbf e_{TP} &= \mathbf e_1\cos P\sin T + \mathbf e_2 \cos P\cos T -\mathbf e_3\sin P\nonumber\\

&=\ell\mathbf e_1 + m\mathbf e_2 + n\mathbf e_3.

\end{align}

## 12 November 2017

### Writing three paragraphs per sitting is liberating

With three paragraphs I can already tell a story--a story with a beginning, middle, and end--though not necessarily in that order, as Jean-Luc Godard would say.

There is sheer joy in writing--something like chiseling a Pieta from a marble block with letters, words, and paragraphs. Then something takes shape: the words become the mirror of my mind. "In the beginning was the Word," says the John the Beloved. Christ is the Word of God. Christ is the image of God---perhaps in the same way as our words reveal who we are. And yet in this case our metaphor fail, though they are the closest theologians can think of in describing the relationship of the Father and the Son in the Uni Trinoque or the Holy Trinity.

I haven't blogged for a long, long time. And writing these three paragraph spurts has been cathartic. I just need to get words out of my heart, before I go crazy trying to hold them in. And so with Jeremiah, I pray: "You duped me, O LORD, and I let myself be duped...I say to myself, I will not mention him, I will speak in his name no more. But then it becomes like fire burning in my heart, imprisoned in my bones; I grow weary holding it in, I cannot endure it." (Jer 20:7-9)

There is sheer joy in writing--something like chiseling a Pieta from a marble block with letters, words, and paragraphs. Then something takes shape: the words become the mirror of my mind. "In the beginning was the Word," says the John the Beloved. Christ is the Word of God. Christ is the image of God---perhaps in the same way as our words reveal who we are. And yet in this case our metaphor fail, though they are the closest theologians can think of in describing the relationship of the Father and the Son in the Uni Trinoque or the Holy Trinity.

I haven't blogged for a long, long time. And writing these three paragraph spurts has been cathartic. I just need to get words out of my heart, before I go crazy trying to hold them in. And so with Jeremiah, I pray: "You duped me, O LORD, and I let myself be duped...I say to myself, I will not mention him, I will speak in his name no more. But then it becomes like fire burning in my heart, imprisoned in my bones; I grow weary holding it in, I cannot endure it." (Jer 20:7-9)

### If you have time, read Ecclesiastes 12:1-8

It is a meditation on old age. But what really captivates me is the power of its poetry. It is just one long sentence separated by semicolons, and then one short sentence with

Or perhaps instead of a poster, I shall write a story.

*vanity*repeated thrice:Remember your Creator in the days of your youth, before the evil days come and the years approach of which you will say, “I have no pleasure in them”; 2 before the sun is darkened and the light and the moon and the stars and the clouds return after the rain; 3 * when the guardians of the house tremble, and the strong men are bent; when the women who grind are idle because they are few, and those who look through the windows grow blind; 4 When the doors to the street are shut, and the sound of the mill is low; when one rises at the call of a bird, and all the daughters of song are quiet; 5 when one is afraid of heights, and perils in the street; when the almond tree blooms, and the locust grows sluggish and the caper berry is without effect, because mortals go to their lasting home, and mourners go about the streets; 6 * before the silver cord is snapped and the golden bowl is broken, and the pitcher is shattered at the spring, and the pulley is broken at the well, 7 and the dust returns to the earth as it once was, and the life breath returns to God who gave it.* a 8 Vanity of vanities, says Qoheleth, all things are vanity! (Eccl 12:1-8)Someday, perhaps next year, I wish to make a poster illustrating the nouns and verbs described in this passage: the darkening sun, the tranquil night, the old warrior, the idle grindstone, the blossoming almond tree, the tired locust, the caper berry, the street mourners, the snapped silver cord, the broken golden bowl, the shattered pitcher, the broken pulley.

Or perhaps instead of a poster, I shall write a story.

## 11 November 2017

### Today, I deleted all my blog posts

Well, not exactly. I only hid them from view. They are still there in in my blog, buried like a treasure in the field. Perhaps, this is what Virgil felt regarding his Iliad. Or Brahms regarding his musical compositions. Or Gerard Manley Hopkins regarding his poems. Nothing short of perfection should be regarded as art. Carthage must be destroyed.

I need a new leaf in life. I felt stretched and weary, spread out too thinly butter, as Bilbo would say. I felt that my previous posts had defined me as just one of those bloggers for hire, churning out dozens of utilitarian how-to posts and listicles every week to feed the insatiable appetite of social media platforms and search engines. I am tired running after eyeballs. I need the solitude of deep writing. I need a monastery.

I am Jaguar Paw! This is my forest! I am Quirino Sugon Jr. This is my blog.

I need a new leaf in life. I felt stretched and weary, spread out too thinly butter, as Bilbo would say. I felt that my previous posts had defined me as just one of those bloggers for hire, churning out dozens of utilitarian how-to posts and listicles every week to feed the insatiable appetite of social media platforms and search engines. I am tired running after eyeballs. I need the solitude of deep writing. I need a monastery.

I am Jaguar Paw! This is my forest! I am Quirino Sugon Jr. This is my blog.

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